JP7147473B2 - steering controller - 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) is known as a steering system for a vehicle, in which an assist mechanism having a motor as a drive source provides an assist force for assisting a steering operation to a steering mechanism. Some of the steering control devices that use the EPS as a control target calculate an assist command value so that a larger assist force is applied to the steering mechanism based on an increase in the steering torque input to the steering mechanism (for example, , Patent Document 1).

By the way, in the EPS, the road surface reaction force, which is the force that the steered wheels receive from the road surface, is transmitted to the steering wheel via the steering mechanism. Then, the driver can grasp the road surface information such as the friction coefficient (μ) of the road surface and unevenness from the magnitude and change of the road surface reaction force transmitted to the steering wheel. In this way, the road surface reaction force can convey road surface information to the driver, but for example, vibrations that are unnecessary for grasping the road surface reaction force are also transmitted to the steering wheel, which may lead to a decrease in steering feeling. There is

Therefore, for example, in Patent Document 2, a first assist component based on the steering torque and a second assist component based on the execution of angle feedback control that causes the rotation angle of the rotating shaft that can be converted to the turning angle of the steered wheels to follow the target rotation angle. A steering control device that calculates an assist command value based on an assist component is disclosed. By applying the assist force including such a second assist component to the steering mechanism, the actual turning angle follows the target turning angle. It can be suppressed and the steering feeling can be improved.

Further, the steering control device uses a model (steering model) that represents the relationship between the torque and the rotation angle of a rotating shaft that rotates with the rotation of the steering wheel in calculating the target rotation angle. The steering control device uses an axial force sensor to detect an axial force acting on the steered shaft as a force that resists the steering operation according to the reaction force of the road surface. The input torque is calculated based on , and the rotation angle when the input torque is input to the model is calculated as the target rotation angle. As a result, the target rotation angle, that is, the second assist component changes due to the change in the axial force according to the road surface condition. Therefore, by adding the axial force to the calculation of the input torque as in Patent Document 2, it is possible to improve the steering feeling while conveying road surface information to the driver through changes in the second assist component (assist command value). can.

Japanese Unexamined Patent Application Publication No. 2011-111080 JP-A-2014-943

However, in the configuration of Patent Document 2, for example, when an abnormality occurs in the axial force sensor, the axial force does not accurately reflect the road surface reaction force, and the assist command value calculated using the axial force. is also an abnormal value. Therefore, there is a possibility that the road surface reaction force transmitted to the steering wheel cannot be adjusted appropriately through changes in the assist command value.

This problem is not limited to the configuration in which the assist command value is calculated using the second assist component based on the execution of the angle feedback control, and similarly occurs when the axial force is used as the basis for calculating the assist command value. obtain. In addition, not only when the axial force is detected by the axial force sensor, but also in the case of estimating the axial force based on various state quantities acquired by the steering control device, when an abnormality occurs in these various state quantities. can have similar problems.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a steering control device capable of preventing improper adjustment of the road surface reaction force transmitted to the steering wheel.

A steering control device for solving the above-mentioned problems controls a steering device that applies an assist force for assisting a steering operation to a steering mechanism by an assist mechanism using a motor as a drive source, and a first assist component based on the steering torque. and a basic reaction force including at least one of a plurality of types of axial forces acting on a steered shaft to which steerable wheels are connected and a tire force acting on the steerable wheels. and a target rotation angle calculation unit for calculating a target rotation angle of a rotation shaft that can be converted into a turning angle of a steerable wheel, using a reaction force component based on the basic reaction force. and a second assist component calculation unit that calculates a second assist component by executing angle feedback control based on the rotation angle and the target rotation angle, and an assist command value based on the first assist component and the second assist component. The basic reaction force calculation unit controls the operation of the motor so as to generate an assist force according to Then, the basic reaction force is calculated so that the contribution rate of the abnormal force to the basic reaction force is lower than when any one of the plurality of types of axial force and tire force is normal.

A steering control device for solving the above-mentioned problems controls a steering device that applies an assist force for assisting a steering operation to a steering mechanism by an assist mechanism using a motor as a drive source, and a steering torque to be input to the steering mechanism. a torque command value calculation unit that calculates a torque command value that is a target value of the steering torque and the torque command value; a first assist component calculation unit that calculates a first assist component by executing torque feedback control based on the steering torque and the torque command value; a basic reaction force calculation unit that calculates a basic reaction force including at least one of a plurality of axial forces acting on a steered shaft to which a steering wheel is connected and a tire force acting on the steered wheels; a target rotation angle calculation unit that calculates a target rotation angle of a rotation angle of a rotary shaft that can be converted into a turning angle of a steerable wheel, using the reaction force component and the first assist component; a second assist component calculation unit that calculates a second assist component by executing angle feedback control based on the target rotation angle, and the motor generates an assist force corresponding to an assist command value based on the second assist component; and the basic reaction force calculation unit, if any of the acquired plurality of types of axial force and the tire force is abnormal, the plurality of types of axial force and the tire The basic reaction force is calculated so that the contribution rate of the abnormal force to the basic reaction force is lower than when any of the forces is not abnormal.

A steering control device for solving the above-mentioned problems controls a steering device that applies an assist force for assisting a steering operation to a steering mechanism by an assist mechanism using a motor as a drive source, and a steered shaft to which steerable wheels are connected. Using a basic reaction force calculation unit that calculates a basic reaction force including at least one of a plurality of types of axial forces acting on the steered wheels and a tire force acting on the steered wheels, and a reaction force component based on the basic reaction force, A torque command value calculation unit that calculates a torque command value that is a target value of the steering torque to be input to the steering mechanism; and an assist command that calculates an assist command value by executing torque feedback control based on the steering torque and the torque command value. and a value calculation unit for controlling operation of the motor so as to generate an assist force corresponding to the assist command value, wherein the basic reaction force calculation unit calculates the acquired axial forces and When any one of the tire forces is abnormal, the contribution rate of the abnormal force to the basic reaction force becomes lower than when any one of the plurality of types of axial force and the tire force is not abnormal. to calculate the basic reaction force.

According to each of the above configurations, the assist command value changes according to changes in the basic reaction force (reaction force component) according to the road surface condition. In the above configuration, when either the axial force or the tire force is abnormal, the influence (contribution) of the abnormal axial force or tire force to the value of the basic reaction force is small, so the assist command value (assist force) can be suppressed from becoming an abnormal value. Therefore, even if the road surface reaction force transmitted to the steering wheel is adjusted by changing the assist command value, it is possible to prevent the adjustment from becoming inappropriate.

In the steering control device described above, the basic reaction force calculation unit determines, when any one of the acquired axial forces and tire forces is abnormal, that the contribution rate of the abnormal force to the basic reaction force is It is preferable to calculate the basic reaction force to be zero.

According to the above configuration, since the influence of the abnormal axial force or tire force on the value of the basic reaction force is eliminated, it is possible to suitably suppress the assist command value from becoming an abnormal value. Therefore, inappropriate adjustment of the road reaction force transmitted to the steering wheel can be suitably suppressed.

In the steering control device described above, the basic reaction force calculation unit calculates one of the plurality of types of axial force and tire force when any one of the plurality of types of axial force and tire force acquired is abnormal. It is preferable to calculate the basic reaction force so that the contribution rate of forces other than the abnormal force to the basic reaction force is higher than when is not abnormal.

According to the above configuration, it is possible to suppress a change in the magnitude of the assist command value before and after an abnormality occurs in any one of a plurality of types of axial force and tire force, thereby reducing the driver's sense of discomfort.

According to the present invention, inappropriate adjustment of the road reaction force transmitted to the steering wheel can be suppressed.

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. FIG. 2 is a block diagram of a reaction force component calculator according to the first embodiment; The block diagram of the reaction force component calculating part of 2nd Embodiment. The block diagram of the assist command value calculating part of 3rd Embodiment. The block diagram of the steering control apparatus of 4th 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 system (EPS) 1 as a steering system to be controlled includes a steering mechanism 4 that turns steerable wheels 3 based on the operation of a steering wheel 2 by a driver. . The EPS 1 also includes an assist mechanism 5 that applies an assist force for assisting the steering operation to the steering mechanism 4 and a steering control device 6 that controls the operation of the assist mechanism 5 .

The steering mechanism 4 includes a steering shaft 11 to which the steering wheel 2 is fixed, a rack shaft 12 as a steering shaft connected to the steering shaft 11, and a cylindrical rack housing through which the rack shaft 12 is reciprocally inserted. 13 and a rack and pinion mechanism 14 that converts the rotation of the steering shaft 11 into the reciprocating motion of 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 2 is located.

The rack shaft 12 and the pinion shaft 17 are arranged in the rack housing 13 with a predetermined crossing angle. The rack-and-pinion mechanism 14 is configured by engaging rack teeth 12 a formed on the rack shaft 12 and pinion teeth 17 a formed on the pinion shaft 17 . Further, tie rods 19 are rotatably connected to both ends of the rack shaft 12 through rack ends 18 formed of ball joints provided at the ends of the shaft. The tip of the tie rod 19 is connected to a knuckle (not shown) to which the steered wheels 3 are assembled. Therefore, in the EPS 1, rotation of the steering shaft 11 accompanying steering operation is converted into axial movement of the rack shaft 12 by the rack and pinion mechanism 14, and this axial movement is transmitted to the knuckles via the tie rods 19. The steered angle of the steered wheels 3, that is, the traveling direction of the vehicle is changed.

The assist mechanism 5 includes a motor 21 that is a driving source, a transmission mechanism 22 that transmits the rotation of the motor 21, and a conversion mechanism 23 that converts the rotation transmitted through the transmission mechanism 22 into reciprocating motion of the rack shaft 12. I have. The assist mechanism 5 transmits the rotation of the motor 21 to the conversion mechanism 23 via the transmission mechanism 22, and converts the rotation into the reciprocating motion of the rack shaft 12 by the conversion mechanism 23, thereby applying an assist force to the steering mechanism 4. . The motor 21 of this embodiment employs, for example, a three-phase brushless motor, the transmission mechanism 22 employs, for example, a belt mechanism, and the conversion mechanism 23 employs, for example, a ball screw mechanism.

A torque sensor 41 is connected to the steering control device 6 to detect the steering torque Th applied to the steering shaft 11 by steering by the driver. The steering control device 6 is also connected to a left front wheel sensor 42l and a right front wheel sensor 42r provided in a hub unit 42 that rotatably supports the steered wheels 3 via a drive shaft (not shown). A left front wheel sensor 42l and a right front wheel sensor 42r detect the wheel speeds Vl and Vr of the steered wheels 3, respectively. The steering control device 6 of this embodiment detects the average value of the wheel speeds Vl and Vr as the vehicle speed V. FIG. Further, the steering control device 6 is connected with a rotation sensor 43 for detecting the motor angle .theta.m of the motor 21 as a relative angle within the range of 360.degree. The steering torque Th and the motor angle θm are detected as positive values when steering in one direction (right in this embodiment) and as negative values when steering in the other direction (left in this embodiment). do. The steering control device 6 is also connected to an axial force sensor 45 that acquires a sensor axial force Fse, which is a detected value of the axial force acting on the rack shaft 12 . As the axial force sensor 45, for example, one that detects the axial force based on the pressure change according to the stroke of the rack shaft 12 can be used. The steering control device 6 acquires the sensor axial force Fse in terms of torque (N·m). The steering control device 6 supplies driving power to the motor 21 based on the state quantities input from these sensors, thereby operating the assist mechanism 5, that is, causing the steering mechanism 4 to reciprocate the rack shaft 12. Control the assist force to be applied.

Next, the configuration of the steering control device 6 will be described.
As shown in FIG. 2, the steering control device 6 includes a microcomputer 51 that outputs a motor control signal Sm, and a drive circuit 52 that supplies drive power to the motor 21 based on the motor control signal Sm. A well-known PWM inverter having a plurality of switching elements (for example, FETs, etc.) is employed in the drive circuit 52 of the present embodiment. A motor control signal Sm output from the microcomputer 51 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. output to Each control block shown below is implemented by a computer program executed by the microcomputer 51, detects each state quantity at a predetermined sampling cycle (detection cycle), and Each arithmetic processing shown in the control block is executed.

The microcomputer 51 receives the vehicle speed V, the steering torque Th, the motor angle .theta.m, and the sensor axial force Fse. Further, the microcomputer 51 receives the phase current values Iu, Iv, and Iw of the motor 21 detected by the current sensors 55 provided in the connection lines 54 between the drive circuit 52 and the motor coils of the respective phases. . In addition, in FIG. 2, for convenience of explanation, the connection lines 54 of each phase and the current sensors 55 of each phase are collectively illustrated as one. Then, the microcomputer 51 outputs a motor control signal Sm based on these state quantities.

Specifically, the microcomputer 51 includes an assist command value calculator 61 that calculates the assist command value Ta* and a motor control signal calculator 63 that calculates the motor control signal Sm.
As will be described later, the assist command value calculation unit 61 calculates a first assist component Ta1 based on the steering torque Th and a second assist component Ta2 based on execution of angle feedback control for causing the pinion angle θp to follow the target pinion angle θp*. , an assist command value Ta* corresponding to the assist force to be applied by the steering mechanism 4 is calculated.

The motor control signal calculator 63 calculates target current values Id* and Iq*, which are target values of the drive current to be supplied to the motor 21, based on the assist command value Ta*. Target current values Id* and Iq* indicate the target current value on the d-axis and the target current value on the q-axis in the d/q coordinate system, respectively. The motor control signal calculator 63 calculates the q-axis target current value Iq* having a larger absolute value as the absolute value of the assist command value Ta* increases. Note that the d-axis target current value Id* is basically zero. Then, the motor control signal calculator 63 executes current feedback control in the d/q coordinate system based on the target current values Id*, Iq*, the phase current values Iu, Iv, Iw, and the motor angle θm of the motor 21. to generate a control signal.

Specifically, the motor control signal calculator 63 maps the phase current values Iu, Iv, and Iw onto the d/q coordinates based on the motor angle θm, thereby obtaining the actual current of the motor 21 in the d/q coordinate system. d-axis current value Id and q-axis current value Iq are calculated. Then, the motor control signal calculator 63 adjusts the d-axis and A target voltage value is calculated based on each current deviation on the q-axis, and a motor control signal Sm having a duty ratio based on the target voltage value is calculated. Note that the q-axis current value Iq calculated in the process of generating the motor control signal Sm is output to the assist command value calculator 61 .

The motor control signal Sm calculated in this manner is output to the drive circuit 52 . As a result, the motor 21 is supplied with drive power from the drive circuit 52 in accordance with the motor control signal Sm. Then, the motor 21 applies an assist force indicated by the assist command value Ta* to the steering mechanism 4 .

Next, the configuration of the assist command value calculator 61 will be described.
The steering torque Th, vehicle speed V, motor angle θm, sensor axial force Fse, and q-axis current value Iq are input to the assist command value calculator 61 . The assist command value calculator 61 calculates an assist command value Ta* based on these state quantities.

Specifically, the assist command value calculator 61 includes a first assist component calculator 71 that calculates the first assist component Ta1, a reaction force component calculator 72 that calculates the reaction force component Fir, and a target pinion angle θp*. and a pinion angle calculator 74 for calculating the pinion angle θp. Further, the assist command value calculation unit 61 is an angle feedback control unit (hereinafter referred to as angle F/B control) that calculates the second assist component Ta2 by executing angle feedback control that causes the actual pinion angle θp to follow the target pinion angle θp*. part) 75. Then, the assist command value calculation section 61 calculates the assist command value Ta* based on the first assist component Ta1 and the second assist component Ta2.

More specifically, the steering torque Th and the vehicle speed V are input to the first assist component computing section 71 . The first assist component computing section 71 computes a first assist component Ta1, which is a force for assisting the steering operation, based on these state quantities. Specifically, the first assist component computing section 71 computes the first assist component Ta1 having a larger absolute value as the absolute value of the steering torque Th increases and as the vehicle speed V decreases. The first assist component Ta1 calculated in this manner is output to the target pinion angle calculator 73 and the adder .

The steering torque Th, the vehicle speed V, the sensor axial force Fse, and the target pinion angle θp* are input to the reaction force component calculation unit 72 . As will be described later, the reaction force component calculation unit 72 calculates a reaction force component Fir, which is a force that resists the steering operation, based on these state quantities, and outputs the reaction force component Fir to the target pinion angle calculation unit 73 .

The steering torque Th, the vehicle speed V, the first assist component Ta1, and the reaction force component Fir are input to the target pinion angle calculator 73 . The target pinion angle calculation unit 73 calculates a target pinion angle θp* as a target rotation angle of the pinion shaft 17, which is a rotation shaft that can be converted into a turning angle of the steerable wheels 3, based on these state quantities. Specifically, the target pinion angle calculator 73 associates the input torque Tin*, which is a value obtained by adding the steering torque Th to the first assist component Ta1 and subtracting the reaction force component Fir, to the target pinion angle θp*. A target pinion angle θp* is calculated using a model (steering model) formula.

Tin*=C..theta.p*'+J..theta.hp'' (1)
This model formula defines and expresses the relationship between the torque and the rotation angle of the rotating shaft that rotates as the steering wheel 2 rotates. This model formula is expressed using a viscosity coefficient C that models the friction of the EPS 1 and an inertia coefficient J that models the inertia of the EPS 1 . Note that the viscosity coefficient C and the inertia coefficient J are variably set according to the vehicle speed V. FIG. The target pinion angle θp* thus calculated is output to the subtractor 77 and the reaction force component calculator 72 .

A motor angle θm is input to the pinion angle calculator 74 . A pinion angle calculator 74 calculates a pinion angle θp indicating the rotation angle (steering angle) of the pinion shaft 17 based on the motor angle θm. Specifically, the pinion angle calculator 74 integrates (counts) the number of revolutions of the motor 21 with the pinion angle θp as the origin (zero degrees) when the rack shaft 12 is in a neutral position where the vehicle travels straight, for example. Based on the rotational speed and the motor angle .theta.m, the pinion angle .theta.p is calculated as an absolute angle including a range exceeding 360.degree. The pinion angle θp calculated in this manner is output to the subtractor 77 .

An angle deviation Δθ obtained by subtracting the pinion angle θp from the target pinion angle θp* in the subtractor 77 is input to the angle F/B control unit 75 . Based on the angle deviation Δθ, the angle F/B control unit 75 calculates a second assist component Ta2, which is a force that assists the steering operation, as a control amount for feedback-controlling the pinion angle θp to the target pinion angle θp*. Specifically, the second assist component Ta2 calculates the sum of the output values of the proportional element, the integral element and the differential element to which the angular deviation .DELTA..theta. The second assist component Ta2 calculated in this manner is output to the adder 76. FIG.

The adder 76 of the assist command value calculator 61 calculates a value obtained by adding the second assist component Ta2 to the first assist component Ta1 as an assist command value Ta*, and outputs the result to the motor control signal calculator 63 .

Next, the configuration of the reaction force component calculator 72 will be described.
The vehicle speed V, the sensor axial force Fse, the q-axis current value Iq, and the target pinion angle θp* are input to the reaction force component calculator 72 . The reaction force component calculator 72 calculates a reaction force component Fir corresponding to the axial force acting on the rack shaft 12 based on these state quantities, and outputs the calculated reaction force component Fir to the target pinion angle calculator 73 .

As shown in FIG. 3, the reaction force component calculation unit 72 includes an abnormality determination unit 81 that determines whether each state quantity (signal) to be input is abnormal, and a reaction force component Fir based on each state quantity. and a basic reaction force calculator 82 for calculating the basic reaction force.

The vehicle speed V, the sensor axial force Fse, the q-axis current value Iq, and the target pinion angle θp* are input to the abnormality determination unit 81 . The abnormality determination unit 81 determines that there is an abnormality when, for example, each state quantity becomes an unacceptable value, or when the amount of change from the previous value exceeds a preset threshold value. It is determined whether each state quantity is abnormal. Then, the abnormality determination unit 81 uses the input vehicle speed V, the sensor axial force Fse, the q-axis current value Iq, and the target pinion angle θp* as they are, together with the determination signal Sde indicating the determination result of the abnormality determination, to the basic reaction force calculation unit 82 . output to

The basic reaction force calculator 82 includes a current axial force calculator 83 that calculates a current axial force (road surface axial force) Fer and an angular axial force calculator 84 that calculates an angular axial force (ideal axial force) Fib. there is The current axial force Fer and the angular axial force Fib are calculated in terms of torque (N·m). Further, the basic reaction force calculation unit 82 calculates current axial force Fer, angular axial force Fib, and sensor axial force so that the axial force applied to the steered wheels 3 from the road surface (road surface information transmitted from the road surface) is reflected. A distributed axial force calculation unit 85 is provided for calculating a distributed axial force obtained by distributing the force Fse at a predetermined ratio as a reaction force component Fir (basic reaction force).

A q-axis current value Iq is input to the current axial force calculator 83 . The current axial force calculation unit 83 converts the current axial force Fer, which is an estimated value of the axial force acting on the steered wheels 3 (transmission force transmitted to the steered wheels 3) reflecting the road surface information, into the q-axis current value Iq Calculate based on Specifically, the current axial force calculation unit 83 calculates that the torque applied to the rack shaft 12 from the motor 21 and the steering torque Th are balanced with the torque corresponding to the force applied to the steered wheels 3 from the road surface. The calculation is performed so that the absolute value of the current shaft force Fer increases as the absolute value of the shaft current value Iq increases. The current axial force Fer calculated in this manner is output to the distributed axial force calculation unit 85 .

The target pinion angle θp* and the vehicle speed V are input to the angular axial force calculator 84 . The angular axial force calculator 84 converts the angular axial force Fib, which is an ideal value of the axial force acting on the steered wheels 3 (transmission force transmitted to the steered wheels 3) and does not reflect the road surface information, into the target pinion angle θp*. calculated based on Specifically, the angular axial force calculation unit 84 calculates so that the absolute value of the angular axial force Fib increases as the absolute value of the target pinion angle θp* increases. Further, the angular axial force calculation unit 84 calculates so that the absolute value of the angular axial force Fib increases as the vehicle speed V increases. The angular axial force Fib calculated in this manner is output to the distributed axial force calculation unit 85 .

In addition to the determination signal Sde, the current axial force Fer and the angular axial force Fib, the sensor axial force Fse is input to the distributed axial force calculation unit 85 . The distribution axial force calculator 85 includes a current distribution gain Ger indicating the distribution ratio of the current axial force Fer, an angle distribution gain Gib indicating the distribution ratio of the angular axial force Fib, and a sensor distribution gain indicating the distribution ratio of the sensor axial force Fse. Gse is preset by experiment or the like. The current distribution gain Ger, the angle distribution gain Gib, and the sensor distribution gain Gse are variably set according to the vehicle speed V. FIG. Then, the distributed axial force calculator 85 multiplies the angular axial force Fib by the angular distribution gain Gib, the current axial force Fer by the current distribution gain Ger, and the sensor axial force Fse by the sensor distribution gain Gse. The reaction force component Fir is calculated by adding the values obtained. That is, the basic reaction force calculator 82 of the present embodiment acquires three axial forces, ie, the current axial force Fer, the angular axial force Fib, and the sensor axial force Fse, and based on these three axial forces, the reaction force component Fir ( basic reaction force).

In the steering control device 6 configured as described above, the target pinion angle θp* is calculated by adding the reaction force component Fir (axial force) to the input torque Tin*, and the pinion angle θp follows the target pinion angle θp*. The assist command value Ta* includes the second assist component Ta2 for causing the acceleration to occur. Therefore, the road surface reaction force transmitted to the steering wheel 2 can be adjusted through changes in the second assist component Ta2 (assist command value Ta*) according to road surface conditions, and vibrations and the like can be suppressed while conveying road surface information to the driver. As a result, it is possible to improve the steering feeling. However, if an abnormality occurs in the axial force sensor 45, for example, the reaction force component Fir based on the sensor axial force Fse and, by extension, the assist command value Ta* may become an abnormal value.

In this regard, in the present embodiment, each of the distributed gains Ger, Gib, and Gse is set to a different value according to the determination result indicated by the determination signal Sde. Specifically, when there is an abnormality in the acquired state quantity, the distribution gain multiplied by the axial force based on the state quantity with the abnormality becomes smaller than when there is no abnormality, and each state quantity without abnormality It is set so that the distribution gain multiplied by the axial force based on is large. That is, the basic reaction force calculation unit 82 of the present embodiment determines that the axial force is abnormal when the state quantity for calculating the axial force is abnormal. Then, each of the distribution gains Ger, Gib, and Gse, when there is an abnormality in each acquired state quantity, the contribution ratio of the axial force (abnormal axial force) based on the state quantity with the abnormality to the reaction force component Fir is It is set so that the rate of contribution of the axial force (normal axial force) based on each normal state quantity to the reaction force component Fir increases as the value decreases.

As an example, the current distribution gain Ger is "0.3" when each state quantity is normal, "0" when the q-axis current value Iq is abnormal, and other than the q-axis current value Iq (target pinion If at least one of the angle θp*, the vehicle speed V, and the sensor axial force Fse) is abnormal, it is set to "0.45". The angle distribution gain Gib is "0.45" when each state quantity is normal, "0" when at least one of the target pinion angle θp* and the vehicle speed V is abnormal, and the target pinion angle θp * and the vehicle speed V (at least one of the q-axis current value Iq and the sensor axial force Fse) is abnormal, it is set to "0.6". Further, the sensor distribution gain Gse is "0.7" when each state quantity is normal, "0" when the sensor axial force Fse is abnormal, and other than the sensor axial force Fse (target pinion angle θp* , and at least one of the vehicle speed V and the q-axis current value Iq) is set to "0.9". The values of the distribution gains Ger, Gib, and Gse can be appropriately changed, and the sum of these may be set to "1", or may be set to be larger or smaller than "1". good.

Next, the operation and effects of this embodiment will be described.
(1) If any of the current axial force Fer, the angular axial force Fib, and the sensor axial force Fse is abnormal, the basic reaction force calculator 82 calculates distribution gains Ger and Gib by which the abnormal axial force is multiplied. , Gse are set to zero, the contribution ratio of the abnormal axial force to the reaction force component Fir (basic reaction force) is set to zero. Specifically, when there is no abnormality in the current axial force Fer, the angular axial force Fib, and the sensor axial force Fse, the basic reaction force calculation unit 82 sets the current axial force Fer to 30% and the angular axial force Fib to 45%. , the sensor axial force Fse is distributed at a rate of 70% to calculate the reaction force component Fir. Here, for example, assuming a case where the value of the sensor axial force Fse is abnormal, the basic reaction force calculation unit 82 sets the current axial force Fer to 45%, the angular axial force Fib to 60%, and the sensor axial force Fse to 0%. , and calculate the reaction force component Fir. This eliminates the influence (contribution) of the abnormal axial force on the value of the reaction force component Fir, so that it is possible to suitably suppress the assist command value Ta* from becoming an abnormal value. Therefore, even if the road surface reaction force transmitted to the steering wheel 2 is adjusted by changing the assist command value Ta*, it is possible to suitably prevent the adjustment from becoming inappropriate.

(2) When any one of the current axial force Fer, the angular axial force Fib, and the sensor axial force Fse is abnormal, the basic reaction force calculation unit 82 multiplies the axial force other than the abnormal axial force. By increasing Ger, Gib, and Gse, the contribution rate of the axial force other than the abnormal axial force to the reaction force component Fir is increased. As a result, it is possible to suppress the change in the magnitude of the steering reaction force before and after an abnormality occurs in any of the current axial force Fer, the angular axial force Fib, and the sensor axial force Fse, thereby reducing the discomfort felt by the driver. can.

(Second embodiment)
Next, a second embodiment of the steering control device will be described with reference to the drawings. For convenience of explanation, the same components as those of the first embodiment are denoted by the same reference numerals, and the explanation thereof is omitted.

As shown in FIG. 4, the target pinion angle θp*, vehicle speed V, q-axis current value Iq, and tire force Ft are input to the reaction force component calculator 72 of the present embodiment, but the sensor axial force Fse is not input. The tire force Ft is the load in the longitudinal direction of the vehicle (x direction), the load in the lateral direction of the vehicle (y direction), the load in the vertical direction of the vehicle (z direction), the load detected by the hub unit 42 (see FIG. 1), and the load in the vertical direction of the vehicle (z direction). It is a value (unit: Newton) based on at least one of the moment about the axis, the moment about the y-axis, and the moment about the z-axis.

The vehicle speed V, the q-axis current value Iq, the target pinion angle θp*, and the tire force Ft are input to the abnormality determination unit 81 of the present embodiment. Then, the abnormality determination unit 81 performs abnormality determination of each state quantity in the same manner as in the first embodiment, and together with the determination signal Sde indicating the determination result, the input vehicle speed V, q-axis current value Iq, and target pinion angle θp* and the tire force Ft are directly output to the basic reaction force calculator 82 .

The basic reaction force calculation unit 82 of this embodiment includes a torque conversion unit 91 and an output switching unit 92 in addition to the current axial force calculation unit 83 , the angular axial force calculation unit 84 and the distribution axial force calculation unit 85 . The current axial force calculation unit 83 and the angular axial force calculation unit 84 calculate the current axial force Fer and the angular axial force Fib, respectively, and output them to the distribution axial force calculation unit 85 in the same manner as in the first embodiment.

The distributed axial force calculation unit 85 includes a distribution gain calculation unit 101 that calculates a current distribution gain Ger and an angle distribution gain Gib based on the vehicle speed V. FIG. The distribution gain calculator 101 of this embodiment has a map that defines the relationship between the vehicle speed V and the distribution gains Ger and Gib. do. The current distribution gain Ger has a larger value when the vehicle speed V is high than when it is low, and the angle distribution gain Gib has a smaller value when the vehicle speed V is high than when it is low. In this embodiment, the values are set so that the sum of the distributed gains Ger and Gib is "1". The current distribution gain Ger calculated in this way is output to the multiplier 102, and the angle distribution gain Gib is output to the multiplier 103. FIG.

The current axial force Fer is input to the multiplier 102 and the angular axial force Fib is input to the multiplier 103 . In the distributed axial force calculation unit 85, the multiplier 102 multiplies the current axial force Fer by the current distribution gain Ger, the multiplier 103 multiplies the angular axial force Fib by the angular distribution gain Gib, and the adder 104 multiplies the angular axial force Fib by the angular distribution gain Gib. are added together to calculate the distributed axial force Fd. The distributed axial force Fd calculated in this manner is output to the output switching section 92 .

A tire force Ft is input to the torque conversion unit 91 . The torque conversion unit 91 calculates the tire torque Tt around the pinion shaft 17 by multiplying the tire force Ft by a conversion coefficient Kp based on the rotational speed ratio of the rack-and-pinion mechanism 14 . The tire torque Tt calculated in this manner is output to the output switching section 92 .

The determination signal Sde is input to the output switching unit 92 in addition to the distributed axial force Fd and the tire torque Tt. Based on the determination signal Sde, the output switching unit 92 outputs the distributed axial force Fd as the reaction force component Fir when there is no abnormality in each state quantity that is the basis of the distributed axial force Fd. If at least one is abnormal, the tire torque Tt is output as the reaction force component Fir. That is, the basic reaction force calculator 82 of the present embodiment obtains three forces, the current axial force Fer and the angular axial force Fib, and the tire force Ft, and distributes the distribution axis based on the current axial force Fer and the angular axial force Fib. The force Fd or the tire torque Tt based on the tire force Ft is output as the reaction force component Fir. Further, the basic reaction force calculation unit 82 reduces the contribution ratio of the abnormal axial force to the reaction force component Fir by switching to the tire torque Tt when there is an abnormality in each state quantity that is the basis of the distributed axial force Fd. (zero) to calculate the reaction force component Fir.

As described above, the present embodiment has the same action and effect as the action and effect of (1) of the first embodiment.
(Third embodiment)
Next, a third embodiment of the steering control device will be described with reference to the drawings. For convenience of explanation, the same components as those of the first embodiment are denoted by the same reference numerals, and the explanation thereof is omitted.

As shown in FIG. 5, the first assist component computing section 71 of the present embodiment computes the first assist component Ta1 by executing the torque command value computing section 111 that computes the torque command value Th1* and the torque feedback computation. and a torque feedback control section (hereinafter referred to as a torque F/B control section) 112 .

Specifically, the drive torque Tc obtained by adding the first assist component Ta1 to the steering torque Th in the adder 113 is input to the torque command value calculation unit 111 . Based on the drive torque Tc, the torque command value calculator 111 calculates a torque command value Th1*, which is a target value of the steering torque Th to be input by the driver with respect to the drive torque Tc. Specifically, the torque command value calculation unit 111 calculates the torque command value Th1*, which has a larger absolute value as the absolute value of the drive torque Tc increases.

Torque F/B control unit 112 receives torque deviation ΔT1 obtained by subtracting torque command value Th1* from steering torque Th in subtractor 114 . Based on the torque deviation ΔT1, the torque F/B control unit 112 calculates the first assist component Ta1 as a control amount for feedback-controlling the steering torque Th to the torque command value Th1*. Specifically, the torque F/B control unit 112 calculates the sum of the output values of the proportional element, the integral element, and the differential element to which the torque deviation ΔT1 is input, as the first assist component Ta1.

The first assist component Ta1 calculated in this manner is output to the target pinion angle calculator 73 and the adder 76, as well as to the adder 113, as in the first embodiment. As a result, the target pinion angle θp* is calculated in the target pinion angle calculator 73 in the same manner as in the first embodiment. The adder 76 adds the first assist component Ta1 and the second assist component Ta2 to calculate the assist command value Ta*.

Then, as in the first embodiment, if there is an abnormality in the state quantity, the reaction force component calculation unit 72 calculates The reaction force component Fir is calculated so that the contribution rate becomes low.

As described above, the present embodiment has the same actions and effects as the actions and effects (1) and (2) of the first embodiment.
(Fourth embodiment)
Next, a fourth embodiment of the steering control device will be described with reference to the drawings. For convenience of explanation, the same components as those of the first embodiment are denoted by the same reference numerals, and the explanation thereof is omitted.

As shown in FIG. 6, the assist command value calculator 61 of the present embodiment includes a reaction force component calculator 72, a pinion angle calculator 74, a torque command value calculator 121, and a torque F/B controller 122. , the first assist component calculator 71 and the target pinion angle calculator 73 are not provided. The pinion angle calculator 74 calculates the pinion angle θp as in the first embodiment.

The vehicle speed V, the sensor axial force Fse, the q-axis current value Iq, and the pinion angle θp are input to the reaction force component calculator 72 . That is, instead of the target pinion angle θp*, the pinion angle θp is input to the reaction force component calculation unit 72 of the present embodiment. The reaction force component calculation unit 72 is the same as in the first embodiment except that the angular axial force calculation unit 84 calculates the angular axial force Fib based on the pinion angle θp instead of the target pinion angle θp*. Calculate the reaction force component Fir.

The torque command value calculation unit 121 calculates the torque command value Th2*, which has a larger absolute value as the absolute value of the reaction force component Fir increases. The torque deviation ΔT2 obtained by subtracting the torque command value Th2* from the steering torque Th in the subtractor 123 is input to the torque F/B control unit 122 . Based on the torque deviation ΔT2, the torque F/B control unit 122 calculates an assist command value Ta* as a control amount for feedback-controlling the steering torque Th to the torque command value Th2*. Specifically, the torque F/B control unit 122 calculates the sum of the output values of the proportional element, the integral element, and the differential element to which the torque deviation ΔT2 is input, as the assist command value Ta*.

Then, as in the first embodiment, if there is an abnormality in the state quantity, the reaction force component calculation unit 72 calculates The reaction force component Fir is calculated so that the contribution rate becomes low.

As described above, the present embodiment has the same actions and effects as the actions and effects (1) and (2) of the first embodiment.
This embodiment can be implemented with the following modifications. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.

In the third embodiment, the assist command value Ta* is calculated by adding the first assist component Ta1 and the second assist component Ta2. It may be calculated as a value Ta*.

・In the first, third, and fourth embodiments, the reaction force component Fir is calculated based on the current axial force Fer, the angular axial force Fib, and the sensor axial force Fse. Additionally or alternatively, the reaction force component Fir may be calculated using an axial force estimated based on other state quantities. Such other axial force includes, for example, vehicle state quantity axial force calculated based on yaw rate and lateral acceleration, tire axial force calculated based on tire force Ft, and the like. Similarly, in the above-described second embodiment, the distributed axial force Fd may be calculated using other state quantities.

- In the above-described second embodiment, the distributed axial force Fd or the tire torque Tt is output as the reaction force component Fir according to the result of the abnormality determination. However, the configuration for switching the output according to the determination result is not limited to this. Either one may be output, and the other may be output when the state quantity that is the basis of the one is abnormal.

- In the first, third, and fourth embodiments, if any of the current axial force Fer, the angular axial force Fib, and the sensor axial force Fse is abnormal, the distribution gain Ger is multiplied by the abnormal axial force. , Gib, and Gse are set to zero, but the distribution gains Ger, Gib, and Gse may be set to values greater than zero as long as they are smaller than the normal case. As a result, the effect of the abnormal axial force on the value of the reaction force component Fir is reduced, so that the assist command value Ta* can be prevented from becoming an abnormal value.

・In the first, third, and fourth embodiments, if any of the current axial force Fer, the angular axial force Fib, and the sensor axial force Fse is abnormal, the axial force other than the abnormal axial force is multiplied. Although the distribution gains Ger, Gib and Gse to be applied are increased, the present invention is not limited to this.

In each of the above-described embodiments, the abnormality determination unit 81 determines abnormality of the value of each state quantity itself, and determines that the axial force is abnormal when there is abnormality in the state quantity for calculating the axial force. However, not limited to this, in addition to or instead of the same determination, for example, an abnormality in the arithmetic processing (for example, the arithmetic processing of the current axial force calculation unit 83 that calculates the current axial force Fer based on the q-axis current value Iq) is judged. However, whether or not the axial force is abnormal may be determined based on the same determination result, and the method for determining abnormality can be changed as appropriate.

- In each of the above embodiments, the current axial force Fer is calculated based on the q-axis current value Iq, but is not limited to this, and may be calculated based on, for example, the q-axis target current value Iq*.
・In the first to third embodiments, the angular axial force Fib is calculated based on the target pinion angle θp* and the vehicle speed V. However, the calculation is not limited to this, and may be calculated based only on the target pinion angle θp*. . Similarly, in the fourth embodiment, the angular axial force Fib may be calculated based only on the pinion angle θp. Further, the angular axial force Fib may be calculated by other methods such as adding other parameters such as the steering torque Th and the vehicle speed V.

- In the above-described second embodiment, the distributed axial force calculation section 85 may calculate the distributed gains Ger and Gib in consideration of parameters other than the vehicle speed V. For example, in a vehicle in which a drive mode indicating the setting state of a control pattern of an in-vehicle engine or the like can be selected from among a plurality of drive modes, the drive mode may be used as a parameter for setting the distribution gains Ger and Gib. In this case, it is possible to employ a configuration in which the distributed axial force calculation unit 85 is provided with a plurality of maps showing different tendencies with respect to the vehicle speed V for each drive mode, and the distributed gains Ger and Gib are calculated by referring to the maps.

- In each of the above-described embodiments, the reaction force component calculation unit 72 may calculate the reaction force component Fir by adding a reaction force other than the distributed axial force Fd or the tire torque Tt. As such a reaction force, for example, when the absolute value of the steering angle of the steering wheel 2 approaches the steering angle threshold value, an end reaction force, which is a reaction force that resists further turning steering, can be employed. As the steering angle threshold, for example, a virtual rack end that is set on the neutral position side of the mechanical rack end position where the axial movement of the rack shaft 12 is restricted by the rack end 18 coming into contact with the rack housing 13 The pinion angle θp at position can be used.

In each of the above-described embodiments, the target pinion angle calculation unit 73 uses a model formula modeled by adding a so-called spring term using the spring coefficient K determined by the specifications of the suspension, wheel alignment, etc. to determine the target pinion angle. An angle θp* may be calculated.

In each of the above embodiments, the steering control device 6 controls the EPS 1 in which the assist mechanism 5 applies an assist force to the rack shaft 12 via the transmission mechanism 22 and the conversion mechanism 23. However, the steering control device 6 is not limited to this. For example, a steering device that applies motor torque to the column shaft 15 via a speed reduction mechanism may be controlled.

Next, technical ideas that can be grasped from the above embodiments and modifications will be added below.
(b) The steering control device, wherein the basic reaction force calculation unit calculates the distributed axial force or the tire force obtained by adding up the plurality of types of axial forces at an individually set distribution ratio as the basic reaction force.

DESCRIPTION OF SYMBOLS 1... Electric power steering apparatus (EPS), 2... Steering wheel, 3... Steering wheel, 4... Steering mechanism, 5... Assist mechanism, 6... Steering control apparatus, 11... Steering shaft, 12... Rack shaft (steering shaft) , 17... Pinion shaft (rotating shaft), 21... Motor, 51... Microcomputer, 61... Assist command value calculation unit, 71... First assist component calculation unit, 72... Reaction force component calculation unit, 73... Target pinion angle calculation unit (target rotation angle calculation unit), 74... pinion angle calculation unit, 75... angle F/B control unit (assist component calculation unit), 81... abnormality determination unit, 82... basic reaction force calculation unit, 83... current axial force calculation Part 84... Angle axial force calculation part 85... Distribution axial force calculation part 91... Torque conversion part 92... Output switching part 101... Distribution gain calculation part 111, 121... Torque command value calculation part 112, 122 …Torque F/B control unit Fd …Distributed axial force Ft …Tire force Fer …Current axial force Fib …Angular axial force Fir …Reaction force component (basic reaction force) Fse …Sensor axial force Ger … Current distribution gain Gib Angle distribution gain Gse Sensor distribution gain Sde Judgment signal Ta* Assist command value Ta1 First assist component Ta2 Second assist component Th Steering torque Th* Torque command value, Tt... tire torque, ?p... pinion angle (rotation angle), ?p*... target pinion angle (target rotation angle).

Claims (5)

A steering device that applies an assist force for assisting a steering operation to a steering mechanism by an assist mechanism that uses a motor as a drive source is controlled,
a first assist component calculation unit that calculates a first assist component based on the steering torque;
a basic reaction force calculation unit that calculates a basic reaction force including at least one of a plurality of axial forces acting on a steered shaft to which steerable wheels are coupled and a tire force acting on the steerable wheels;
a target rotation angle calculation unit that calculates a target rotation angle, which is a target rotation angle of a rotation shaft that can be converted into a turning angle of a steered wheel, using a reaction force component based on the basic reaction force;
a second assist component calculation unit that calculates a second assist component by executing angle feedback control based on the rotation angle and the target rotation angle;
A steering control device that controls operation of the motor so as to generate an assist force corresponding to an assist command value based on the first assist component and the second assist component,
The basic reaction force calculation unit, when any one of the plurality of types of axial force and the tire force acquired is abnormal, is compared to a case where any of the plurality of types of axial force and the tire force is not abnormal. , a steering control device that calculates the basic reaction force so that the contribution rate of the abnormal force to the basic reaction force is low; A steering device that applies an assist force for assisting a steering operation to a steering mechanism by an assist mechanism that uses a motor as a drive source is controlled,
a torque command value calculation unit that calculates a torque command value that is a target value of the steering torque to be input to the steering mechanism;
a first assist component calculation unit that calculates a first assist component by executing torque feedback control based on the steering torque and the torque command value;
a basic reaction force calculation unit that calculates a basic reaction force including at least one of a plurality of axial forces acting on a steered shaft to which steerable wheels are coupled and a tire force acting on the steerable wheels;
a target rotation angle calculation unit that calculates a target rotation angle of a rotation shaft that can be converted into a turning angle of a steered wheel, using the reaction force component based on the basic reaction force and the first assist component; ,
a second assist component calculation unit that calculates a second assist component by executing angle feedback control based on the rotation angle and the target rotation angle;
A steering control device that controls operation of the motor so as to generate an assist force corresponding to an assist command value based on the second assist component,
The basic reaction force calculation unit, when any one of the plurality of types of axial force and the tire force acquired is abnormal, is compared to a case where any of the plurality of types of axial force and the tire force is not abnormal. , a steering control device that calculates the basic reaction force so that the contribution rate of the abnormal force to the basic reaction force is low; A steering device that applies an assist force for assisting a steering operation to a steering mechanism by an assist mechanism that uses a motor as a drive source is controlled,
a basic reaction force calculation unit that calculates a basic reaction force including at least one of a plurality of axial forces acting on a steered shaft to which steerable wheels are coupled and a tire force acting on the steerable wheels;
a torque command value calculation unit that calculates a torque command value, which is a target value of the steering torque to be input to the steering mechanism, using a reaction force component based on the basic reaction force;
an assist command value calculation unit that calculates an assist command value by executing torque feedback control based on the steering torque and the torque command value;
A steering control device that controls operation of the motor so as to generate an assist force corresponding to the assist command value,
The basic reaction force calculation unit, when any one of the plurality of types of axial force and the tire force acquired is abnormal, is compared to a case where any of the plurality of types of axial force and the tire force is not abnormal. , a steering control device that calculates the basic reaction force so that the contribution rate of the abnormal force to the basic reaction force is low; In the steering control device according to any one of claims 1 to 3,
The basic reaction force calculation unit, when any one of the acquired plural types of axial force and the tire force is abnormal, calculates the basic reaction force so that the contribution rate of the abnormal force to the basic reaction force becomes zero. A steering control device that calculates the basic reaction force. In the steering control device according to any one of claims 1 to 4,
The basic reaction force calculation unit, when any one of the plurality of types of axial force and the tire force acquired is abnormal, is compared to a case where any of the plurality of types of axial force and the tire force is not abnormal. 3. A steering control device for calculating the basic reaction force so as to increase the contribution ratio of forces other than the abnormal force to the basic reaction force.

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