JP7351692B2 - Steering control device - Google Patents

Description

The present invention relates to a steering control device.

2. Description of the Related Art Conventionally, an electric power steering system (EPS) including an actuator using a motor as a drive source is known as a vehicle steering system. Some of these EPSs acquire the steering angle of the steering wheel as an absolute angle including a range exceeding 360 degrees, and perform various controls based on the steering angle. As an example of such control, for example, Patent Documents 1 and 2 disclose a system that executes end contact mitigation control for alleviating the impact of so-called end contact, in which the rack end, which is the end of the rack shaft, hits the rack housing. ing. In the EPS of Patent Document 1, the impact on the end contact is alleviated by correcting the current command value corresponding to the target value of the motor torque output by the motor by a steering reaction force component based on the steering angle. Further, in the EPS of Patent Document 2, the impact of end contact is alleviated by limiting the current command value corresponding to the target value of motor torque output by the motor to be equal to or less than a limit value based on the steering angle.

Japanese Patent Application Publication No. 2015-20506 Patent No. 5962881

By the way, in the above-mentioned conventional configurations that perform end contact relaxation control, the rack end position where the movement of the rack shaft is regulated by the end contact is associated with the steering angle, and the same angle is the end position corresponding angle. is remembered as.

However, depending on the specifications of the vehicle, the end position corresponding angle may disappear, for example, when the ignition is turned off or when the vehicle-mounted battery is replaced. When the end position corresponding angle disappears in this way, it becomes impossible to execute end hit relaxation control, for example. Therefore, it is necessary to learn the end position corresponding angle, and at this time, it is required to accurately correspond the end position corresponding angle to the actual end angle at which end contact actually occurs.

An object of the present invention is to provide a steering control device that can learn an end position corresponding angle that accurately corresponds to an actual end angle.

A steering control device that solves the above problem includes a housing, a steered shaft housed in the housing so as to be able to reciprocate, and an actuator that uses a motor as a drive source to apply a motor torque that causes the steered shaft to reciprocate. An absolute steering angle, which is a rotation angle of a rotating shaft that is controlled by a steering device, and is convertible into a steering angle of a steered wheel connected to the steered shaft, and is expressed as an absolute angle that includes a range exceeding 360°. an absolute steering angle detection unit that detects an absolute steering angle, a restriction determination unit that determines whether movement of the steered shaft to the left or right is restricted, and a restriction determination unit that determines that movement of the steered shaft is restricted. A plurality of restriction position determination angles are obtained according to the absolute steering angle when the steering angle is adjusted, and based on the variance of the plurality of restriction position determination angles on the left side or the right side, the plurality of restriction position determination angles on the left side or the right side are determined as described above. a dispersion determination unit that determines whether the data is when the movement of the steered shaft is regulated due to the contact of the steered shaft with the housing; and an end abutment where the steered shaft abuts on the housing. An angle indicating that the steered shaft is at a left or right end position based on the plurality of restriction position determination angles determined to be data when movement of the steered shaft is restricted, and an end position corresponding angle setting section that sets an end position corresponding angle corresponding to the absolute steering angle.

For example, when the movement of the steered shaft is restricted by hitting a curb, etc., the position of the steered shaft changes depending on the situation when the steered wheels hit the curb, so the magnitude of the restriction position determination angle is likely to vary. On the other hand, when the movement of the steered shaft is regulated by the end abutment where the steered shaft comes into contact with the housing, the position of the steered shaft is determined depending on the structure of the steering device, so the size of the regulation position determination angle is less likely to vary. . Therefore, if the variance of the plurality of restriction position determination angles is large, it is considered that the movement of the steered shaft is restricted by hitting a curb or the like. On the other hand, if the variance of the plurality of restriction position determination angles is small, it is considered that the movement of the steered shaft is restricted by the end abutment. Therefore, by using the distribution of a plurality of restriction position determination angles as in the above configuration, it is possible to set an end position corresponding angle that accurately corresponds to the actual end angle.

In the above-mentioned steering control device, the dispersion determination unit is configured to determine a dispersion determination unit that is a dispersion value of each of n (where n is an integer of 2 or more) left or right regulation position determination angles θi (where i is a natural number). The value Vd is given by the following formula,

(However, θave is the average value of n restriction position determination angles θi), and is calculated using the average value of n restriction position determination angles θi, and determines each of the left and right side restriction positions when the movement of the steered shaft is restricted by the end contact. A predetermined variance value Vm is a value preset as a corner variance value, and a variance ratio Rd obtained by dividing the judgment variance value Vd by the predetermined variance value Vm is equal to or less than a variance threshold Rthn set according to n. In this case, it is preferable to determine that the n restriction position determination angles are data acquired when movement of the steered shaft is restricted by the end contact.

According to the above configuration, it is possible to suitably determine whether the n restriction position determination angles are data acquired when the movement of the steered shaft is restricted by end contact.
In the above-mentioned steering control device, the end position corresponding angle setting section sets the end position corresponding angle when the movement of the steered shaft is regulated by the end abutment where the steered shaft abuts on the housing. When the left and right restriction position determination angles that are determined to be data are acquired, it is the sum of the absolute value of the left restriction position determination angle and the absolute value of the right restriction position determination angle. A comparison is made between the stroke width and a stroke threshold corresponding to the entire stroke range of the steered shaft, and if the stroke width is larger than the stroke threshold, the stroke width is compared based on the left and right regulation position determination angles. , respectively set the end position corresponding angles on the left side and the right side, and when setting the end position corresponding angles, when the movement of the steered shaft is restricted by the end abutment where the steered shaft abuts the housing. If a plurality of the restriction position determination angles of only the left side or the right side are determined to be data , the left side determined to be the data when the movement of the steered shaft is restricted by the end contact. Alternatively, it is preferable to set the end position corresponding angle on the left side or the right side based on a plurality of restriction position determination angles on the right side.

According to the above configuration, when the restriction position determination angles on both the left and right sides can be obtained, it is possible to wait until a plurality of left or right restriction position determination angles are obtained by comparing the stroke width and the stroke threshold value. Therefore, it is possible to quickly set the end position corresponding angles on both the left and right sides that accurately correspond to the actual end angles. In addition, if multiple restriction position determination angles for only the left or right side are obtained, multiple left or right side determination angles that are determined to be data when the movement of the steering axis was restricted by end contact based on the variance are Since the end position corresponding angle on the left side or the right side is set based on the regulation position determination angle, it is possible to set the end position corresponding angle that accurately corresponds to the actual end angle.

In the above-mentioned steering control device, the regulation determination unit determines whether one of the left and right of the steered shaft is based on the angular velocity of the motor, the amount of change in angular velocity that is the amount of change in the angular velocity, and the steering torque input to the steering device. It is preferable to determine whether movement to is regulated.

According to the above configuration, it is possible to easily determine whether or not the movement of the steered shaft is restricted, for example, without providing a dedicated sensor for detecting movement of the steered shaft.
In the above steering control device, the end position corresponding angle setting unit is configured to set the plurality of restriction position determination angles on the left side or right side that are determined to be data when the movement of the steered shaft is restricted by the end stop. It is preferable to set an average value as the angle corresponding to the left or right end position.

According to the above configuration, it is possible to suitably set the end position corresponding angle that accurately corresponds to the actual end angle.
In the above steering control device, the end position corresponding angle setting unit is configured to set the plurality of restriction position determination angles on the left side or right side that are determined to be data when the movement of the steered shaft is restricted by the end stop. It is preferable to set the regulation position determination angle having the largest absolute value as the end position corresponding angle on the left side or the right side.

According to the above configuration, it is possible to suitably set the end position corresponding angle that accurately corresponds to the actual end angle.

According to the present invention, it is possible to learn an end position corresponding angle that accurately corresponds to an actual end angle.

FIG. 1 is a schematic configuration diagram of an electric power steering device according to a first embodiment. FIG. 1 is a block diagram of a steering control device according to a first embodiment. FIG. 3 is a block diagram of a limit value setting unit according to the first embodiment. FIG. 3 is a block diagram of an end position corresponding angle management unit according to the first embodiment. 5 is a flowchart illustrating a processing procedure for static regulation determination by a first regulation determination unit according to the first embodiment. 5 is a flowchart showing a processing procedure for dynamic restriction determination by a first restriction determination unit according to the first embodiment. FIG. 3 is a schematic diagram showing the relationship between absolute steering angle and pinion shaft torque in the first embodiment. 7 is a flowchart showing a processing procedure of end hit determination by the dispersion determination unit of the first embodiment. 5 is a flowchart showing a processing procedure for end hit determination by the update permission unit of the first embodiment. 7 is a flowchart showing a procedure for setting left and right end position corresponding angles by the end position corresponding angle setting unit of the first embodiment. 10 is a flowchart showing a processing procedure for end hit determination by an update permission unit according to the second embodiment.

(First embodiment)
A first embodiment of the steering control device will be described below with reference to the drawings.
As shown in FIG. 1, an electric power steering device (EPS) 2 as a steering device to be controlled by a steering control device 1 is a steering mechanism that steers steerable wheels 4 based on the operation of a steering wheel 3 by a driver. It is equipped with 5. Further, the EPS 2 includes an EPS actuator 6 as an actuator that provides the steering mechanism 5 with an assist force for assisting the steering operation.

The steering mechanism 5 includes a steering shaft 11 to which the steering wheel 3 is fixed, a rack shaft 12 as a steering shaft connected to the steering shaft 11, and a rack housing as a housing into which the rack shaft 12 is inserted so as to be reciprocally movable. 13, and a rack and pinion mechanism 14 that converts the rotation of the steering shaft 11 to the rack shaft 12. The steering shaft 11 is constructed by connecting a column shaft 15, an intermediate shaft 16, and a pinion shaft 17 in order from the side where the steering wheel 3 is located.

The rack shaft 12 and the pinion shaft 17 are arranged within the rack housing 13 at a predetermined intersection angle. The rack and pinion mechanism 14 is constructed by meshing rack teeth 12a formed on the rack shaft 12 with pinion teeth 17a formed on the pinion shaft 17. Further, tie rods 19 are rotatably connected to both ends of the rack shaft 12 via rack ends 18 which are ball joints provided at the shaft ends. The tip of the tie rod 19 is connected to a knuckle (not shown) to which the steered wheel 4 is assembled. Therefore, in the EPS 2, the rotation of the steering shaft 11 accompanying the steering operation is converted into an axial movement of the rack shaft 12 by the rack and pinion mechanism 14, and this axial movement is transmitted to the knuckle via the tie rod 19. The steering angle of the steered wheels 4, that is, the traveling direction of the vehicle is changed.

Note that the position of the rack shaft 12 where the rack end 18 abuts the left end of the rack housing 13 is the position where the maximum rightward steering is possible, and this position corresponds to the rack end position as the right end position. Further, the position of the rack shaft 12 where the rack end 18 abuts the right end of the rack housing 13 is the position where the steering can be steered to the left as much as possible, and this position corresponds to the rack end position as the left end position.

The EPS actuator 6 includes a motor 21 as a drive source and a speed reduction mechanism 22 such as a worm and wheel. The motor 21 is connected to the column shaft 15 via a speed reduction mechanism 22. Then, the EPS actuator 6 applies the motor torque to the steering mechanism 5 as an assist force by decelerating the rotation of the motor 21 using the deceleration mechanism 22 and transmitting it to the column shaft 15. Note that the motor 21 of this embodiment is a three-phase brushless motor.

The steering control device 1 is connected to a motor 21 and controls its operation. Note that the steering control device 1 includes a central processing unit (CPU) and a memory (not shown), and the CPU executes a program stored in the memory at every predetermined calculation cycle. As a result, various controls are executed.

Connected to the steering control device 1 are a vehicle speed sensor 31 that detects the vehicle speed SPD of the vehicle, and a torque sensor 32 that detects the steering torque Th applied to the steering shaft 11 by the driver's steering. Further, a rotation sensor 33 is connected to the steering control device 1 to detect the rotation angle θm of the motor 21 as a relative angle within a range of 360°. Note that the steering torque Th and the rotation angle θm are detected as positive values when the vehicle is steered to the right, and negative values when the vehicle is steered to the left, for example. Then, the steering control device 1 operates the EPS actuator 6 by supplying drive power to the motor 21 based on signals indicating each state quantity input from each of these sensors, that is, the steering mechanism 5 operates the rack shaft 12. The assist force applied to reciprocate is controlled.

Next, the configuration of the steering control device 1 will be explained.
As shown in FIG. 2, the steering control device 1 includes a microcomputer 41 as a motor control unit that outputs a motor control signal Sm, and a drive circuit 42 that supplies drive power to the motor 21 based on the motor control signal Sm. ing. Note that the drive circuit 42 of this embodiment employs a well-known PWM inverter having a plurality of switching elements such as FETs. The motor control signal Sm output from the microcomputer 41 defines the on/off state of each switching element. As a result, each switching element is turned on and off in response to the motor control signal Sm, and the energization pattern to the motor coil of each phase is switched, so that the DC power of the on-vehicle power supply 43 is converted to three-phase drive power, and the motor 21 is output to.

Each control block shown below is realized by a computer program executed by the microcomputer 41, and each state quantity is detected at a predetermined sampling period, and the control blocks shown below are executed at each predetermined calculation period. Each calculation process is executed.

The vehicle speed SPD, the steering torque Th, and the rotation angle θm of the motor 21 are input to the microcomputer 41. Further, the microcomputer 41 receives input of each phase current value Iu, Iv, Iw of the motor 21 detected by the current sensor 44 and the power supply voltage Vb of the on-vehicle power supply 43 detected by the voltage sensor 45. The current sensor 44 is provided on a connection line 46 between the drive circuit 42 and the motor coils of each phase. Voltage sensor 45 is provided on connection line 47 between vehicle-mounted power supply 43 and drive circuit 42 . In addition, in FIG. 2, for convenience of explanation, the current sensor 44 of each phase and the connection line 46 of each phase are shown together as one. Then, the microcomputer 41 outputs a motor control signal Sm based on each of these state quantities.

Specifically, the microcomputer 41 includes a current command value calculation unit 51 that calculates current command values Id*, Iq*, and a motor control signal generation unit 52 that outputs a motor control signal Sm based on the current command values Id*, Iq*. and an absolute steering angle detection section 53 that detects the absolute steering angle θs.

The current command value calculation unit 51 receives the steering torque Th, vehicle speed SPD, and absolute steering angle θs. The current command value calculating section 51 calculates current command values Id*, Iq* based on these state quantities. The current command values Id*, Iq* are target values of the current to be supplied to the motor 21, and indicate the current command value on the d-axis and the current command value on the q-axis in the d/q coordinate system, respectively. Among these, the q-axis current command value Iq* indicates the target value of the motor torque output by the motor 21. Note that in this embodiment, the d-axis current command value Id* is basically fixed to zero. The current command values Id* and Iq* are, for example, positive values when assisting rightward steering, and negative values when assisting leftward steering.

Current command values Id*, Iq*, phase current values Iu, Iv, Iw, and rotation angle θm of the motor 21 are input to the motor control signal generation unit 52. The motor control signal generating section 52 generates the motor control signal Sm by executing current feedback control in the d/q coordinate system based on these state quantities.

Specifically, the motor control signal generation unit 52 calculates the actual value of the motor 21 in the d/q coordinate system by mapping each phase current value Iu, Iv, Iw onto the d/q coordinate system based on the rotation angle θm. A d-axis current value Id and a q-axis current value Iq, which are current values, are calculated. The motor control signal generation unit 52 then generates current feedback in order to make the d-axis current value Id follow the d-axis current command value Id*, and to make the q-axis current value Iq follow the q-axis current command value Iq*. By performing the control, a motor control signal Sm is generated. Note that the q-axis current value Iq calculated in the process of generating the motor control signal Sm is output to the end position corresponding angle management section 65.

The motor control signal generation section 52 outputs the motor control signal Sm generated in this manner to the drive circuit 42. As a result, drive power corresponding to the motor control signal Sm is supplied to the motor 21, and motor torque corresponding to the q-axis current command value Iq* is output from the motor 21, so that an assist force is applied to the steering mechanism 5. Granted.

The rotation angle θm is input to the absolute steering angle detection section 53. The absolute steering angle detection unit 53 detects the motor absolute angle expressed as an absolute angle including a range exceeding 360° based on the rotation angle θm. The absolute steering angle detection unit 53 of this embodiment integrates the number of rotations of the motor 21 using the rotation angle θm as the origin when a starting switch such as an ignition switch is turned on for the first time after replacing the on-vehicle power supply 43, and calculates the rotation speed of the motor 21. The motor absolute angle is detected based on the number and rotation angle θm. Then, the absolute steering angle detection unit 53 detects the absolute steering angle θs indicating the steering angle of the steering shaft 11 by multiplying the motor absolute angle by a conversion coefficient based on the reduction ratio of the reduction gear mechanism 22. In the steering control device 1 of this embodiment, the presence or absence of rotation of the motor 21 is monitored even when the starting switch is turned off, and the number of rotations of the motor 21 is constantly integrated. As a result, even when the start switch is turned on for the second time after the on-vehicle power source 43 is replaced, the origin of the absolute steering angle θs is the same as the origin set when the start switch is turned on for the first time.

Note that since the steering angle of the steered wheels 4 is changed by the rotation of the steering shaft 11 as described above, the absolute steering angle θs indicates the rotation angle of the rotating shaft that can be converted into the steering angle of the steered wheels 4. . Further, the motor absolute angle and the absolute steering angle θs are, for example, positive values when the rotation angle is to the right from the origin, and negative values when the rotation angle is to the left.

Next, the configuration of the current command value calculation section 51 will be explained in detail.
The current command value calculation unit 51 includes an assist command value calculation unit 61 that calculates an assist command value Ias*, which is a basic component of the q-axis current command value Iq*, and an assist command value calculation unit 61 that calculates the upper limit of the absolute value of the q-axis current command value Iq*. It includes a limit value setting section 62 that sets a limit value Ig, and a guard processing section 63 that limits the absolute value of the assist command value Ias* to be equal to or less than the limit value Ig. Further, the current command value calculation unit 51 includes an end position corresponding angle management unit 65 that manages end position corresponding angles θs_le and θs_re, which are absolute steering angles θs corresponding to the left and right rack end positions stored in the memory 64. There is.

The steering torque Th and vehicle speed SPD are input to the assist command value calculation section 61. The assist command value calculating section 61 calculates the assist command value Ias* based on the steering torque Th and the vehicle speed SPD. Specifically, the assist command value calculating section 61 calculates the assist command value Ias* having a larger absolute value as the absolute value of the steering torque Th is larger and as the vehicle speed SPD is lower. The assist command value Ias* calculated in this way is output to the guard processing section 63.

In addition to the assist command value Ias*, the guard processing section 63 receives a limit value Ig set in the limit value setting section 62 as described later. When the absolute value of the input assist command value Ias* is less than or equal to the limit value Ig, the guard processing unit 63 directly sets the value of the assist command value Ias* to the q-axis current command value Iq* and outputs it to the motor control signal generating unit 52. Output to. On the other hand, when the absolute value of the input assist command value Ias* is larger than the limit value Ig, the value obtained by limiting the absolute value of the assist command value Ias* to the value of the limit value Ig is set as the q-axis current command value Iq*. The signal is output to the motor control signal generation section 52 as a signal.

The memory 64 stores a rated current Ir as a maximum current corresponding to a preset motor torque that the motor 21 can output, end position corresponding angles θs_le, θs_re, etc. The left end position corresponding angle θs_le is the absolute steering angle θs corresponding to the left rack end position, and the right end position corresponding angle θs_re is the absolute steering angle θs corresponding to the right rack end position. The setting and updating of the end position corresponding angles θs_le and θs_re are managed by the end position corresponding angle management unit 65 as described later. Note that the memory 64 of this embodiment is of a type that retains the end position corresponding angles θs_le and θs_re unless, for example, the on-vehicle power source 43 is removed.

Next, the configuration of the limit value setting section 62 will be explained.
The limit value setting unit 62 receives the absolute steering angle θs, vehicle speed SPD, power supply voltage Vb, rated current Ir, and end position corresponding angles θs_le and θs_re. Then, the limit value setting unit 62 sets the limit value Ig based on these state quantities.

Specifically, as shown in FIG. 3, the limit value setting section 62 includes a steering angle limit value calculation section 71 that calculates a steering angle limit value Ien based on the absolute steering angle θs, and a steering angle limit value calculation section 71 that calculates a steering angle limit value Ien based on the absolute steering angle θs, and a steering angle limit value calculation section 71 that calculates a steering angle limit value Ien based on the absolute steering angle θs. , and a minimum value selection section 73 that selects the smaller of the steering angle limit value Ien and the voltage limit value Ivb.

The absolute steering angle θs, vehicle speed SPD, rated current Ir, and end position corresponding angles θs_le and θs_re are input to the steering angle limit value calculation unit 71. Based on these state quantities, the steering angle limit value calculation unit 71 determines that the end separation angle Δθ, which indicates the minimum distance of the absolute steering angle θs from the left and right end position corresponding angles θs_le and θs_re, is less than or equal to a predetermined angle θ1, as described later. In this case, a steering angle limit value Ien that becomes smaller based on a decrease in the end separation angle Δθ is calculated. The steering angle limit value Ien calculated in this manner is output to the minimum value selection section 73. Note that the steering angle limit value calculating section 71 does not calculate the steering angle limit value Ien when neither the left and right end position corresponding angles θs_le nor θs_re are set in the memory 64.

The power supply voltage Vb is input to the voltage limit value calculation section 72. The voltage limit value calculation unit 72 calculates a voltage limit value Ivb smaller than the rated voltage for supplying the rated current Ir when the absolute value of the power supply voltage Vb becomes equal to or less than a preset voltage threshold value Vth. Specifically, when the absolute value of the power supply voltage Vb becomes equal to or less than the voltage threshold Vth, the voltage limit value calculation unit 72 calculates a voltage limit value having a smaller absolute value based on the decrease in the absolute value of the power supply voltage Vb. Calculate Ivb. The voltage limit value Ivb calculated in this way is output to the minimum value selection section 73.

The minimum value selection section 73 selects the smaller of the input steering angle limit value Ien and voltage limit value Ivb as the limit value Ig, and outputs it to the guard processing section 63.
Then, by outputting the steering angle limit value Ien to the guard processing unit 63 as the limit value Ig, the absolute value of the q-axis current command value Iq* is limited to the steering angle limit value Ien. As a result, when the end separation angle Δθ is less than or equal to the predetermined angle θ1, the absolute value of the q-axis current command value Iq* is reduced based on the decrease in the end separation angle Δθ, thereby alleviating the impact on the end contact. End hit relaxation control is executed. As will be described later, if both the left and right end position corresponding angles θs_le and θs_re are stored in the memory 64, this is normal end application relaxation control, and the memory 64 stores either the left or right end position corresponding angles θs_le and θs_re. If it is stored, it becomes provisional end hit relaxation control.

Further, by outputting the voltage limit value Ivb to the guard processing unit 63 as the limit value Ig, the absolute value of the q-axis current command value Iq* is limited to the voltage limit value Ivb. As a result, when the absolute value of the power supply voltage Vb becomes equal to or lower than the voltage threshold Vth, power supply protection control is executed to reduce the absolute value of the q-axis current command value Iq* based on the decrease in the absolute value of the power supply voltage Vb. Ru.

Next, the configuration of the steering angle limit value calculation section 71 will be explained.
The steering angle limit value calculation unit 71 includes an end separation angle calculation unit 81 that calculates an end separation angle Δθ, and an angle restriction component calculation unit 82 that calculates an angle restriction component Iga that is a current limit amount determined according to the end separation angle Δθ. It is equipped with The steering angle limit value calculation unit 71 also includes an excess angular velocity calculation unit 83 that calculates an excess angular velocity ωo that is the excess of the steering speed ωs with respect to the upper limit angular velocity ωlim, and a speed limit that is a current limit amount that is determined according to the excess angular velocity ωo. The speed limit component calculating section 84 calculates the component Igs.

Specifically, the end separation angle calculating section 81 receives the absolute steering angle θs and the end position corresponding angles θs_le and θs_re. If both left and right end position corresponding angles θs_le and θs_re are stored in the memory 64, the end separation angle calculation unit 81 calculates the difference between the absolute steering angle θs and the left end position corresponding angle θs_le in the latest calculation cycle. and the difference between the absolute steering angle θs and the right end position corresponding angle θs_re in the latest calculation cycle. Then, the end separation angle calculation unit 81 outputs the smaller absolute value of the calculated differences to the angle limit component calculation unit 82 and the excess angular velocity calculation unit 83 as the end separation angle Δθ. On the other hand, if the end position corresponding angles θs_le and θs_re of only one of the left and right sides are stored in the memory 64, the end separation angle calculation unit 81 calculates the absolute steering angle θs and the end position corresponding angle in the latest calculation cycle. The difference between θs_le or the end position corresponding angle θs_re is calculated. Then, the end separation angle calculation unit 81 outputs this difference as the end separation angle Δθ to the angle limit component calculation unit 82 and the excess angular velocity calculation unit 83.

Note that the end separation angle calculating section 81 does not calculate the end separation angle Δθ when neither the left and right end position corresponding angles θs_le and θs_re are stored in the memory 64. As a result, the angle limit component Iga and the excess angular velocity ωo are not calculated in the angle limit component calculation unit 82 and the excess angular velocity calculation unit 83, which will be described later, and the steering angle limit value Ien is not calculated.

The end separation angle Δθ and the vehicle speed SPD are input to the angle limit component calculation unit 82. The angle restriction component calculation unit 82 is equipped with a map that defines the relationship between the end separation angle Δθ, the vehicle speed SPD, and the angle restriction component Iga, and by referring to the map, it calculates the angle according to the end separation angle Δθ and the vehicle speed SPD. Calculate the limiting component Iga.

In this map, the angle limiting component Iga decreases from a state where the end separation angle Δθ is zero in proportion to its increase, and the end separation angle Δθ reaches zero at a predetermined angle θ1, and the end separation angle Δθ becomes smaller than the predetermined angle θ1. It is set so that if it becomes large, it becomes zero. In addition, this map also sets a region where the end separation angle Δθ is negative, and when the end separation angle Δθ becomes smaller than zero, the angle limiting component Iga increases in proportion to the decrease, and the rated current Ir After reaching the same value, it remains constant. The negative region in the map assumes that the EPS 2 is elastically deformed and the motor 21 is rotated by further performing cutting steering from the state where the rack end 18 is in contact with the rack housing 13. Note that the predetermined angle θ1 is set to a small angle indicating a range near the end position corresponding angles θs_le and θs_re. That is, the angle restriction component Iga becomes smaller as the absolute steering angle θs moves toward the steering neutral side from the end position corresponding angles θs_le, θs_re, and when it is closer to the steering neutral position than near the end position corresponding angles θs_le, θs_re, It is set to zero.

Further, this map is set so that in a region where the end separation angle Δθ is less than or equal to a predetermined angle θ1, the angle limiting component Iga becomes smaller based on an increase in the vehicle speed SPD. Specifically, when the vehicle speed SPD is in a low speed range, the angle restriction component Iga is set to be greater than zero, but when the vehicle speed SPD is in a medium to high speed range, the angle restriction component Iga is set to be zero. . The angle limiting component Iga calculated in this way is output to the subtracter 85.

The steering speed ωs obtained by differentiating the end separation angle Δθ and the absolute steering angle θs is input to the excess angular velocity calculation unit 83. Then, the excess angular velocity calculating section 83 calculates the excess angular velocity ωo based on these state quantities.

Specifically, the excess angular velocity calculation unit 83 includes an upper limit angular velocity calculation unit 86 that calculates the upper limit angular velocity ωlim. The end separation angle Δθ is input to the upper limit angular velocity calculation unit 86. The upper limit angular velocity calculating section 86 includes a map that defines the relationship between the end separation angle Δθ and the upper limit angular velocity ωlim, and calculates the upper limit angular velocity ωlim according to the end separation angle Δθ by referring to the map.

In this map, the upper limit angular velocity ωlim is set such that the upper limit angular velocity ωlim is the smallest when the end separation angle Δθ is larger than zero and is near zero, and the upper limit angular velocity ωlim increases in proportion to the increase in the end separation angle Δθ. has been done. Further, the upper limit angular velocity ωlim is set so that when the end separation angle Δθ becomes larger than a predetermined angle θ2, the upper limit angular velocity ωlim becomes constant at a preset value as the maximum angular velocity at which the motor 21 can rotate. Note that the predetermined angle θ2 is set to a larger angle than the predetermined angle θ1.

When the absolute value of the steering speed ωs is larger than the upper limit angular velocity ωlim according to the end separation angle Δθ, the excess angular velocity calculation unit 83 calculates the speed limit component by using the excess of the steering speed ωs over the upper limit angular velocity ωlim as the excess angular velocity ωo. It is output to section 84. On the other hand, if the absolute value of the steering speed ωs is less than or equal to the upper limit angular velocity ωlim, the excess angular velocity calculation unit 83 outputs an excess angular velocity ωo indicating zero to the speed limit component calculation unit 84.

Specifically, the excess angular velocity calculation unit 83 includes a minimum value selection unit 87 into which the upper limit angular velocity ωlim and the steering speed ωs are input. The minimum value selection unit 87 selects the smaller of the absolute values of the upper limit angular velocity ωlim and the steering speed ωs, and outputs the selected value to the subtracter 88. Then, the excess angular velocity calculation section 83 calculates the excess angular velocity ωo by subtracting the output value of the minimum value selection section 87 from the absolute value of the steering speed ωs in the subtracter 88. By selecting the smaller of the absolute values of the upper limit angular velocity ωlim and the steering speed ωs in the minimum value selection unit 87 in this manner, when the steering speed ωs is less than or equal to the upper limit angular velocity ωlim, the subtracter 88 selects the steering speed ωs. The steering speed ωs is subtracted from the angular velocity ωo, and the excess angular velocity ωo becomes zero. On the other hand, if the steering speed ωs is larger than the upper limit angular speed ωlim, the subtracter 88 subtracts the upper limit angular speed ωlim from the absolute value of the steering speed ωs, and the excess angular speed ωo is the excess of the steering speed ωs with respect to the upper limit angular speed ωlim. becomes.

The excess angular velocity ωo and the vehicle speed SPD are input to the speed limit component calculation unit 84. The speed limit component calculation unit 84 is equipped with a map that defines the relationship between the excess angular velocity ωo, the vehicle speed SPD, and the speed limit component Igs, and by referring to the map, the speed limit component according to the excess angular velocity ωo and the vehicle speed SPD is determined Calculate Igs.

In this map, the speed limit component Igs is set such that the speed limit component Igs is the smallest when the excess angular velocity ωo is zero, and the speed limit component Igs increases in proportion to the increase in the excess angular velocity ωo. Further, this map is set so that the speed limit component Igs becomes smaller based on an increase in the vehicle speed SPD. Note that in this map, the absolute value of the speed limit component Igs is set to be smaller than the absolute value of the angle limit component Iga. The speed limit component Igs calculated in this manner is output to the subtracter 89.

The rated current Ir is input to the subtracter 85 to which the above-mentioned angle limiting component Iga is input. The steering angle limit value calculation unit 71 outputs a value obtained by subtracting the angle limit component Iga from the rated current Ir in the subtracter 85 to the subtracter 89 to which the speed limit component Igs is input. Then, in the subtracter 89, the steering angle limit value calculation unit 71 calculates a value obtained by subtracting the speed limit component Igs from the output value of the subtracter 85, that is, a value obtained by subtracting the angle limit component Iga and the speed limit component Igs from the rated current Ir. is output to the minimum value selection section 73 as the steering angle limit value Ien.

Next, the configuration of the end position corresponding angle management section 65 will be explained.
As shown in FIG. 2, a motor angular velocity ωm obtained by differentiating the steering torque Th, the absolute steering angle θs, and the rotation angle θm is input to the end position corresponding angle management unit 65. The end position corresponding angle management unit 65 manages the storage and updating of the end position corresponding angles θs_le and θs_re in the memory 64 based on these state quantities.

The end position corresponding angle management unit 65 mainly performs the following two processes.
(1) The end position corresponding angles θs_le and θs_re are newly stored in the memory 64, including when updating them.

(2) Determine whether it is necessary to update the end position corresponding angles θs_le and θs_re stored in the memory 64.
In both processes (1) and (2), the end position corresponding angle management unit 65 determines whether movement of the rack shaft 12 to either the left or right side is restricted, and determines whether the movement of the rack shaft 12 is restricted. A plurality of absolute steering angles θs at the time when it is determined that the steering angle is set are obtained as regulation position determination angles θi (i is a natural number). Then, the end position corresponding angle management unit 65 executes each of the processes (1) and (2) based on the plurality of restriction position determination angles θi.

In the process (1), when the left and right regulation position determination angles θi are obtained, the end position correspondence angle management unit 65 determines the end position correspondence angle θs_le based on the left and right regulation position determination angles θi. , θs_re are stored in the memory 64.

On the other hand, when the end position corresponding angle management unit 65 acquires a plurality of restriction position determination angles θi only for the left side or the right side, the end position corresponding angle management unit 65 determines the end position of the left or right side based on the plurality of restriction position determination angles θi for the left side or the right side. The position corresponding angles θs_le and θs_re are stored in the memory 64. In this process, as will be described later, the end position corresponding angle management unit 65 determines whether these restriction position determination angles θi are the movement of the rack shaft 12 due to the end contact, based on the distribution of a plurality of restriction position determination angles θi on the left or right side. Determine whether the data is from when the data was regulated. Then, when the movement of the rack shaft 12 is regulated by the end abutment, the angle based on the end abutment determination data D1 and D2 consisting of a plurality of regulation position determination angles θi on the left or right side is calculated as the end position corresponding angle θs_le on the left side or the angle θs_le on the right side. It is stored in the memory 64 as the end position corresponding angle θs_re.

In the process (2), the end position corresponding angle management unit 65 acquires a plurality of left or right restriction position determination angles θi, and based on the variance of these plurality of restriction position determination angles θi, It is determined whether the position determination angle θi is data obtained when the movement of the rack shaft 12 is restricted by end contact. Then, the end position corresponding angle management unit 65 updates the end position corresponding angles θs_le and θs_re when the plurality of regulation position determination angles θi are data when the movement of the rack shaft 12 is regulated by the end abutment. To give permission. On the other hand, the end position corresponding angle management unit 65 allows updating of the end position corresponding angles θs_le and θs_re if the plurality of restriction position determination angles θi are not data when the movement of the rack shaft 12 is regulated by end contact. do not. In addition, the end position corresponding angle management unit 65 determines whether the end contact relaxation control is being executed normally even if the plurality of restriction position determination angles θi are data when the movement of the rack shaft 12 is restricted by the end contact. In this case, updating of the end position corresponding angles θs_le and θs_re is not permitted.

Specifically, as shown in FIG. 4, the end position corresponding angle management unit 65 includes an angular velocity change amount calculation unit 91, a first restriction determination unit 92 as a restriction determination unit, a second restriction determination unit 93, and a variance determination unit. 94, an update permission section 95, and an end position corresponding angle setting section 96. Each control block will be explained in turn below.

(Angular velocity change calculation unit 91)
The motor angular velocity ωm is input to the angular velocity change amount calculation unit 91. The angular velocity change amount calculation unit 91 calculates the angular velocity change amount Δωm, which is the amount of change, based on the input motor angular velocity ωm. Then, the angular velocity change amount calculation section 91 outputs the angular velocity change amount Δωm to the first regulation determination section 92 and the second regulation determination section 93. Note that the angular velocity change amount calculation unit 91 of the present embodiment performs low-pass filter processing on the angular velocity change amount Δωm and outputs the result to the first regulation determination unit 92 and the second regulation determination unit 93.

(First regulation determination unit 92)
The first regulation determination unit 92 receives the steering torque Th, the motor angular velocity ωm, and the angular velocity change amount Δωm. The first restriction determination unit 92 performs two determinations, a dynamic restriction determination and a static restriction determination, in parallel or consecutively based on these state quantities, thereby determining whether the rack shaft 12 is placed on either the left or right side. Determine whether the movement of the person is restricted. The static restriction determination is a determination that detects a state in which the steering is held while the movement of the rack shaft 12 is restricted, and a state in which the movement of the rack shaft 12 is restricted by performing slow steering. The dynamic restriction determination is a determination that detects a state in which the turning steering is performed at a relatively high speed and the turning steering is performed immediately after the movement of the rack shaft 12 is restricted.

The first restriction determination unit 92 determines that the dynamic restriction determination is satisfied and the movement of the rack shaft 12 is restricted when the following three conditions are satisfied.
(a1) The absolute value of the steering torque Th is greater than or equal to the first steering torque threshold Tth1.

(a2) The sign of the motor angular velocity ωm is the same as the sign of the steering torque Th, and the absolute value of the motor angular velocity ωm is greater than the first angular velocity threshold ωth1.
(a3) The sign of the angular velocity change Δωm is opposite to the sign of the steering torque Th, and the absolute value of the angular velocity change Δωm is greater than the first angular velocity change threshold Δωth1.

Note that the first steering torque threshold Tth1 is a steering torque when performing return steering immediately after the rack end 18 contacts the rack housing 13, and is set to an appropriate value larger than zero. The first angular velocity threshold value ωth1 is an angular velocity indicating that the motor 21 is stopped, and is set to approximately zero. The first angular velocity change amount threshold Δωth1 is an angular velocity change amount that indicates that the motor 21 is rapidly decelerating, and is set to a relatively large value.

Next, an example of a processing procedure for dynamic restriction determination by the first restriction determination section 92 will be described according to the flowchart shown in FIG. In addition, for convenience of explanation, in the following, a case will be explained in which the rack shaft 12 moves to the right and the right regulation position determination angle θi is obtained; however, when the rack shaft 12 moves to the left and the left regulation position determination angle Similar processing is performed when obtaining θi.

Specifically, upon acquiring various state quantities (step 101), the first regulation determination unit 92 determines whether the steering torque Th is greater than or equal to the first steering torque threshold Tth1 (step 102). If the steering torque Th is greater than or equal to the first steering torque threshold Tth1 (step 102: YES), it is determined whether the motor angular velocity ωm is greater than the first angular velocity threshold ωth1 (step 103). That is, in step 103, it is determined whether the sign of the motor angular velocity ωm is the same as the sign of the steering torque Th and the absolute value of the motor angular velocity ωm is greater than the first angular velocity threshold ωth1. If the motor angular velocity ωm is greater than the first angular velocity threshold ωth1 (step 103: YES), it is determined whether the angular velocity variation Δωm is less than the negative first angular velocity variation threshold Δωth1 (step 104). That is, in step 104, it is determined whether the sign of the angular velocity change Δωm is opposite to the sign of the steering torque Th, and the absolute value of the angular velocity change Δωm is larger than the first angular velocity change threshold Δωth1. If the angular velocity change amount Δωm is less than the negative first angular velocity change amount threshold Δωth1 (step 104: YES), it is determined that the dynamic restriction determination is established and the movement of the rack shaft 12 is restricted. , outputs the first regulation determination signal Sr1 indicating that to the dispersion determination section 94 (step 105).

On the other hand, if the steering torque Th is less than the first steering torque threshold Tth1 (step 102: NO), and if the motor angular velocity ωm is less than or equal to the first angular velocity threshold ωth1 (step 103: NO), the angular velocity change amount Δωm is If the amount of change in angular velocity is equal to or greater than the threshold value Δωth1 (step 104: NO), subsequent processing is not executed.

The first restriction determination unit 92 determines that the static restriction determination is satisfied and the movement of the rack shaft 12 is restricted when the following three conditions are satisfied.
(b1) The absolute value of the steering torque Th is greater than or equal to the second steering torque threshold Tth2.

(b2) The sign of the motor angular velocity ωm is the same as the sign of the steering torque Th, and the absolute value of the motor angular velocity ωm is greater than the first angular velocity threshold ωth1 and less than or equal to the second angular velocity threshold ωth2.

(b3) The absolute value of the angular velocity change amount Δωm is less than the second angular velocity change amount threshold Δωth2.
The second steering torque threshold Tth2 is the steering torque required to keep the steering wheel 3 steered when the vehicle is turned while the rack end 18 is in contact with the rack housing 13, and is the first steering torque. It is set to an appropriate value larger than the threshold Tth1. The second angular velocity threshold value ωth2 is an angular velocity indicating that the motor 21 is rotating at a low speed, and is set to an appropriate value greater than zero. The second angular velocity change amount threshold Δωth2 is an angular velocity change amount indicating that the motor 21 is not substantially accelerating or decelerating, and is set to a value smaller than the first angular velocity change amount threshold Δωth1 and slightly larger than zero. There is.

Next, an example of a processing procedure for static restriction determination by the first restriction determination section 92 will be described according to the flowchart shown in FIG. In addition, for convenience of explanation, in the following, a case will be explained in which the rack shaft 12 moves to the right and the right regulation position determination angle θi is obtained; however, when the rack shaft 12 moves to the left and the left regulation position determination angle Similar processing is performed when obtaining θi.

Specifically, upon acquiring various state quantities (step 201), the first regulation determination unit 92 determines whether the steering torque Th is greater than or equal to the second steering torque threshold Tth2 (step 202). If the steering torque Th is greater than or equal to the second steering torque threshold Tth2 (step 202: YES), it is determined whether the motor angular velocity ωm is greater than the first angular velocity threshold ωth1 and less than or equal to the second angular velocity threshold ωth2. (Step 203). That is, in step 203, it is determined whether the sign of the motor angular velocity ωm is the same as the sign of the steering torque Th, and the absolute value of the motor angular velocity ωm is greater than the first angular velocity threshold ωth1 and less than or equal to the second angular velocity threshold ωth2. Determine whether When the motor angular velocity ωm is greater than the first angular velocity threshold ωth1 and less than the second angular velocity threshold ωth2, that is, when the motor 21 is rotating at an extremely low speed (step 203: YES), the angular velocity change amount Δωm It is determined whether the absolute value is less than the second angular velocity change amount threshold value Δωth2 (step 204). If the absolute value of the angular velocity change amount Δωm is less than the second angular velocity change amount threshold Δωth2 (step 204: YES), it is determined that the static restriction determination is established and the movement of the rack shaft 12 is restricted. Then, a first regulation determination signal Sr1 indicating this is output to the dispersion determination section 94 (step 205).

On the other hand, if the steering torque Th is less than the second steering torque threshold Tth2 (step 202: NO), or if the motor angular velocity ωm is less than or equal to the first angular velocity threshold ωth1 or greater than the second angular velocity threshold ωth2 (step 203: If the absolute value of the angular velocity change amount Δωm is greater than or equal to the second angular velocity change amount threshold Δωth2 (step 204: NO), the subsequent processing is not executed.

(Second regulation determination unit 93)
As shown in FIG. 4, the steering torque Th, motor angular velocity ωm, and angular velocity change amount Δωm are input to the second regulation determination unit 93. The second restriction determination unit 93 performs a static restriction determination based on these state quantities to determine whether movement of the rack shaft 12 to either the left or right is restricted by executing the end application or end application relaxation control. Determine whether or not there is. The static restriction determination by the second restriction determination section 93 is performed by the same processing procedure as the static restriction determination by the first restriction determination section 92 described above. Then, when determining that the movement of the rack shaft 12 is restricted due to execution of the end contact or end contact relaxation control, the second restriction determination unit 93 updates the second restriction determination signal Sr2 indicating this. 95.

(Dispersion determination unit 94)
The steering torque Th, the absolute steering angle θs, the q-axis current value Iq, the angular velocity change amount Δωm, and the first regulation determination signal Sr1 are input to the dispersion determination unit 94. The dispersion determination unit 94 obtains a plurality of restriction position determination angles θi corresponding to the absolute steering angle θs when the first restriction determination unit 92 determines that the movement of the rack shaft 12 is restricted. The dispersion determination unit 94 of this embodiment is based on the mechanical elastic deformation of the EPS 2 caused by the torque applied to the EPS 2 with respect to the absolute steering angle θs when it is determined that the movement of the rack shaft 12 is restricted. Then, the angle after the stiffness compensation is obtained as the regulation position determination angle θi. The dispersion determination unit 94 determines, based on the dispersion of the left or right side restriction position determination angles θi, whether these are data when the movement of the rack shaft 12 is restricted by the end abutment. Then, when the plurality of restriction position determination angles θi are data when the movement of the rack shaft 12 is regulated by end contact, the dispersion determination unit 94 performs an end contact determination based on the plurality of restriction position determination angles θi. The data D1 is output to the end position corresponding angle setting section 96.

First, stiffness compensation will be explained.
The dispersion determination unit 94 obtains the value obtained by subtracting the mechanical elastic deformation occurring in the EPS 2 from the absolute steering angle θs at the time when it is determined that the movement of the rack shaft 12 is restricted, as the restriction position determination angle θi. .

Specifically, the dispersion determination unit 94 calculates the pinion shaft torque Tp, which is the total value of the torques applied to the EPS 2 when it is determined that the movement of the rack shaft 12 is restricted. Note that the pinion shaft torque Tp corresponds to the axial force acting on the rack shaft 12, and the dispersion determination section 94 corresponds to an axial force detection section. The dispersion determination unit 94 of the present embodiment calculates the steering torque Th applied to the driver, the motor torque based on the q-axis current value Iq, and the angular velocity change amount Δωm of the motor 21, as shown in the following equation (1). The pinion shaft torque Tp is calculated using the based inertia torque.

Tp=Th+Iq×Km+Δωm×Kω…(1)
Note that "Km" indicates a coefficient determined by the motor constant of the motor 21, the reduction ratio and efficiency of the reduction mechanism 22, etc. “Kω” indicates a coefficient determined by the moment of inertia of the motor 21, the reduction ratio and efficiency of the reduction mechanism 22, and the like.

Here, as shown in FIG. 7, when the driver performs a steering operation, the steered wheels 4 are steered according to the pinion shaft torque Tp applied to the EPS 2, and the absolute steering angle θs increases. Then, from a point slightly exceeding the absolute steering angle θs corresponding to the actual rack end position, the absolute steering angle θs hardly increases even if the pinion shaft torque Tp increases. This is because the movement of the rack shaft 12 is restricted by the end abutment, and the pinion shaft torque Tp increases, resulting in mechanical elastic deformation such as twisting of the steering shaft 11 constituting the EPS 2 and compression of the rack shaft 12. This is because the motor 21 only rotates slightly. Since the slope of the pinion shaft torque Tp with respect to the absolute steering angle θs is proportional to the elastic coefficient Ke of the EPS2, the absolute steering angle θs is determined according to the slope based on the absolute steering angle θs at the position where the pinion shaft torque Tp becomes zero. almost matches the actual rack end position.

Based on this, the dispersion determination unit 94 calculates the rotation angle of the motor 21 based on the amount of elastic deformation of the EPS 2 by multiplying the elastic coefficient Ke of the EPS 2 by the pinion shaft torque Tp. Then, the dispersion determination unit 94 obtains a value obtained by subtracting the rotation angle from the absolute steering angle θs at the time when the movement of the rack shaft 12 is determined to be restricted, as the restriction position determination angle θi.

Next, a description will be given of determining whether the left or right side restriction position determination angles θi are data when the movement of the rack shaft 12 is restricted by end contact. In the following, for convenience of explanation, a case will be described in which leftward movement of the rack shaft 12 is restricted multiple times and a plurality of left restriction position determination angles θi are obtained, but the right restriction position determination angle Similar processing is performed when a plurality of θi are obtained.

The dispersion determination unit 94 determines, as a restriction position determination angle, an angle obtained by performing rigidity compensation on the absolute steering angle θs in the calculation cycle in which the first restriction determination signal Sr1 indicating that the movement of the rack shaft 12 is restricted is input. Obtain as θi. The dispersion determining unit 94 determines whether the direction in which movement of the rack shaft 12 is restricted is to the left or to the right, based on the sign of the absolute steering angle θs. Then, when acquiring a plurality of left regulation position determination angles θi, the variance determination unit 94 uses the following equation (1) as a determination variance value to be determined each time it acquires a left regulation position determination angle θi. The first judgment variance value Vd1 of is calculated.

Note that "n" indicates the number of acquired restriction position determination angles θi, and is an integer of 2 or more. That is, the dispersion determination unit 94 of this embodiment calculates the first determination dispersion value Vd1 when two or more regulation position determination angles θi are obtained. "i" is a natural number. “θave” is the average value of the obtained restriction position determination angles θi.

Subsequently, the dispersion determining unit 94 calculates a first dispersion ratio Rd1 (Rd1=Vd1/Vm), which is a ratio between the first determined dispersion value Vd1 and a preset predetermined dispersion value Vm. The predetermined dispersion value Vm is based on a plurality of restriction position determination angles θi when the movement of the rack shaft 12 is actually restricted by end contact under an environment where it can be visually confirmed that the rack end 18 is in contact with the rack housing 13. This is the variance value obtained and calculated using the above equation (1).

Here, if the movement of the rack shaft 12 is restricted by hitting a curb, for example, the position of the rack shaft 12 changes depending on the situation when the steered wheels 4 hit the curb, so the size of the restriction position determination angle θi is It becomes more likely to fluctuate. On the other hand, when the movement of the rack shaft 12 is restricted by the end abutment, the position of the rack shaft 12 is determined depending on the structure of the EPS 2, etc., so that the magnitude of the restriction position determination angle θi is less likely to vary. Therefore, if the variance of the plurality of restriction position determination angles θi is large, it is considered that the movement of the rack shaft 12 is restricted by hitting a curb or the like. On the other hand, if the variance of the plurality of restriction position determination angles θi is small, it is considered that the movement of the rack shaft 12 is restricted by the end abutment.

Based on this point, the dispersion determination unit 94 compares the first dispersion ratio Rd1 with a dispersion threshold value Rthn that is set according to the number n of acquired regulation position determination angles θi. The dispersion threshold value Rthn is set in advance so that the larger the number n of acquisitions is, the smaller the value becomes. Then, when the first dispersion ratio Rd1 is equal to or less than the dispersion threshold Rthn, the dispersion determination unit 94 determines that the plurality of restriction position determination angles θi are data acquired when the movement of the rack shaft 12 was restricted by the end contact. Then, end hit determination data D1 consisting of the plurality of regulation position determination angles θi is output to the end position corresponding angle setting section 96.

On the other hand, if the first dispersion ratio Rd1 is larger than the dispersion threshold Rthn, the dispersion determination unit 94 determines that the plurality of restriction position determination angles θi are based on the data acquired when the movement of the rack shaft 12 is restricted by the end contact. It is determined that there is no end contact determination data D1 and the end contact determination data D1 is not output to the end position corresponding angle setting section 96. Further, the dispersion determination unit 94 determines a preset upper limit number of times that the plurality of restriction position determination angles θi are consecutively determined not to be data obtained when movement of the rack shaft 12 is restricted by end contact. If the limit position determination angle θi is exceeded, the plurality of acquired restriction position determination angles θi are discarded and the above process is repeated. Note that the upper limit number of times is set to "5", for example.

Specifically, as shown in the flowchart of FIG. 8, when the dispersion determination unit 94 acquires various state quantities (step 301), the first restriction determination signal Sr1 is input, and a new left restriction position determination angle θi is input. is obtained (step 302). If the left regulation position determination angle θi has not been newly acquired (step 302: NO), the subsequent processing is not executed. On the other hand, if the left-side restriction position determination angle θi is newly acquired (step 302: YES), the count value Cr of the acquisition counter indicating the number n of acquired restriction position determination angles θi is incremented (step 303).

Subsequently, the variance determining unit 94 determines whether or not the count value Cr of the acquisition counter is "2" (step 304), and if the count value Cr is "2" (step 304: YES). , the first determination variance value Vd1 is calculated using the above equation (1), and the first variance ratio Rd1 is calculated (step 305). Next, a comparison is made between the first dispersion ratio Rd1 and the dispersion threshold Rth2 when the number n of acquired regulation position determination angles θi is "2" (step 306). If the first dispersion ratio Rd1 is equal to or less than the dispersion threshold Rth2 (step 306: YES), the end hit determination data D1 is output to the end position corresponding angle setting section 96 (step 307), and the obtained regulation position determination angle θi is discarded (step 308), and the count value Cr of the acquisition counter is cleared (step 309).

If the count value Cr is not "2" (step 304: NO), the dispersion determination unit 94 determines whether the count value Cr of the acquisition counter is "3" (step 310), and sets the count value Cr is "3" (step 310: YES), the first judgment variance value Vd1 is calculated using the above equation (1), and the first variance ratio Rd1 is calculated (step 311). Subsequently, a comparison is made between the first dispersion ratio Rd1 and the dispersion threshold Rth3 when the number n of acquired regulation position determination angles θi is "3" (step 312). If the first dispersion ratio Rd1 is equal to or less than the dispersion threshold Rth3 (step 312: YES), the processes of steps 307 to 309 are executed.

If the count value Cr is not "3" (step 310: NO), the variance determination unit 94 determines whether the count value Cr of the acquisition counter is "4" (step 313), and sets the count value Cr is "4" (step 313: YES), the first judgment variance value Vd1 is calculated using the above equation (1), and the first variance ratio Rd1 is calculated (step 314). Subsequently, a comparison is made between the first dispersion ratio Rd1 and the dispersion threshold Rth4 when the number n of acquired regulation position determination angles θi is "4" (step 315). If the first dispersion ratio Rd1 is equal to or less than the dispersion threshold Rth4 (step 315: YES), the processes of steps 307 to 309 are executed.

If the count value Cr is not "4" (step 313: NO), the dispersion determination unit 94 determines whether the count value Cr of the acquisition counter is equal to or greater than "5" (step 316). If the count value Cr is "5" or more (step 316: YES), the first judgment variance value Vd1 is calculated using the above formula (1), and the first variance ratio Rd1 is calculated (step 317). . Subsequently, a comparison is made between the first dispersion ratio Rd1 and the dispersion threshold Rth5 when the number n of acquired regulation position determination angles θi is "5" (step 318). If the first dispersion ratio Rd1 is equal to or less than the dispersion threshold Rth5 (step 318: YES), the processes of steps 307 to 309 are executed. Note that if the count value Cr is less than "5", that is, if the count value Cr is "1" (step 316: NO), the subsequent processing is not executed.

On the other hand, if the first dispersion ratio Rd1 is greater than the dispersion threshold Rth2 (step 306: NO), and if the first dispersion ratio Rd1 is greater than the dispersion threshold Rth3 (step 312: NO), the dispersion determination unit 94 If the dispersion ratio Rd1 is greater than the dispersion threshold Rth4 (step 315: NO), and if the first dispersion ratio Rd1 is greater than the dispersion threshold Rth5 (step 318: NO), the process moves to step 319. In step 319, a count value Ca of a rejection counter is incremented, which indicates the number of times it has been successively determined that the plurality of restriction position determination angles θi are not data obtained when the movement of the rack shaft 12 is restricted by end contact ( step 319). Subsequently, it is determined whether the count value Ca of the rejection counter is larger than a predetermined count value Ca indicating the upper limit number of times (step 320). If the count value Ca is larger than the predetermined count value Cth (step 320: YES), the count value Ca of the rejection counter is cleared (step 321), and the processes of steps 308 and 309 are executed. Note that if the count value Ca is less than or equal to the predetermined count value th (step 320: NO), the processes of steps 321, 308, and 309 are not executed.

(Update permission section 95)
As shown in FIG. 4, the update permission section 95 receives the steering torque Th, the absolute steering angle θs, the q-axis current value Iq, the angular velocity change amount Δωm, and the second regulation determination signal Sr2. The update permission unit 95 obtains a plurality of restriction position determination angles θi corresponding to the absolute steering angle θs when the second restriction determination unit 93 determines that the movement of the rack shaft 12 is restricted. The update permission unit 95 of this embodiment performs rigidity compensation on the absolute steering angle θs when it is determined that the movement of the rack shaft 12 is restricted, in the same manner as the dispersion determination unit 94, and calculates the angle after rigidity compensation. is obtained as the regulation position determination angle θi. In other words, the update permission section 95 corresponds to an axial force detection section. The update permission unit 95 determines whether or not these are data when the movement of the rack shaft 12 is restricted by the end abutment, based on the variance of the plurality of restriction position determination angles θi on the left side or the right side. When the plurality of restriction position determination angles θi are data when the movement of the rack shaft 12 is regulated by the end contact, the update permission unit 95 updates the end contact determination data D2 consisting of the plurality of restriction position determination angles θi. , and an update permission signal Sp to the end position corresponding angle setting section 96. The update permission signal Sp is a signal that allows the end position corresponding angle setting unit 96 to update the end position corresponding angles θs_le and θs_re stored in the memory 64.

In the following, for convenience of explanation, a case will be described in which leftward movement of the rack shaft 12 is restricted multiple times and a plurality of left restriction position determination angles θi are obtained, but the right restriction position determination angle Even when a plurality of θi are obtained, the update permission unit 95 performs similar processing.

The update permission unit 95 determines, as a restriction position determination angle, an angle obtained by performing rigidity compensation on the absolute steering angle θs in the calculation cycle in which the second restriction determination signal Sr2 indicating that the movement of the rack shaft 12 is restricted is input. At the same time, the pinion shaft torque Tp as the judgment shaft force input in the same calculation cycle is obtained in association with the regulation position judgment angle θi. The update permission unit 95 determines whether the direction in which movement of the rack shaft 12 is restricted is to the left or to the right, based on the sign of the absolute steering angle θs.

The regulation position determination angle θi obtained by the update permission unit 95 is classified into a plurality of axial force ranges set based on the magnitude of the pinion shaft torque Tp. Specifically, the update permission unit 95 of this embodiment includes, as the axial force ranges, a first axial force range in which the pinion axial torque Tp is small, a second axial force range in which the pinion axial torque Tp is medium, and a pinion axial force range in which the pinion axial torque Tp is medium. Three third axial force ranges in which the torque Tp is large are set. The update permission unit 95 classifies the obtained left regulation position determination angle θi into the first to third axial force ranges based on the pinion shaft torque Tp linked to the regulation position determination angle θi.

The update permission unit 95 updates the control position determination angle θi when the obtained number n of left-side restriction position determination angles θi exceeds a predetermined calculation number nca and acquires one or more restriction position determination angles classified into each of the first to third axial force ranges. , a second determination variance value Vd2 as a determination target variance value is calculated using the following equation (2). Note that in this embodiment, the predetermined number of calculations nca is "5".

Subsequently, the update permission unit 95 calculates a second dispersion ratio Rd2 (Rd2=Vd2/Vm) as a dispersion ratio that is a ratio between the second determined dispersion value Vd2 and a preset default dispersion value Vm.

Here, the restriction position determination angle θi obtained when it is determined that the movement of the rack shaft 12 is restricted by execution of the end contact relaxation control may vary depending on, for example, the magnitude of the road surface μ. On the other hand, the restriction position determination angle θi obtained when it is determined that the movement of the rack shaft 12 is restricted by the end abutment is mechanically determined according to the structure of the EPS 2, and is therefore less likely to vary. Therefore, when the variance of the plurality of restriction position determination angles θi is small, the movement of the rack shaft 12 cannot be restricted by executing the end contact relaxation control based on the stored end position corresponding angles θs_le and θs_re, and the end contact It is considered that the movement of the rack shaft 12 is restricted. In other words, it is considered that the stored end position corresponding angles θs_le and θs_re are shifted toward the steering neutral position with respect to the actual rack end angle, which is the actual end angle at which end contact actually occurs.

Based on this point, the update permission unit 95 compares the second dispersion ratio Rd2 and the dispersion threshold Rth5. The dispersion threshold Rth5 is a value when the acquisition number n is "5", and is set in advance. Then, when the second dispersion ratio Rd2 is equal to or less than the dispersion threshold Rth5, the update permission unit 95 determines that the plurality of restriction position determination angles θi are data acquired when the movement of the rack shaft 12 was restricted by the end contact. judge.

Subsequently, the update permission unit 95 calculates a temporary end position determination angle θe_t based on the plurality of restriction position determination angles θi determined to be data obtained when the movement of the rack shaft 12 was restricted by the end hit. do. The update permission unit 95 of this embodiment calculates the average value of the plurality of restriction position determination angles θi as the provisional end position determination angle θe_t.

The update permission unit 95 calculates the difference between the temporary end position determination angle θe_t and the left end position corresponding angle θs_le as the temporary end separation angle Δθ_t. Then, when the end separation angle Δθ is assumed to be the temporary end separation angle Δθ_t, the update permission unit 95 determines whether the q-axis current command value Iq*, which is limited by the execution of the end contact relaxation control, is equal to or less than the current threshold value Ith. For example, assuming that the end hit relaxation control is being executed normally, updating of the end position corresponding angles θs_le and θs_re is not permitted. The current threshold value Ith of this embodiment is a threshold value corresponding to the torque threshold value based on the rated torque, and is set to 50% of the rated current Ir.

Specifically, the update permission unit 95 is provided with a map that has the same tendency as the map included in the angle restriction component calculation unit 82 and is fixed when the vehicle speed SPD is zero. The update permission unit 95 calculates a temporary angle limit component Iga_t according to the temporary end separation angle Δθ_t by referring to the map. Then, when the temporary angle restriction component Iga_t is 50% or more of the rated current Ir, the update permission unit 95 determines that the q-axis current command value Iq* is less than or equal to the current threshold value Ith, and updates the end hit determination data D2 and The update permission signal Sp is not output to the end position corresponding angle setting section 96. Further, if the second dispersion ratio Rd2 is larger than the dispersion threshold Rth5, the update permission unit 95 determines that the plurality of regulation position determination angles θi are not data obtained when the movement of the rack shaft 12 is regulated by the end contact. It is determined that there is no end hit determination data D2 and the update permission signal Sp is not output to the end position corresponding angle setting section 96. After this, the update permission unit 95 discards the plurality of acquired restriction position determination angles θi, and repeats the above process.

Note that, as described above, the steering angle limit value Ien, which is the upper limit of the q-axis current command value Iq*, is calculated by subtracting the angle limit component Iga and the speed limit component Igs from the rated current Ir. Therefore, if the angle limiting component Iga is 50% or more of the rated current, the steering angle limiting value Ien will be 50% or less of the rated current, regardless of the magnitude of the speed limiting component Igs. If the temporary angle limiting component Iga_t is 50% or more of the rated current Ir, it is determined that the q-axis current command value Iq* is less than or equal to the current threshold value Ith.

On the other hand, if the temporary angle limit component Iga_t is less than 50% of the rated current Ir, the update permission section 95 outputs the end hit determination data D2 and the update permission signal Sp to the end position corresponding angle setting section 96. After this, the update permission unit 95 discards the plurality of acquired restriction position determination angles θi, and repeats the above process.

Specifically, as shown in the flowchart of FIG. 9, upon acquiring various state quantities (step 401), the update permission unit 95 regulates each of the first to third axial force ranges based on the pinion axial torque Tp. It is determined whether or not the position determination angle θi has been classified into at least one classification (step 402). Next, if at least one regulation position determination angle θi is classified into each of the first to third axial force ranges based on the pinion shaft torque Tp (step 402: YES), the regulation position determination angle θi It is determined whether or not the number of obtained items n is equal to or greater than a predetermined number of calculations nca (step 403). If at least one regulation position determination angle θi is not classified in each of the first to third axial force ranges based on the pinion shaft torque Tp (step 402: NO), and the number n of regulation position determination angles θi obtained is less than the predetermined number of calculations nca (step 403: NO), the subsequent processing is not executed.

If the number n of obtained regulation position determination angles θi is greater than or equal to the predetermined calculation number nca (step 403: YES), the update permission unit 95 calculates the second determination variance value Vd2 using the above equation (2). , a second dispersion ratio Rd2 is calculated (step 404). Next, the second dispersion ratio Rd2 and the dispersion threshold Rth5 are compared in magnitude (step 405), and if the second dispersion ratio Rd2 is less than or equal to the dispersion threshold Rth5 (step 405: YES), the temporary end position determination angle θe_t is calculated (step 406), and a temporary end separation angle Δθ_t is calculated (step 407). Then, a temporary angle limit component Iga_t at the temporary end separation angle Δθ_t is calculated (step 408), and it is determined whether the temporary angle limit component Iga_t is 50% or more of the rated current Ir (step 409).

If the temporary angle limit component Iga_t is less than 50% of the rated current Ir (step 409: NO), the update permission section 95 outputs the update permission signal Sp and the end hit determination data D2 to the end position corresponding angle setting section 96. (Steps 410, 411). Subsequently, the plurality of acquired restriction position determination angles θi are discarded (step 412).

On the other hand, if the second dispersion ratio Rd2 is larger than the dispersion threshold Rth5 (step 405: NO) and if the temporary angle restriction component Iga_t is 50% or more of the rated current Ir (step 409: YES), the processes in steps 406 to 411 are not executed, and the process proceeds to step 412 to discard the plurality of acquired restriction position determination angles θi.

(End position corresponding angle setting section 96)
As shown in FIG. 4, the end position corresponding angle setting section 96 includes steering torque Th, absolute steering angle θs, q-axis current value Iq, angular velocity change amount Δωm, first regulation determination signal Sr1, end hit determination data D1, D2 and update permission signal Sp are input. The end position corresponding angle setting unit 96 sets the end position corresponding angles θs_le and θs_re in the memory 64 based on these state quantities.

The end position corresponding angle setting unit 96 sets the end position corresponding angles θs_le and θs_re when the end position corresponding angles θs_le and θs_re are not set in the memory 64 or when the update permission signal Sp is input. The end position corresponding angle setting unit 96 acquires a plurality of restriction position determination angles θi corresponding to the absolute steering angle θs in the calculation cycle in which the first restriction determination signal Sr1 indicating that the movement of the rack shaft 12 is restricted is input. do. The end position corresponding angle setting unit 96 of the present embodiment performs rigidity compensation for the absolute steering angle θs when it is determined that the movement of the rack shaft 12 is restricted, similarly to the dispersion determination unit 94, and performs rigidity compensation. The latter angle is obtained as the regulation position determination angle θi. In other words, the end position corresponding angle setting section 96 corresponds to an axial force detection section. The end position corresponding angle setting unit 96 determines whether the direction in which movement of the rack shaft 12 is restricted is to the left or to the right, based on the sign of the absolute steering angle θs. When the end position corresponding angle setting unit 96 acquires the left and right restriction position determination angles θi, it sets the end position corresponding angles θs_le and θs_re based on these.

Specifically, the end position corresponding angle setting unit 96 first calculates the stroke width Wma, which is the sum of the absolute value of the left restriction position determination angle θi and the absolute value of the right restriction position determination angle θi. Then, when the stroke width Wma is larger than the first stroke threshold value Wth1 and smaller than the second stroke threshold value Wth2, the end position corresponding angle setting unit 96 directly sets the acquired left and right regulation position determination angle θi to the end position. Set the corresponding angles θs_le and θs_re, respectively. Note that the first stroke threshold value Wth1 is an angular range indicated by the absolute steering angle θs, and is set to a slightly smaller range than the angular range corresponding to the entire stroke range of the rack shaft 12. Further, the second stroke threshold value Wth2 is an angular range indicated by the absolute steering angle θs, and is set to a slightly larger range than the angular range corresponding to the entire stroke range of the rack shaft 12.

By the way, for example, depending on the vehicle driving situation, end positioning only on the left or right side may repeatedly occur without setting the end position corresponding angles θs_le and θs_re on both the left and right sides, and the regulation position determination angle θi of either one may occur. It is assumed that there may be cases where it is not possible to obtain the In this case, the end position corresponding angle setting unit 96 first sets only the left end position corresponding angle θs_le or the right end position corresponding angle θs_re based on the end hit determination data D1 output from the dispersion determining unit 94. The end position corresponding angle setting unit 96 of this embodiment sets the average value of the end hit determination data D1 as the left end position corresponding angle θs_le or the right end position corresponding angle θs_re. Subsequently, the end position corresponding angle setting unit 96 acquires the left and right regulation position determination angles θi as described above, and sets the end position corresponding angles θs_le and θs_re.

Furthermore, for example, by replacing the steering shaft 11 when repairing a vehicle, it is assumed that the actual rack end angle at which end contact actually occurs and the stored end position corresponding angles θs_le and θs_re may deviate. In this case, the end position corresponding angle setting unit 96 first sets only the left end position corresponding angle θs_le or the right end position corresponding angle θs_re based on the end hit determination data D2 output from the update permission unit 95. The end position corresponding angle setting unit 96 of this embodiment sets the average value of the end hit determination data D2 as the end position corresponding angles θs_le and θs_re. Subsequently, the end position corresponding angle setting unit 96 acquires the left and right regulation position determination angles θi as described above, and sets the end position corresponding angles θs_le and θs_re.

Specifically, as shown in the flowchart of FIG. 10, upon acquiring various state quantities (step 501), the end position corresponding angle setting unit 96 determines whether an update permission signal Sp indicating permission for updating has been input. (Step 502). If the update permission signal Sp is not input (step 502: NO), it is determined whether a completion flag indicating that the end position corresponding angles θs_le and θs_re are set in the memory 64 is set (step 502: NO). Step 503). If the completion flag is set (step 503: YES), subsequent processing is not executed.

When the end position corresponding angle setting unit 96 receives the update permission signal Sp (step 502: YES), it resets the completion flag (step 504), and sets the end position corresponding angle in the calculation cycle in which the first regulation determination signal Sr1 is input. If there is, the restriction position determination angle θi is obtained (step 505). Note that even if the completion flag is not set (step 503: NO), the process proceeds to step 505 to obtain the restriction position determination angle θi.

Subsequently, the end position corresponding angle setting unit 96 determines whether the restriction position determination angles θi on both the left and right sides have been acquired (step 506), and if the restriction position determination angles θi on both the left and right sides have been acquired. (Step 506: YES), the stroke width Wma is calculated (Step 507). Next, it is determined whether the stroke width Wma is larger than the first stroke threshold value Wth1 and smaller than the second stroke threshold value Wth2 (step 508). If the stroke width Wma is larger than the first stroke threshold value Wth1 and smaller than the second stroke threshold value Wth2 (step 508: YES), the regulation position determination angle θi on both the left and right sides is the basis for calculating the stroke width Wma. are set as end position corresponding angles θs_le and θs_re (step 509), and a completion flag is set (step 510). Note that if the stroke width Wma is less than or equal to the first stroke threshold value Wth1, or if the stroke width Wma is greater than or equal to the second stroke threshold value Wth2 (step 508: NO), the obtained regulation position determination angle θi is discarded (step 511). ).

On the other hand, if the end position corresponding angle setting unit 96 has acquired only the left or right regulation position determination angle θi (step 506: NO), the end position corresponding angle setting unit 96 determines whether either the end hit determination data D1 or D2 has been input. It is determined whether or not (step 512). Then, when either of the end hit determination data D1, D2 is input (step 512: YES), the end position corresponding angle θs_le on the left side or the right side Only the end position corresponding angle θs_re is set (step 513). Note that if neither of the end hit determination data D1 or D2 has been input (step 512: NO), subsequent processing is not executed.

Next, the functions and effects of this embodiment will be explained.
(1) When the end position corresponding angle management unit 65 obtains the left and right regulation position determination angles θi, it compares the stroke width Wma with the first stroke threshold Wth1 and the second stroke threshold Wth2. . When the stroke width Wma is larger than the first stroke threshold Wth1 and smaller than the second stroke threshold Wth2, the end position corresponding angle management unit 65 controls the left and right angles based on the left and right regulation position determination angles θi. Set the right end position corresponding angles θs_le and θs_re, respectively. Therefore, it is possible to quickly set the left and right end position correspondence angles θs_le and θs_re that accurately correspond to the actual rack end angle, without having to wait until a plurality of left or right regulation position determination angles θi are obtained.

On the other hand, when the end position corresponding angle management unit 65 acquires a plurality of restriction position determination angles θi for only the left side or the right side, the end position corresponding angle management unit 65 calculates the restriction position determination angles θi based on the variance of the plurality of restriction position determination angles θi. It is determined whether the data is the data when the movement of the rack shaft 12 is restricted by the end abutment. Then, the end position corresponding angle management unit 65 generates end hit determination data D1 consisting of a plurality of left or right side restriction position determination angles θi that are determined to be data when the movement of the rack shaft 12 is regulated by the end hit. Based on this, the left end position corresponding angle θs_le or the right end position corresponding angle θs_re is set.

Here, if the variance of the multiple restriction position determination angles θi is large as described above, it is considered that the movement of the rack shaft 12 is restricted by hitting a curb, etc., and the variance of the multiple restriction position determination angles θi If is small, it is considered that the movement of the rack shaft 12 is restricted by the end abutment. Therefore, by using the distribution of a plurality of restriction position determination angles θi as in the present embodiment, it is possible to set end position corresponding angles θs_le and θs_re that accurately correspond to the actual end angles.

(2) The dispersion determination unit 94 calculates the first determination dispersion value Vd1 of the plurality of restriction position determination angles θi using the above equation (1). Then, when the first dispersion ratio Rd1, which is the ratio between the first dispersion value Vd1 and the predetermined dispersion value Vm, is equal to or less than the dispersion threshold Rthn set according to the number of acquisitions n, the plurality of regulation position judgment angles θi It is determined that the data is acquired when the movement of the rack shaft 12 is restricted by the end abutment. Therefore, it is possible to suitably determine whether or not the plurality of restriction position determination angles θi are data acquired when the movement of the rack shaft 12 is restricted by end contact. In particular, in order to calculate the first determination dispersion value Vd1 when two or more restriction position determination angles θi are acquired, the dispersion determination unit 94 of this embodiment acquires, for example, a predetermined number nca of restriction position determination angles θi. The first judgment variance value Vd1 can be calculated earlier than when calculating the first judgment variance value Vd1 from .

(3) The first restriction determination unit 92 and the second restriction determination unit 93 determine whether movement of the rack shaft 12 to the left or right is restricted based on the motor angular velocity ωm, the angular velocity change amount Δωm, and the steering torque Th. It is determined whether or not each of them is true. Therefore, it is possible to easily determine whether or not the movement of the rack shaft 12 is restricted, for example, without providing a dedicated sensor for detecting the movement of the rack shaft 12.

(4) The end position corresponding angle setting unit 96 sets the average value of the end hit determination data D1 and D2 as the left end position corresponding angle θs_le or the right end position corresponding angle θs_re, so it corresponds accurately to the actual end angle. The end position corresponding angles θs_le and θs_re can be suitably set.

(5) As mentioned above, when the variance of the multiple restriction position determination angles θi is large, the movement of the rack shaft 12 is restricted at the virtual end position by executing the end contact relaxation control, and the multiple restriction position determination angles θi are If the variance is small, it is considered that the movement of the rack shaft 12 cannot be restricted by executing the end contact relaxation control, and the movement of the rack shaft 12 is restricted by the end contact. In this regard, the end position corresponding angle management unit 65 allows updating of the end position corresponding angles θs_le, θs_re based on the distribution of the plurality of regulation position determination angles θi, and updates the end position corresponding angles θs_le, θs_re stored in the memory 64. Update. Therefore, even if the actual rack end angle and the stored end position corresponding angles θs_le and θs_re deviate due to, for example, replacing the steering shaft 11 when repairing the vehicle, according to this embodiment, the stored end position corresponding angles θs_le and θs_re The deviation of the end position corresponding angles θs_le and θs_re from the actual rack end angle toward the steering neutral position can be reduced.

(6) The update permission unit 95 calculates the second determination variance value Vd2 of the plurality of restriction position determination angles θi using the above equation (2). Then, when the second dispersion ratio Rd2, which is the ratio between the second judgment dispersion value Vd2 and the predetermined dispersion value Vm, is less than or equal to the dispersion threshold Rth5, the plurality of regulation position judgment angles θi are determined to prevent the movement of the rack shaft 12 due to the end contact. It is determined that the data was acquired when it was regulated. Therefore, it is possible to suitably determine whether or not the plurality of restriction position determination angles θi are data acquired when the movement of the rack shaft 12 is restricted by end contact.

(7) The update permission unit 95 associates the pinion shaft torque Tp when the movement of the rack shaft 12 is determined to be restricted by the second restriction determination unit 93 with the restriction position determination angle θi, and also associates the pinion shaft torque Tp with the restriction position determination angle θi. The regulation position determination angle θi is classified into the first to third axial force ranges set based on the magnitude of . The plurality of restriction position determination angles θi that are the basis for calculating the second determination variance value Vd2 include one or more restriction position determination angles θi classified into each of the first to third axial force ranges. In this way, the update permission unit 95 uses, as data used for dispersion determination, a plurality of restriction position determination angles θi classified into different axial force ranges, that is, restriction position determination angles θi obtained when the pinion shaft torque Tp is high. , and the regulation position determination angle θi obtained when the pinion shaft torque Tp is low.

Normally, when the vehicle is moving forward, the pinion shaft torque Tp when end contact occurs tends to be high, and when the vehicle is moving backward, the pinion shaft torque Tp when end contact occurs tends to be low. Therefore, in this embodiment, the data used to determine the dispersion includes the restriction position determination angle θi when it is determined that the movement of the rack shaft 12 is restricted during each forward and backward movement of the vehicle. Thereby, it is possible to more appropriately determine whether the movement of the rack shaft 12 is restricted by the end abutment.

(8) The update permission unit 95 calculates a temporary end position determination angle θe_t based on a plurality of restriction position determination angles θi that are determined to be data when the movement of the rack shaft 12 is restricted by end abutting, and A temporary end separation angle Δθ_t indicating the distance of the temporary end position determination angle θe_t from the end position corresponding angles θs_le and θs_re is calculated. Then, the update permission unit 95 calculates a provisional angle restriction component Iga_t according to the provisional end separation angle Δθ_t, and if the provisional angle restriction component Iga_t is 50% or more of the rated current Ir, the q-axis current command value Iq* is considered to be limited to a current threshold value Ith or less, and updating of the end position corresponding angles θs_le and θs_re is not permitted.

Here, even if the stored end position corresponding angles θs_le and θs_re do not deviate toward the steering neutral position with respect to the actual rack end angle, for example, when steering at high speed on a low μ road, the rack shaft 12 There may be a situation where the rack housing 13 comes into contact with the rack housing 13. Even in such a case, if the q-axis current command value Iq* is limited to the current threshold value Ith or less, the end contact relaxation control based on the stored end position corresponding angles θs_le and θs_re is functioning normally, and the end position The deviation of the corresponding angles θs_le and θs_re from the actual rack end angle toward the steering neutral position is not considered to be a problem. Therefore, when the q-axis current command value Iq* calculated based on the temporary end separation angle Δθ_t is equal to or less than the current threshold value Ith as in this embodiment, updating of the end position corresponding angles θs_le and θs_re is not permitted. , it is possible to suppress updating these when unnecessary.

(Second embodiment)
Next, a second embodiment of the steering control device will be described according to the drawings. Note that the main difference between this embodiment and the first embodiment described above is only the calculation of the second determination variance value Vd2 by the update permission section 95. Therefore, for convenience of explanation, the same components as in the first embodiment are given the same reference numerals, and the explanation thereof will be omitted.

Upon acquiring the left regulation position determination angle θi, the update permission unit 95 of the present embodiment sorts and holds the left side restriction position determination angle θi in descending order of pinion shaft torque Tp. When the update permitting unit 95 obtains a predetermined number nth of regulation position determination angles θi, the update permission unit 95 determines the regulation positions of a predetermined calculated number nca in descending order of the pinion shaft torque Tp, that is, the axial force acting on the rack shaft 12. The determination angles θi are selected, and the second determination variance value Vd2 of the selected regulation position determination angles θi is calculated using the above equation (2). Thereafter, the update permission section 95 calculates the second dispersion ratio Rd2 as in the first embodiment, and outputs the update permission signal Sp and the end hit determination data D2 to the end position corresponding angle setting section 96. In this embodiment, the predetermined acquisition number nth is "10" and the predetermined calculation number nca is "5".

Specifically, as shown in the flowchart of FIG. 11, upon acquiring various state quantities (step 601), the update permission unit 95 sets the regulation position determination angle θi to the pinion shaft linked to the regulation position determination angle θi. The torques Tp are sorted and held in ascending order (step 602). Subsequently, it is determined whether or not the number n of obtained restriction position determination angles θi is equal to or greater than a predetermined number nth (step 603). If the number n of acquired regulation position determination angles θi is less than the predetermined number nth of acquisitions (step 603: NO), subsequent processing is not executed.

On the other hand, if the number n of obtained regulation position determination angles θi is greater than or equal to the predetermined number nth of regulation position determination angles (step 603: YES), the update permission unit 95 regulates the predetermined calculation number nca in order from the smaller pinion shaft torque Tp. The position determination angle θi is selected, and the second determination variance value Vd2 of the selected regulation position determination angle θi is calculated using the above equation (2), and the second variance ratio Rd2 is calculated (step 604). Thereafter, as in the first embodiment, the process moves to step 405 where the second dispersion ratio Rd2 and the dispersion threshold Rth5 are compared in magnitude, and steps 406 to 412 are executed according to the result of the magnitude comparison.

As described above, in this embodiment, in addition to the operations and effects similar to those of (1) to (6) and (8) of the first embodiment, the following operations and effects are achieved.
(9) The update permission unit 95 associates the pinion shaft torque Tp when the second restriction determination unit 93 determines that the movement of the rack shaft 12 is restricted with the restriction position determination angle θi. The plurality of restriction position determination angles θi that are the basis for calculating the second determination variance value Vd2 include a predetermined number nca of restriction position determination angles θi selected in order from the one with the smallest pinion shaft torque Tp.

Here, if the end separation angle Δθ is less than the predetermined angle θ1, the q-axis current command value Iq* is limited so that the end separation angle Δθ is restricted from decreasing by executing the end contact relaxation control. The smaller the pinion shaft torque Tp is, the larger the regulation position determination angle θi associated with the pinion shaft torque Tp tends to be. That is, the smaller the pinion shaft torque Tp is, the more likely it is that the regulation position determination angle θi associated with the pinion shaft torque Tp is an angle close to the actual rack end angle. Therefore, by calculating the second judgment variance value Vd2 based on the regulation position judgment angle θi of the predetermined calculation number nca selected in order from the smaller pinion shaft torque Tp as in the present embodiment, the rack shaft 1 It is possible to more appropriately determine whether or not the movement of is restricted.

Each of the above embodiments can be modified and implemented as follows. The above embodiments and the following modified examples can be implemented in combination with each other within a technically consistent range.
- In each of the above embodiments, when the left and right regulation position determination angles θi were obtained, the stroke width Wma was compared in magnitude with the first stroke threshold value Wth1 and the second stroke threshold value Wth2. However, the present invention is not limited to this. Only the magnitude comparison between the stroke width Wma and the first stroke threshold value Wth1 is performed, and when the stroke width Wma is larger than the first stroke threshold value Wth1, based on the left and right regulation position determination angles θi. Then, the left and right end position corresponding angles θs_le and θs_re may be set, respectively.

- In each of the above embodiments, the average value of the end hit determination data D1 and D2 is set as the left end position corresponding angle θs_le or the right end position corresponding angle θs_re. However, the present invention is not limited to this, and for example, the regulation position determination angle θi having the largest absolute value among the end hit determination data D1 and D2 may be set as the left end position corresponding angle θs_le or the right end position corresponding angle θs_re. . Even with this configuration, the end position corresponding angles θs_le and θs_re that accurately correspond to the actual end angles can be suitably set.

- In each of the above embodiments, even if the end position corresponding angle setting unit 96 obtains the left and right regulation position determination angles θi, the end position corresponding angle setting unit 96 determines the position of the rack shaft 12 by end contact based on the distribution of the plurality of regulation position determination angles θi. It is also possible to determine whether or not the data is for when movement is restricted, and to set the left and right end position corresponding angles θs_le and θs_re.

- In each of the embodiments described above, as the method for calculating the first determined dispersion value Vd1 by the dispersion determining section 94, the method for calculating the second determined dispersion value Vd2 in consideration of the pinion shaft torque Tp by the update permission section 95 may be used. Similarly, as a method for calculating the second determined variance value Vd2 by the update permission unit 95, the first determined variance value Vd1 that does not take into account the pinion shaft torque Tp determined by the variance determining unit 94 may be used.

- In each of the embodiments described above, the first restriction determination unit 92 may be configured to perform only one of the static restriction determination and the dynamic restriction determination. Further, the second restriction determination unit 93 may be configured to perform both static restriction determination and dynamic restriction determination, or only dynamic restriction determination. Note that if the determination performed by the first restriction determination section 92 and the determination performed by the second restriction determination section 93 match, the end position corresponding angle management section 65 may include only one of the restriction determination sections. Needless to say, it's a good thing.

- In each of the above embodiments, the first restriction determination unit 92 determines whether the movement of the rack shaft 12 to the left or right is restricted based on the motor angular velocity ωm, the angular velocity change amount Δωm, and the steering torque Th. However, the determination method is not limited to this, and the determination method can be changed as appropriate. For example, a contact sensor may be provided between the rack end 18 and the rack housing 13, and it may be determined based on the output signal from the contact sensor whether movement of the rack shaft 12 to the left or right is restricted. good. Similarly, the determination method of the second regulation determination section 93 can be changed as appropriate.

- In each of the above embodiments, the update permission unit 95 calculates the average value of the plurality of restriction position determination angles θi as the provisional end position determination angle θe_t. , the regulation position determination angle θi having the largest or smallest absolute angle may be set as the provisional end position determination angle θe_t.

- In the first embodiment, the regulation position determination angle θi is classified into the first to third axial force ranges based on the pinion shaft torque Tp, but the present invention is not limited to this. It may be classified into axial force ranges.

- In the first embodiment described above, there is one regulation position judgment angle θi classified into each of the first to third axial force ranges among the plurality of regulation position judgment angles θi that are the basis for calculating the second judgment variance value Vd2. Although included above, the present invention is not limited to this, as long as one or more regulation position determination angles θi classified into at least two or more of the first to third axial force ranges are included.

- In each of the above embodiments, the current threshold value Ith is set to 50% of the rated current Ir, but it is not limited to this, and may be set to 40% or 60%, for example, and the value can be changed as appropriate.
- In each of the above embodiments, when the temporary angle limiting component Iga_t is 50% or more of the rated current Ir, it is determined that the q-axis current command value Iq* is less than or equal to the current threshold value Ith. A temporary q-axis current command value may be calculated assuming that the end separation angle Δθ is the temporary end separation angle Δθ_t, and a comparison may be made with the current threshold value Ith.

- In each of the above embodiments, when the second dispersion ratio Rd2 is equal to or less than the dispersion threshold Rth5 and the plurality of regulation position determination angles θi are determined to be data obtained when the movement of the rack shaft 12 is regulated by end contact. In this case, the end position corresponding angles θs_le and θs_re may be updated regardless of whether the q-axis current command value Iq* is limited to the current threshold value Ith or less.

- In each of the above embodiments, once the end position corresponding angles θs_le and θs_re are set, the necessity of updating them may not be determined and the update may not be permitted.
- In each of the above embodiments, the pinion shaft torque Tp is calculated based on the steering torque Th, the motor torque, and the inertia torque. The pinion shaft torque Tp may be calculated based on this. In addition, the pinion shaft torque Tp is used in the stiffness compensation performed for the absolute steering angle θs obtained as a result of the dynamic restriction judgment, and the pinion shaft torque Tp is used in the stiffness compensation performed for the absolute steering angle θs obtained as a result of the static restriction judgment. The pinion shaft torque Tp may be different.

- In each of the above embodiments, the absolute steering angle θs when the dispersion determination unit 94, update permission unit 95, and end position corresponding angle setting unit 96 determine that the movement of the rack shaft 12 is restricted is directly used as the restriction position determination angle. It is also possible to obtain it as θi without performing stiffness compensation.

- In each of the above embodiments, the pinion shaft torque Tp is used as the axial force at the time of determination, but the pinion shaft torque Tp is not limited to this, and other state quantities that approximate the axial force acting on the rack shaft 12 may be used.
- In the second embodiment described above, in step 603, the acquired left side restriction position determination angles θi are sorted and held in descending order of pinion shaft torque Tp, but the present invention is not limited to this, and the acquired left side restriction position determination angles θi may be simply held without sorting them in descending order of pinion shaft torque Tp. In this case, in step 604, the control position judgment angles θi of the predetermined number nca of calculations are selected from among the control position judgment angles θi of the predetermined number nth obtained, in order from the one with the smallest pinion shaft torque Tp.

- In the second embodiment, the predetermined acquisition number nth is set larger than the predetermined calculation number nca, but the predetermined acquisition number nth is not limited to this, and can be changed as appropriate as long as it is greater than or equal to the predetermined calculation number nca. Further, the predetermined number of calculations nca can be changed as appropriate.

- In each of the above embodiments, by monitoring whether or not the motor 21 rotates even when the ignition switch is off, the number of rotations of the motor 21 from the origin is constantly integrated, and the absolute motor angle and absolute steering angle θs are detected. However, the present invention is not limited to this. For example, a steering sensor that detects the steering angle as an absolute angle is provided, and the rotation speed of the motor 21 from the origin is determined based on the steering angle detected by the steering sensor and the reduction ratio of the reduction mechanism 22. The motor absolute angle and the absolute steering angle θs may be detected by integrating the values.

- In each of the above embodiments, the end hit relaxation control is executed by limiting the assist command value Ias* to the steering angle limit value Ien, but the present invention is not limited to this. For example, the rack end position The end contact mitigation control may be executed by adding a steering reaction force component that increases as the value approaches the assist command value Ias*, that is, a component whose sign is opposite to the assist command value Ias*.

- In each of the above embodiments, the assist command value Ias* is subjected to guard processing, but the present invention is not limited to this. For example, the assist command value Ias* may be corrected by a compensation amount based on a torque differential value obtained by differentiating the steering torque Th. Guard processing may be performed on the value.

- In each of the above embodiments, the limit value setting unit 62 includes the voltage limit value calculation unit 72 that calculates the voltage limit value Ivb based on the power supply voltage Vb, but the voltage limit value calculation unit 72 is not limited to this. In addition or in place of it, another calculation unit that calculates another limit value based on another state quantity may be provided. Alternatively, the limit value setting section 62 may not include the voltage limit value calculation section 72 and may directly set the steering angle limit value Ien as the limit value Ig.

- In each of the above embodiments, the steering angle limit value Ien may be a value obtained by subtracting only the angle limit component Iga from the rated current Ir.
- In each of the above embodiments, the steering control device 1 controls the EPS 2 in which the EPS actuator 6 applies motor torque to the column shaft 15; The control target may be a steering device that applies motor torque to the motor 12. In addition to the EPS, the steering control device 1 controls a steer-by-wire type steering device in which power transmission is separated between a steering section operated by a driver and a steering section that steers steered wheels. For the torque command value or the q-axis current command value of the motor of the steering actuator provided in the steering section, the end contact relaxation control may be performed as in this embodiment.

DESCRIPTION OF SYMBOLS 1... Steering control device, 2... Electric power steering device (EPS), 3... Steering wheel, 4... Steering wheel, 5... Steering mechanism, 6... EPS actuator, 11... Steering shaft, 12... Rack shaft, 13... Rack housing , 18... Rack end, 21... Motor, 41... Microcomputer, 42... Drive circuit, 51... Current command value calculation section, 52... Motor control signal generation section, 53... Absolute steering angle detection section, 61... Assist command value calculation section , 62...Limit value setting section, 63...Guard processing section, 64...Memory, 65...End position corresponding angle management section, 91...Angular velocity change amount calculation section, 92...First regulation determination section, 93...Second regulation determination section , 94...Dispersion determination unit, 95...Update permission unit, 96...End position corresponding angle setting unit, D1, D2...End hit determination data, Id*...d-axis current command value, Iq*...q-axis current command value, Ig ...Limit value, Ir...Rated current, Ith...Current threshold, nca...Predetermined number of calculations, nth...Predetermined number of obtained pieces, Rd1...First dispersion ratio, Rd2...Second dispersion ratio, Rth2, Rth3, Rth4, Rth5, Rthn... Dispersion threshold, Sm...Motor control signal, Sp...Update permission signal, Sr1...First regulation judgment signal, Sr2...Second regulation judgment signal, Vd1...First judgment variance value, Vd2...Second judgment variance value, Vm...Default Variance value, Wma...Stroke width, Wth1...First stroke threshold, Wth2...Second stroke threshold, Th...Steering torque, Tm...Motor torque, Tp...Pinion shaft torque, θs...Absolute steering angle, θi...Restriction position determination angle , θm...rotation angle, θs_le, θs_re...end position corresponding angle, θe_t...temporary end position determination angle, Δθ...end separation angle, Δθ_t...temporary end separation angle, ωm...motor angular velocity, Δωm...angular velocity variation.

Claims (6)

A steering device comprising a housing, a steered shaft reciprocably housed in the housing, and an actuator that uses a motor as a drive source to apply a motor torque to reciprocate the steered shaft,
An absolute steering angle detection unit that detects an absolute steering angle, which is a rotation angle of a rotating shaft that can be converted into a steering angle of a steered wheel connected to the steered shaft, and is expressed as an absolute angle that includes a range exceeding 360°. and,
a restriction determination unit that determines whether movement of the steering shaft to either the left or right side is restricted;
Obtaining a plurality of restriction position determination angles corresponding to the absolute steering angle when the movement of the steering shaft is determined to be restricted, and based on the variance of the plurality of restriction position determination angles on the left side or the right side, a dispersion determination unit that determines whether the plurality of left or right restriction position determination angles is data when movement of the steered shaft is restricted due to contact of the steered shaft with the housing;
Based on the plurality of restriction position determination angles that are determined to be data when the movement of the steered shaft is regulated by the end abutment where the steered shaft contacts the housing, the steered shaft is on the left side or A steering control device comprising: an end position corresponding angle setting unit that sets an end position corresponding angle that is an angle indicating that the steering wheel is at the right end position and is associated with the absolute steering angle. The steering control device according to claim 1,
The dispersion determination unit calculates the determination dispersion value Vd, which is the dispersion value of n (where n is an integer of 2 or more) left or right regulation position determination angles θi (where i is a natural number), using the following formula:
(However, θave is the average value of n regulation position judgment angles θi)
Calculate using
A value preset as a variance value of a plurality of restriction position determination angles on the left side or right side when movement of the steering shaft is restricted by the end stop is set as a default variance value Vm,
When the dispersion ratio Rd obtained by dividing the determination dispersion value Vd by the predetermined dispersion value Vm is equal to or less than the dispersion threshold Rthn set according to n, the n regulation position determination angles are determined by the end application. A steering control device that determines that the data is acquired when movement of the steered shaft is regulated. The steering control device according to claim 1 or 2,
The end position corresponding angle setting section is
When setting the end position corresponding angle, the restriction position determination on the left side and the right side is determined to be data when the movement of the steered shaft is regulated by the end abutment where the steered shaft contacts the housing. When each angle is acquired, a stroke width that is the sum of the absolute value of the left regulation position determination angle and the absolute value of the right regulation position determination angle corresponds to the entire stroke range of the steered shaft. Comparing the stroke width with a stroke threshold, if the stroke width is larger than the stroke threshold, setting the left and right end position corresponding angles based on the left and right regulation position determination angles, respectively;
When setting the end position corresponding angle, the restriction position only on the left or right side is determined to be data when the movement of the steered shaft is regulated by the end abutment where the steered shaft contacts the housing. When a plurality of determination angles are obtained, the left side is determined based on the plurality of restriction position determination angles on the left side or right side that are determined to be data when the movement of the steered shaft is restricted by the end stop. Or a steering control device that sets the angle corresponding to the end position on the right side. The steering control device according to any one of claims 1 to 3,
The restriction determination unit is configured to restrict movement of the steered shaft to either the left or the right based on the angular velocity of the motor, the amount of change in angular velocity that is the amount of change in the angular velocity, and the steering torque input to the steering device. A steering control device that determines whether the The steering control device according to any one of claims 1 to 4,
The end position corresponding angle setting unit sets an average value of a plurality of restriction position determination angles on the left side or right side that are determined to be data when movement of the steered shaft is restricted by the end stopper to the left side or right side. A steering control device that sets an angle corresponding to the end position on the right side. The steering control device according to any one of claims 1 to 4,
The end position corresponding angle setting section selects the most absolute value of the plurality of restriction position determination angles on the left side or right side that are determined to be data when movement of the steered shaft is restricted by the end stop. A steering control device that sets the large restriction position determination angle as the left or right end position corresponding angle.