JP2019131072A - Steering control device - Google Patents

Abstract

To provide a steering control device which allows a steering person to steer naturally, when steering wheels are deviated to a travel direction of a vehicle.SOLUTION: A control device 80 comprises a mid point learning function for learning a mid point of a detected steering angle. The control device 80 comprises a function as a reaction force control part for calculating steering reaction force by determining distribution of estimated axial force based on road face information and ideal axial force based on the target steering angle calculated based on the steering angle. The control device 80 as the reaction force control part, reduces distribution of the estimated axial force in the steering reaction force when the steering wheels 30 are deviated to a travel direction of the vehicle.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a steering control device.

  Since the steer-by-wire type steering control device has no mechanical connection between the steered wheel and the steering, a steering reaction force based on road surface information is applied to the steering by a reaction force actuator (Patent Document 1). Patent Document 2, Patent Document 3).

  In Patent Document 1, when the road surface reaction force acting on the left and right steered wheels is estimated, the reaction force actuator applies the steering reaction force to the steering based on the road surface reaction force, and there is an abnormality such as puncture The steering reaction force is fixed to the value at the time of the abnormality. As a result, the fluctuation of the steering reaction force accompanying the abnormality of the steered wheels is suppressed, and a good steering feeling is given to the steering wheel.

  In Patent Literature 2, when there is a midpoint shift of the detected turning angle, the steering control device performs midpoint learning (referred to as midpoint correction in Patent Literature 2). In the midpoint learning, for example, when the turning angle is zero and the turning angular velocity that is a time differential value of the turning angle is also zero, the output of the reaction force actuator is zero (that is, the steering reaction force). Is not zero), correction is performed so that the output of the reaction force actuator becomes zero, assuming that there is a midpoint shift.

  The reason for learning the midpoint is that the steered angle sensor outputs a signal having the same value when the steered wheel is positioned at the neutral position (position when the vehicle travels in the straight traveling direction) due to various causes. This is because there is no limit. For example, the output of the turning angle sensor may fluctuate due to the use of the vehicle over a long period of time.

  In addition, paying attention to the axial force acting on the steered shaft connected to the steered wheels, the ideal axial force calculated from the target steered angle obtained based on the steering angle of the steering and the estimate calculated from the road surface information For example, Patent Literature 3 discloses a steering reaction force that is determined based on the distribution of the axial force.

JP 2006-282203 A JP 2002-37108 A JP 2017-165219 A

  By the way, when performing the midpoint learning as in Patent Document 2 and determining the steering reaction force based on the distribution of the ideal axial force and the estimated axial force in Patent Document 3, when the vehicle can travel normally, the following is performed. Done.

  As shown in FIG. 8 (a), when the vehicle can travel normally, if the middle point is learned, when traveling in the straight direction, the middle point of the steered shaft 110 (hereinafter referred to as the steered shaft midpoint), The point where the steered wheel 100 faces the straight direction coincides.

  As described above, when the middle point learning is performed and the vehicle can travel normally, when the steering operation is performed to move the vehicle straight, the output of the reaction force actuator becomes zero because the steered wheel 100 faces the straight traveling direction, and the steering reaction force becomes zero. Is maintained at zero.

  In addition, when the vehicle is able to travel normally when the midpoint learning is performed, when the steering operation is performed to turn the vehicle, the output of the reaction force actuator is output because the steered wheel 100 faces in a direction deviating from the straight traveling direction. The steering reaction force based on the distribution of the ideal axial force and the estimated axial force is generated by making the distribution of the estimated axial force calculated from the road surface information larger than that before steering.

On the other hand, when the steered wheel 100 is punctured or the air pressure is lowered and the vehicle cannot normally travel, there are the following problems.
When the vehicle cannot normally travel, if the middle point learning is performed, as shown in FIG. 8B, when the vehicle travels in the straight traveling direction, the turning shaft midpoint and when the steered wheels 100 are directed in the straight traveling direction. The midpoint does not match.

  Therefore, when the vehicle cannot normally travel, in the case of Patent Document 3, the steered wheel 100 moves straight in the state of FIG. 8C, and the steered wheel 100 moves in the straight direction. Since the direction of the deviation is directed, the output of the reaction force actuator is desired to be zero, but a steering reaction force based on the estimated axial force calculated from the road surface information is generated. For this reason, the steering reaction force is not maintained when the vehicle goes straight.

  Further, when the vehicle cannot normally travel, in the case of Patent Document 3, the steered wheel 100 turns while the steered wheel 100 is in the state of FIG. Therefore, the output of the reaction force actuator should match the turning angle, but no steering reaction force based on the estimated axial force calculated from the road surface information is generated. For this reason, no steering reaction force is generated when the vehicle turns.

  An object of the present invention is to provide a steering control device that enables a steering person to steer naturally when traveling with the steered wheels deviating from the traveling direction of the vehicle.

  In order to solve the above problems, the steering control device of the present invention includes a midpoint learning unit that learns the midpoint of the detected turning angle, and a reaction force actuator that applies a steering reaction force that resists steering operation. A steering actuator that steers the steered wheel via a steered shaft under a power cutoff state between the steered wheel and the steering, and a steering actuator that controls the steered actuator according to the steering state of the steering. A reaction force actuator is provided to determine the distribution between the rudder control unit, the estimated axial force based on the road surface information, and the ideal axial force based on the target turning angle calculated based on the steering angle, and to apply the steering reaction force. A steer-by-wire steering device having a reaction force control unit that controls the steering control device, wherein the reaction force control unit is in a state in which the steered wheels are displaced with respect to the traveling direction of the vehicle. Where the vehicle runs It is intended to reduce the distribution of the estimated axial force in the steering reaction force.

  With the above configuration, the reaction force control unit reduces the distribution of the estimated axial force in the steering reaction force when the vehicle travels with the steered wheels deviating from the traveling direction of the vehicle. For this reason, when the steered wheels are punctured or the air pressure drops, etc., and the vehicle is traveling with the steered wheels deviating from the direction of travel of the vehicle, the steered shaft midpoint and the steered wheels are directed straight ahead Even when the midpoint learning is performed in a state where the midpoint does not coincide with the midpoint, the steering can naturally steer the steering.

  Further, the reaction force control unit has a value indicating that the lateral acceleration acting on the vehicle, the yaw rate, and the steering angle of the steering indicate a straight traveling direction, and the state where the steering reaction force is applied continues the straight traveling determination time. Preferably, the vehicle travels in a state where the steered wheels are deviated from the straight traveling direction that is the traveling direction of the vehicle.

  With the above-described configuration, it is possible to determine the case where the vehicle is traveling with the steered wheels deviating from the straight traveling direction that is the traveling direction of the vehicle. After this determination, the distribution of the estimated axial force in the reaction force can be reduced.

  Further, when the lateral acceleration acting on the vehicle, the yaw rate, and the steering angle of the steering are not values indicating a straight traveling direction, and the state where the steering reaction force is not applied continues the turning determination time. Alternatively, the vehicle may be traveling in a state where the steered wheels are deviated from the turning direction that is the traveling direction of the vehicle.

  With the above configuration, it can be determined that the vehicle is traveling so as to turn in a state where the steered wheels face the traveling direction of the vehicle. After this determination, the distribution of the estimated axial force in the reaction force can be reduced.

  In addition, when the vehicle travels in a state where the steered wheels are deviated from the traveling direction of the vehicle, the reaction force control unit is configured to reduce the distribution of the estimated axial force in the steering reaction force by decreasing gradually. Also good.

With the above configuration, when the vehicle travels with the steered wheels deviating from the traveling direction of the vehicle, the distribution of the estimated axial force in the steering reaction force can be gradually reduced and reduced.
Further, it is preferable that the reaction force control unit increases the distribution of the ideal axial force in the steering reaction force when the vehicle travels in a state where the steered wheels are deviated from the traveling direction of the vehicle.

  In the above configuration, when the vehicle travels with the steered wheels deviating from the traveling direction of the vehicle, the distribution of the estimated axial force in the steering reaction force is reduced by increasing the distribution of the ideal axial force in the steering reaction force. As a result, when the steered wheel is punctured or the air pressure drops, etc., and the vehicle is traveling with the steered wheel deviating from the traveling direction of the vehicle, the steered shaft midpoint and the steered wheel are directed straight ahead Even when the midpoint learning is performed in a state where the midpoint does not coincide with the midpoint, the steering can naturally steer the steering.

  ADVANTAGE OF THE INVENTION According to this invention, when driving | running | working a vehicle in the state from which the steered wheel shifted | deviated with respect to the advancing direction of a vehicle, there exists an effect which enables a steering person to steer naturally.

1 is an overall schematic diagram showing a steer-by-wire steering device to which a steering control device of an embodiment is applied. The block diagram of the steering control apparatus of the embodiment. The figure which shows the threshold value of the steering angle and turning angle concerning the embodiment. The block diagram which shows the axial force distribution calculating part concerning the embodiment. The flowchart of the midpoint process regarding a steering angle. The flowchart of the determination process which a determination part performs. The whole schematic diagram which shows the steer-by-wire type steering device to which the steering control device of other embodiments is applied. (A) is an explanatory diagram when the middle point of the turning angle and the middle point of the turning shaft coincide with each other when the steered wheel and the steered shaft are both directed straight in the normal state. When the vehicle is not able to travel normally due to puncture of the steered wheel or a drop in air pressure, etc., the center point of the steered shaft when the vehicle travels in the straight direction coincides with the midpoint when the steered wheel is directed straight Explanatory drawing of disappearance, (c) is applied to the steering and the direction of the axial force applied to the steered shaft when the vehicle travels in the straight direction when in the state of (b) Explanatory drawing of the direction of the steering reaction force, (d) is that the steering reaction force applied to the steering based on the estimated axial force does not occur when the vehicle travels in the turning direction in the state of (b). FIG.

(Embodiment)
Hereinafter, an embodiment of a steering control device will be described with reference to the drawings.
As shown in FIG. 1, in the steer-by-wire type steering device to which the steering control device according to the present embodiment is applied, the steering wheel (steering 10) applies a reaction force that is a force resisting the operation of the steering wheel 10. Connected to the reaction force actuator 20. The reaction force actuator 20 drives a steering shaft 22 fixed to the steering wheel 10, a reaction force side speed reducer 24, a reaction force motor 26 having a rotating shaft 26 a connected to the reaction force side speed reducer 24, and the reaction force motor 26. An inverter 28 is provided. Here, the reaction force motor 26 is a surface magnet synchronous motor (SPMSM).

  The reaction force motor 26 is connected to the battery 72 via the inverter 28. The inverter 28 is a circuit that opens and closes between each of the positive electrode and the negative electrode of the battery 72 and each of the three terminals of the reaction force motor 26.

The steering actuator 40 includes rack and pinion mechanisms 48 and 52, SPMSM (steering side motor 56), and an inverter 58.
The rack and pinion mechanisms 48 and 52 include a rack shaft 46 and pinion shafts 42 and 50 arranged with a predetermined crossing angle, and rack teeth 46a and 46b and pinion shafts formed on both ends of the rack shaft 46, respectively. The pinion teeth 42a and 50a formed in 42 and 50 are meshed with each other. The steered wheels 30 are connected to both ends of the rack shaft 46 via tie rods (not shown). The rack shaft 46 corresponds to a steered shaft.

  The pinion shaft 50 is connected to the rotating shaft 56 a of the steered side motor 56 via the steered side speed reducer 54. An inverter 58 is connected to the steered side motor 56. The rack shaft 46 is accommodated in the rack housing 44.

  In FIG. 1, among the symbols of the MOS field effect transistors (switching elements) constituting the inverter 58, those connected to each of the three terminals of the steered side motor 56 are “u, v, w”. In addition, “p” is given to the upper arm and “n” is given to the lower arm. In the following, “u, v, w” are collectively expressed as “¥”, and “p, n” are collectively expressed as “#”. That is, the inverter 58 is a switching element S ¥ p that opens and closes between the positive electrode of the battery 72 and the terminal of the steered side motor 56 and a switching that opens and closes between the negative electrode of the battery 72 and the terminal of the steered side motor 56. A series connection body with the element S ¥ n is provided. A diode D ¥ # is connected in reverse parallel to the switching element S ¥ #.

  A spiral cable device 60 is connected to the steering 10. The spiral cable device 60 is accommodated in a space defined by the first housing 62 fixed to the steering 10, the second housing 64 fixed to the vehicle body, the first housing 62 and the second housing 64, and the second housing 64. A cylindrical member 66 fixed to the housing 64 and a spiral cable 68 wound around the cylindrical member 66 are provided. The steering shaft 22 is inserted into the cylindrical member 66.

  In the steering shaft 22, an elastic member (not shown) made of a spiral spring or the like for returning the steering 10 to a neutral position for linearly moving the vehicle is coupled to the end of the steering shaft 22 opposite to the steering 10. Yes. The spiral cable 68 is an electrical wiring that connects the horn 70 fixed to the steering 10 and the battery 72 fixed to the vehicle body.

  The steering control device (control device 80) controls the steered wheels 30 to be steered according to the operation of the steering wheel 10 by operating a steer-by-wire type steering device provided with the reaction force actuator 20 and the steering actuator 40. Run. In the present embodiment, a steer-by-wire system is realized by the reaction force actuator 20 and the turning actuator 40, and the control device 80 executes control for turning the steered wheels 30 according to the operation of the steering 10. The control device 80 corresponds to a steering control unit, a reaction force control unit, and a midpoint learning unit.

  At this time, the control device 80 takes in the rotation angle θs0 of the rotating shaft 26a of the reaction force motor 26 detected by the steering side sensor 92 and the steering torque Trqs applied to the steering shaft 22 detected by the torque sensor 94. The control device 80 takes in the rotation angle θt0 of the rotation shaft 56a of the steered side motor 56 detected by the steered side sensor 90 and the vehicle speed V detected by the vehicle speed sensor 96. Further, the control device 80 takes in the lateral acceleration Yg detected by the lateral acceleration sensor 74. The lateral acceleration Yg is acceleration that acts on the center of gravity of the vehicle in a direction orthogonal to the traveling direction (front-rear direction) (left-right direction) when the vehicle turns. The control device 80 takes in the yaw rate γ detected by the yaw rate sensor 76.

  Note that the control device 80 acquires the voltage drop of the shunt resistor 86 connected to each source side of the switching element S ¥ n as currents iu, iv, iw in the inverter 58, and refers to these. Moreover, the control apparatus 80 takes in drive mode DM which shows the setting state of control patterns, such as a vehicle-mounted engine. Depending on the drive mode DM, the fuel consumption and the responsiveness (direct feeling) of the vehicle to the user's request differ. For example, the drive mode DM includes an ECO mode that optimizes the output of the engine and the like so as to improve fuel efficiency, and a normal that optimizes the output of the engine and the like so that the responsiveness to the user's request is enhanced compared to the ECO mode. A sports mode that optimizes the output of the engine or the like so as to increase the responsiveness to the user's request regardless of the mode and fuel consumption is included. This drive mode DM is switched by a switch 98 that can be operated by a user, that is, a steering wheel.

  Specifically, the control device 80 includes a central processing unit (CPU 82) and a memory 84. When the CPU 82 executes a program stored in the memory 84, the reaction force actuator 20 and the turning actuator 40 are operated. .

  FIG. 2 shows a part of processing executed by the control device 80. The process shown in FIG. 2 describes a part of the process realized by the CPU 82 executing the program stored in the memory 84 for each control cycle, for each type of process realized.

  The integration processing unit M2 converts the rotation angle θs0 detected by the steering side sensor 92 and the rotation angle θt0 detected by the steered side sensor 90 into numerical values in an angle region wider than 0 to 360 °, and thereby the rotation angle. Let θs and θt. For example, when the steering 10 is rotated to the right or left as much as possible from the neutral position where the vehicle goes straight, the rotating shaft 26a rotates a plurality of times. Therefore, in the integration processing unit M2, for example, when the rotating shaft 26a rotates twice in a predetermined direction from the state where the steering 10 is in the neutral position, the output value is set to 720 °. The integration processing unit M2 sets the output value at the neutral position to zero.

  The measurement unit setting processing unit M4 calculates the pre-processing steering angle θha by multiplying the output value of the steering side sensor 92 that has been processed by the integration processing unit M2 by the conversion coefficient Ks. Here, the conversion coefficient Ks is determined according to the rotation speed ratio between the reaction force side reduction gear 24 and the rotation shaft 26a of the reaction force motor 26, and thereby the amount of change in the rotation angle θs of the rotation shaft 26a is determined. The rotation amount of the steering 10 is converted. For this reason, the pre-processing steering angle θha is a rotation angle of the steering 10 with respect to the neutral position.

  In addition, the measurement unit setting processing unit M4 multiplies the output value of the steering-side sensor 90 that has been processed by the integration processing unit M2 by the conversion coefficient Kt to calculate the pre-processing turning angle θpa. The conversion coefficient Kt is the product of the rotation speed ratio between the steered side reduction gear 54 and the rotating shaft 56 a of the steered side motor 56. Thereby, the rotation amount of the rotating shaft 56a is converted into the rotation amount of the steering 10 when it is assumed that the steering shaft 22 and the pinion shaft 42 are connected.

  The processing in FIG. 2 is positive when the rotation angles θs and θt, the pre-processing steering angle θha, and the pre-processing steering angle θpa are rotation angles in a predetermined direction, and negative when the rotation angle is in the reverse direction. For example, the integration processing unit M2 sets the output value to a negative value when the rotating shaft 26a rotates in the reverse direction from the predetermined direction from the state where the steering 10 is in the neutral position. However, this is only an example of the logic of the control system. In particular, in this specification, when the rotation angles θs and θt, the pre-processing steering angle θha, and the pre-processing steering angle θpa are large, the amount of change from the neutral position is large. In other words, the absolute value of the parameter that can take a positive or negative value as described above is large.

The midpoint processing unit M5 obtains the turning angle θp by performing the turning angle midpoint learning process shown in FIG. 5 on the pre-processing turning angle θpa output from the measurement unit setting processing unit M4.
The midpoint processing unit M5 obtains the steering angle θh by offsetting the steering midpoint information set in advance with respect to the pre-processing steering angle θha output from the measurement unit setting processing unit M4. The steering middle point information is information set at the time of manufacturing the steering device or the like as the steering angle θh with respect to the straight traveling direction.

  In S30, the midpoint processing unit M5 determines whether or not the vehicle is in a straight traveling state. This straight traveling state refers to a state in which the pre-processing turning angle θpa output by the turning side sensor 90 is stable at a value corresponding to the midpoint.

  Specifically, in the straight traveling state, the pre-processing turning angle θpa is zero based on the output of the steering-side sensor 90, and the pre-processing turning angular velocity θpa is a time differential value of the pre-processing turning angle θpa. ′ Is also zero.

If the midpoint processing unit M5 determines that the pre-processing turning angle θpa is in a straight traveling state, the process proceeds to S34, and if it determines that the pre-processing turning angle θpa is not in a straight traveling state, the process proceeds to S40.
In S34, the midpoint processing unit M5 increments the count value C2 by +1. This count value C2 corresponds to a duration in which the pre-processing turning angle θpa is in a straight traveling state and the output of the turning actuator 40 is not zero.

  In S36, the midpoint processing unit M5 determines whether or not the count value C2 has reached a predetermined value TH2 (for example, TH2 = 10). If the count value C2 has not reached the predetermined value TH2, the process proceeds to S40, and if it has reached, the process proceeds to S38 and the count value C2 is reset to “0”.

  In S38, the midpoint processing unit M5 corrects (learns) the value of the pre-processing turning angle θpa at that time as the midpoint information of the rack shaft 46, assuming that the straight traveling state continues. Then, the midpoint processing unit M5 offsets the midpoint information of the rack shaft 46 corrected (learned) with respect to the pre-processing turning angle θpa output from the measurement unit setting processing unit M4, and sets the turning angle θp. get.

  Further, when the process shifts from S30 to S40, it is a case where the vehicle is not in the straight traveling state, and the midpoint processing unit M5 outputs from the measurement unit setting processing unit M4 without correcting (learning) the midpoint information of the rack shaft 46. The turning angle θp is obtained by offsetting the midpoint information of the rack shaft 46 that is currently set with respect to the pre-processing turning angle θpa. That is, the processing is terminated with the pre-processing turning angle θpa as the turning angle θp.

  The reaction force torque setting processing unit M6 sets the reaction force torque Trqa * based on the steering torque Trqs. The reaction torque Trqa * is set to a larger value as the steering torque Trqs is larger. The addition processing unit M8 adds the steering torque Trqs to the reaction force torque Trqa * and outputs the result.

  The reaction force setting processing unit M10 sets a steering reaction force Fir that is a force resisting the rotation of the steering wheel 10. Specifically, the reaction force setting processing unit M10 sets the base reaction force Fd according to the operation of the steering wheel 10 by the base reaction force setting processing unit M10a. Further, the reaction force setting processing unit M10 counteracts that the steering 10 is further operated to the upper limit side when the amount of rotation of the steering wheel 10 approaches the allowable maximum value by the limiting reaction force setting processing unit M10b. The limiting reaction force Fie, which is a force, is set. The reaction force setting processing unit M10 adds the base reaction force Fd and the limiting reaction force Fie by the addition processing unit M10c, and outputs this as the steering reaction force Fir.

The deviation calculation processing unit M12 outputs a value obtained by subtracting the steering reaction force Fir from the output of the addition processing unit M8.
The target steering angle calculation processing unit M20 sets the target steering angle θh * based on the output value of the deviation calculation processing unit M12. Here, a model formula expressed by the following formula (c1) that relates the output value Δ of the deviation calculation processing unit M12 and the target steering angle θh * is used.

Δ = C · θh * ′ + J · θh * ″ (c1)
In the model expressed by the above formula (c1), the steering 10 and the steered wheels 30 are mechanically connected, and the relationship between the torque of the rotating shaft that rotates with the rotation of the steering 10 and the rotation angle. It is a model that determines. In the above equation (c1), the viscosity coefficient C models the friction of the steering device, and the inertia coefficient J models the inertia of the steering device. Here, the viscosity coefficient C and the inertia coefficient J are variably set according to the vehicle speed V.

  The steering angle feedback processing unit M22 sets a target reaction force torque Trqr * that is a target value of the reaction force torque generated by the reaction force motor 26 as an operation amount for feedback control of the steering angle θh to the target steering angle θh *. To do. Specifically, the sum of the output values of the proportional element, the integral element, and the derivative element, each having a value obtained by subtracting the steering angle θh from the target steering angle θh *, is defined as a target reaction force torque Trqr *.

  The operation signal generation processing unit M24 generates an operation signal MSs for the inverter 28 based on the target reaction force torque Trqr * and outputs the operation signal MSs to the inverter 28. For example, a known command force torque value qqr * is set based on a q-axis current command value, and a dq-axis voltage command value is set as an operation amount for feedback control of the dq-axis current to the command value. This can be realized by current feedback control. The d-axis current may be controlled to zero, but when the reaction motor 26 has a high rotational speed, the field weakening control may be executed by setting the absolute value of the d-axis current to a value larger than zero. . However, it is also possible to set the absolute value of the d-axis current to a value larger than zero in the low rotation speed region.

  The steering angle ratio variable processing unit M26 sets a target operating angle θa * for variably setting a steering angle ratio, which is a ratio between the steering angle θh and the turning angle θp, based on the target steering angle θh *. The addition processing unit M28 calculates the target turning angle θp * by adding the target operating angle θa * to the target steering angle θh *.

  The turning angle feedback processing unit M32 sets a target turning torque Trqt * generated by the turning-side motor 56 as an operation amount for performing feedback control of the turning angle θp to the target turning angle θp *. Specifically, the sum of the output values of the proportional element, the integral element, and the derivative element, each having a value obtained by subtracting the turning angle θp from the target turning angle θp *, is defined as a target turning torque Trqt *.

  The operation signal generation processing unit M34 generates an operation signal MSt for the inverter 58 based on the target turning torque Trqt * and outputs the operation signal MSt to the inverter 58. This can be performed in the same manner as the operation signal generation processing by the operation signal generation processing unit M24.

The maximum value selection processing unit M36 selects and outputs the larger value (maximum value θe) of the target steering angle θh * and the target turning angle θp *.
The base reaction force setting processing unit M10a receives the target turning angle θp * as an input. On the other hand, the limiting reaction force setting processing unit M10b sets the limiting reaction force Fie with the maximum value θe as an input. This is both when the rack shaft 46 is displaced in the axial direction and immediately before the end of the rack shaft 46 comes into contact with the rack housing 44 (rack stopper) and immediately before the steering 10 rotates to the upper limit value determined from the spiral cable 68. In FIG. 4, the steering force is set to increase the force that resists the steering 10 from further increasing the magnitude of the steering angle. This will be described below.

  FIG. 3 shows the relationship between the upper limit values θhH and θpH of the steering angle θh and the turning angle θp. As shown in the drawing, in the present embodiment, the upper limit value θhH of the steering angle θh and the upper limit value θpH of the turning angle θp are substantially equal. This is realized by setting the measurement unit of the steering angle θh and the turning angle θp by the measurement unit setting processing unit M4. In the present embodiment, when the steering shaft 22 is in a connected state, when the rack shaft 46 is displaced in the axial direction until it comes into contact with the rack housing 44, the spiral is set so that the steering 10 can be further rotated slightly. The length of the cable 68 has a slight margin. For this reason, the measurement unit setting processing unit M4 sets the steering angle θh as the rotation angle of the steering wheel 10 and the turning angle θp as the rotation angle of the steering wheel 10 when the target operation angle θa * is assumed to be zero. The upper limit value θhH of the angle θh and the upper limit value θpH of the turning angle θp are substantially equal.

  In the present embodiment, a common threshold value θen is provided for the steering angle θh and the turning angle θp, and before the steering angle θh reaches the upper limit value θhH and before the turning angle θp reaches the upper limit value θpH, the steering 10 Increase reaction force control. The limiting reaction force setting processing unit M10b illustrated in FIG. 2 includes a map that defines the relationship between the maximum value θe and the limiting reaction force Fie. In this map, the limiting reaction force Fie becomes larger than zero when the maximum value θe is equal to or larger than the common threshold θen, and in particular, the limiting reaction force Fie exceeds the common threshold θen to some extent. In other words, the value is set so large that it cannot be operated by human power any more. FIG. 2 only shows that the limiting reaction force Fie increases as the maximum value θe increases from zero in a predetermined rotation direction. However, this is a case where the maximum reaction angle Fie increases in the direction opposite to the predetermined rotation direction. Even so, the absolute value of the limiting reaction force Fie increases. However, the limiting reaction force Fie in the process of FIG. 2 is negative when the direction is opposite to the predetermined rotation direction.

  The determination unit M40 takes in the lateral acceleration Yg detected by the lateral acceleration sensor 74, the yaw rate γ detected by the yaw rate sensor 76, and the steering angle θh, and executes the determination process shown in the flowchart of FIG.

  In S100, the determination unit M40 determines whether or not the vehicle is traveling straight. Specifically, if the lateral acceleration Yg = 0, the yaw rate γ = 0, and the steering angle θh = 0, it is determined that the vehicle is traveling straight, and the process proceeds to S110. Otherwise, the process proceeds to S130.

  In S110, the determination unit M40 determines that the duration time during which the output torque Tm based on the operation signal MSs that is the output of the reaction force actuator 20 exceeds the abnormality determination value Tmra (that is, a first count value described later) is predetermined. It is determined whether or not the time tr1 is exceeded.

  Here, the determination unit M40 is in a state where the vehicle cannot normally travel (hereinafter referred to as “abnormal state”) when the duration of the output torque Tm exceeding the abnormality determination value Tmra is equal to or longer than the predetermined time tr1. It determines with driving | running | working in the state in which the steered wheel 30 shifted | deviated with respect to the straight direction which is advancing direction, and transfers to S120. Otherwise, the determination unit M40 proceeds to S140 as a state where the vehicle can travel normally (hereinafter referred to as “normal state”). The predetermined time tr1 corresponds to a straight traveling determination time, and is a value that is obtained by an experiment so that an abnormal state can be determined. The abnormality determination value Tmra is a value that is obtained through an experiment so that it can be determined that the output torque Tm is output and the steering reaction force is applied.

  When the output torque Tm exceeds the abnormality determination value Tmr, the determination unit M40 increments the first count value for measuring the duration time by +1 every control cycle for executing this flowchart, and the output torque Tm When the abnormality determination value is less than Tmr, the first count value is reset to zero.

  In S120, the determination unit M40 determines that there is an abnormal state in S110, so the abnormality flag P is set to “1” and is output to the switching unit M10aae of the axial force distribution calculation unit M10aa shown in FIG.

  In S140, since the determination unit M40 determines that the state is normal in S110, the abnormality flag P is reset to “0” and is output to the switching unit M10aae of the axial force distribution calculation unit M10aa.

  In S130, the lateral acceleration Yg> the threshold value Ygr, the yaw rate γ> the threshold value γr, the steering angle θh> the threshold value θhr, and the duration time during which the output torque Tm based on the operation signal MSs does not exceed the abnormality determination value Tmrb. It is determined whether or not the predetermined time tr2 is exceeded. Here, the predetermined time tr2 corresponds to a turning determination time, and is a value that is obtained by an experiment so that turning can be determined. The predetermined time tr2 is a value obtained by an experiment assuming that the output torque Tm is being output and the vehicle is turning. Further, the abnormality determination value Tmrb is a value that is obtained by an experiment so that it can be determined that the output torque Tm is not output and the steering reaction force is not applied.

  The determination unit M40 determines that the lateral acceleration Yg> the threshold value Ygr, the yaw rate γ> the threshold value γr, the steering angle θh> the threshold value θhr, and the duration that the output torque Tm does not exceed the abnormality determination value Tmrb (that is, a second count value described later). ) Is determined to be abnormal if it is equal to or longer than the predetermined time tr2. That is, the determination unit M40 determines that the vehicle is traveling so as to turn with the steered wheels 30 facing the traveling direction of the vehicle, that is, an abnormal state, and the process proceeds to S120. If so, the process proceeds to S140 as a normal state.

  When the lateral acceleration Yg> the threshold Ygr, the yaw rate γ> the threshold γr, the steering angle θh> the threshold θhr, and the output torque Tm does not exceed the abnormality determination value Tmrb, the determination unit M40 performs control to execute this flowchart. In each cycle, the second count value for counting the duration time is incremented by +1. Otherwise, the second count value is reset to zero.

Note that the threshold value Ygr, the threshold value γr, and the threshold value θhr are preset values and are constant values, and are obtained by tests or the like.
In addition, the determination of the straight traveling state in S100 is not limited to the lateral acceleration Yg = 0, the yaw rate γ = 0, and the steering angle θh = 0, but the lateral acceleration Yg, the yaw rate γ, and the steering angle θh. It may be determined that the vehicle is in a straight traveling state when it is within a predetermined value range near 0, and that it is in a turning state otherwise.

  As shown in FIG. 2, in the present embodiment, the reaction force setting processing unit M10 determines the ideal axial force Fib and the estimated axial force Fer so as to reflect the axial force applied to the steered wheels 30 from the road surface. As a distribution component distributed by distribution, an axial force distribution calculation unit M10aa that executes a calculation for setting a base reaction force Fd is provided. The axial force applied to the steered wheels 30 is road surface information transmitted from the road surface to the steered wheels 30.

  Further, the reaction force setting processing unit M10 is an ideal value of the axial force acting on the steered wheels 30 (the transmission force transmitted to the steered wheels 30) among the components of the base reaction force Fd, and road surface information is not reflected. An ideal axial force calculation unit M10ab that calculates an ideal axial force Fib that is an ideal component is provided. The ideal axial force calculation unit M10ab calculates an ideal axial force Fib based on the target turning angle θp *. For example, the absolute value of the ideal axial force Fib is set to increase as the absolute value of the target turning angle θp * increases.

  The reaction force setting processing unit M10 includes an estimated axial force calculation unit M10ac. The estimated axial force calculation unit M10ac is an estimated value of the axial force acting on the steered wheels 30 (the transmission force transmitted to the steered wheels 30) among the components of the base reaction force Fd, and the road surface on which road surface information is reflected. An estimated axial force Fer as a component is calculated. Specifically, the estimated axial force calculation unit M10ac acquires currents iu, iv, iw that are actual current values of the steered side motor 56, and based on the q-axis current iq calculated thereby, the estimated axial force Fer is calculated. The calculation of the q-axis current ip can be realized based on the rotation angle θt0 of the steered side motor 56 by a conversion process to the dq-axis coordinate system, which is a rotating coordinate system. Then, the estimated axial force calculation unit M10ac calculates the estimated axial force Fer by multiplying the q-axis current iq by a predetermined coefficient K1.

  Here, the predetermined coefficient K1 is set based on the gear ratio of the steered side reduction gear 54, the ratio of the torque of the pinion shaft 50 to the axial force of the rack shaft 46, and the torque constant. That is, the torque of the steered side motor 56 is determined by multiplying the q-axis current iq by a constant. The torque of the steered side motor 56 is converted by the steered side speed reducer 54 and the like and applied to the rack shaft 46. Therefore, the axial force applied to the rack shaft 46 by the steered side motor 56 can be calculated by multiplying the q-axis current iq by the predetermined coefficient K1. When the axial force applied to the rack shaft 46 by the steered side motor 56 and the axial force applied from the road surface to the steered wheel 30 can be regarded as a balanced relationship, based on the q-axis current iq, Thus, the axial force applied from the road surface can be estimated as the estimated axial force Fer. The estimated axial force Fer is a component that reflects at least road surface information.

  As shown in FIG. 4, the axial force distribution calculation unit M10aa is a gain calculation unit M10aaa that calculates a distribution gain Gib and a distribution gain Ger that are distributions for distributing the ideal axial force Fib and the estimated axial force Fer. And a switching unit M10aae. The gain calculation unit M10aaa includes a three-dimensional map that defines the relationship between the vehicle speed V, each of the distribution gains Gib and Ger, and the drive mode DM selected by the user, and receives the drive mode DM and the vehicle speed V as inputs. Each distribution gain Gib, Ger is map-calculated. The distribution gain Gib has a smaller value when the vehicle speed V is high than when the vehicle speed V is small, while the distribution gain Ger has a larger value than when the vehicle speed V is high.

  For example, when the drive mode DM is the ECO mode or the normal mode, the distribution gains Gib and Ger are set so that the sum is 1. On the other hand, each of the distribution gains Gib and Ger increases the value of the distribution gain Ger so that the sum exceeds 1, for example, when the drive mode DM is the sports mode. In particular, the distribution gain Ger increases as the vehicle speed V increases. It is set to increase the value.

  The axial force distribution calculation unit M10aa multiplies the output value (ideal axial force Fib) of the ideal axial force calculation unit M10ab by the distribution gain Gib by the multiplication processing unit M10aaab. Further, the axial force distribution calculation unit M10aa multiplies the output value of the switching unit M10aae by the distribution gain Ger by the multiplication processing unit M10aaac. Further, the axial force distribution calculation unit M10aa adds the value obtained by multiplying the ideal axial force Fib by the distribution gain Gib and the value obtained by multiplying the output value of the switching unit M10aae by the distribution gain Ger in the addition processing unit M10aa. The base reaction force Fd is calculated and output.

  Here, when the abnormality flag P is “0” (normal state), the switching unit M10aae outputs the output value (estimated axial force Fer) of the estimated axial force calculation unit M10ac to the multiplication processing unit M10aac for distribution. Multiply by gain Ger. Therefore, when the abnormality flag P is “0”, the axial force distribution calculation unit M10aa uses the addition processing unit M10aa to multiply the ideal axial force Fib by the distribution gain Gib and the estimated axial force Fer to the distribution gain Ger. The base reaction force Fd is calculated and output by adding the multiplied ones.

  On the other hand, when the abnormality flag P is “1” (in an abnormal state), the switching unit M10aae outputs the value obtained by multiplying the estimated axial force Fer by a predetermined coefficient L to the multiplication processing unit M10aac. .

  The predetermined coefficient L is a value that decreases the estimated axial force Fer and is a value of 0 ≦ L <1. However, as a value that decreases the estimated axial force Fer, the predetermined coefficient L is 0 or 0. More preferably, the value is in the vicinity. The predetermined coefficient L is not limited to a fixed value, and may be a variable value that gradually decreases each time the output of the abnormality flag P of “1” continues.

Therefore, when the abnormality flag P is “1”, the distribution of the estimated axial force Fer is reduced and the distribution of the ideal axial force Fib is increased as compared with the normal state, and the appropriate steering reaction force Fir is obtained. .
That is, when it is determined that the steering angle of the steering wheel 10 is a value indicating the straight traveling direction (0 in the present embodiment) and is in an abnormal state as in S120, the distribution of the estimated axial force Fer is reduced to 0 or 0. The value is near. In this case, since the target turning angle θp * is an angle in the straight traveling direction, the ideal axial force can be set to 0 or a value close to 0.

  Further, when it is determined that the vehicle is in an abnormal state as in S120 when the vehicle is turning, the distribution of the estimated axial force Fer decreases, and becomes 0 or a value close to 0. In this case, the target turning angle θp * is, for example, an angle in the traveling direction of the vehicle as illustrated in FIG. 8D, and the ideal axial force is set to a value corresponding to the steering angle of the steering 10. Can do. As a result, the steered wheel 30 is punctured or the air pressure is reduced. Thus, even when the midpoint learning is performed in a state where the midpoint of the turning shaft does not coincide with the midpoint when the steered wheels 30 are directed straight, the steering wheel steers the steering 10 naturally. can do.

According to the present embodiment described above, the following operations and effects are achieved.
(1) The control device 80 of the present embodiment includes a midpoint learning unit that learns the midpoint of the detected turning angle, and a reaction force actuator that applies a steering reaction force against the operation of the steering 10. 20 is provided. In addition, the control device 80 includes a steering actuator 40 that steers the steered wheel 30 via the rack shaft 46 (steering shaft) in a state where the power is disconnected between the steered wheel 30 and the steering 10. In addition, the control device 80 has a function of a turning control unit that controls the turning actuator 40 according to the steering state of the steering 10. Further, the control device 80 determines the distribution of the estimated axial force Fer based on the road surface information and the ideal axial force Fib based on the target turning angle calculated based on the steering angle, and applies the steering reaction force. It has a function as a reaction force control unit for controlling the reaction force actuator. Further, the control device 80 serves as a reaction force control unit to reduce the distribution of the estimated axial force Fer in the steering reaction force when the vehicle travels in a state where the steered wheels 30 are deviated from the traveling direction of the vehicle. .

  As a result, when the steered wheels 30 are punctured or the air pressure is reduced, and the vehicle travels in a state where the steered wheels 30 deviate from the traveling direction of the vehicle, the steered shaft midpoint and the steered wheels 30 face the straight direction. Even when the midpoint learning is performed in a state where the midpoint does not coincide with the middle point, the steering person can steer the steering 10 naturally.

  (2) In the control device 80 (reaction force control unit), the lateral acceleration Yg acting on the vehicle, the yaw rate γ, and the steering angle of the steering 10 are values indicating the straight traveling direction, and the state in which the steering reaction force is applied is predetermined. The case where the time tr1 (straight-running determination time) is continued is a case where the steered wheels 30 are traveling in a state deviated from the straight-running direction which is the traveling direction of the vehicle.

  As a result, it is possible to determine the case where the vehicle is traveling with the steered wheels 30 being deviated from the straight traveling direction that is the traveling direction of the vehicle. After this determination, the distribution of the estimated axial force Fer in the reaction force can be reduced.

  (3) The control device 80 (reaction force control unit) turns when the lateral acceleration Yg acting on the vehicle, the yaw rate γ, and the steering angle of the steering 10 are not values indicating the straight traveling direction, and the steering reaction force is not applied. The case where the determination time is continued is a case where the steered wheels 30 are traveling in a state of being deviated from the turning direction which is the traveling direction of the vehicle.

  As a result, it can be determined that the vehicle is traveling so as to turn with the steered wheels 30 facing the traveling direction of the vehicle. After this determination, the distribution of the estimated axial force Fer in the reaction force can be reduced.

  (4) The control device 80 (reaction force control unit) gradually reduces the distribution of the estimated axial force Fer in the steering reaction force when the vehicle travels with the steered wheels 30 shifted with respect to the traveling direction of the vehicle. I try to make it smaller.

When the vehicle travels with the steered wheels 30 displaced from the traveling direction of the vehicle, the distribution of the estimated axial force Fer in the steering reaction force can be gradually reduced to be small.
(5) Further, the control device 80 of the present embodiment, as the reaction force control unit, distributes the ideal axial force in the steering reaction force Fir when the steered wheel 30 travels with a deviation from the traveling direction of the vehicle. Try to increase.

  As a result, when the steered wheels 30 are punctured or the air pressure is reduced, and the vehicle travels in a state where the steered wheels 30 deviate from the traveling direction of the vehicle, the steered shaft midpoint and the steered wheels 30 face the straight direction. Even when the midpoint learning is performed in a state where the midpoint does not coincide with the middle point, the steering person can steer the steering 10 naturally.

In addition, the said embodiment can also be implemented with the following forms.
In the above embodiment, the steering control device of the clutchless steer-by-wire type steering device is embodied. For example, as shown in FIG. 7, the steering shaft 22 and the pinion shaft 42 are mechanically connected and disconnected. The present invention may be applied to a steer-by-wire type steering control device with a clutch 12 that performs the above.

  In the flowchart of FIG. 6 of the above embodiment, S130 may be omitted, and S100 and S110 may be a single step, or S110 may be omitted and S100 and S130 may be a single step.

  In the above embodiment, the midpoint processing unit M5 is provided to correct (learn) the midpoint information of the rack shaft 46 in the control cycle of the CPU 82. However, the present invention is not limited to this mode. Correction (learning) may be performed at a predetermined timing, such as when the is turned on.

  The values of the distribution gains Gib and Ger may be set so that the sum is 1 regardless of the drive mode DM. In this case, the gain calculation unit M10aaa may perform a map calculation on one of the distribution gains Gib and Ger, and calculate the remaining distribution gain by subtracting the obtained distribution gain from 1. The distribution gains Gib and Ger may be set so that the sum is less than 1.

  Parameters for calculating the distribution gains Gib and Ger include the steering angle θh, the turning angle θp, the rotational angular velocity around the vertical axis passing through the center of gravity of the vehicle (so-called yaw rate), and the left and right turning wheels 30 Alternatively, parameters such as a wheel speed difference of a wheel speed sensor provided respectively may be used instead of the drive mode DM or the vehicle speed V. The parameters including the drive mode DM and the vehicle speed V may be used alone or in any combination. The distribution gains Gib and Ger may be calculated based on information obtained from GPS or the like. As described above, the steering feeling can be adjusted by arbitrarily selecting a parameter to be regarded as important, and the degree of freedom in adjusting the steering feeling can be increased.

  The relationship between the distribution gain Gib and Ger and the vehicle speed V can be changed. For example, the distribution gain Gib may be a value that decreases as the vehicle speed V increases. The distribution gain Ger may be a value that increases as the vehicle speed V increases. That is, the relationship with the vehicle speed V can be set for each of the distribution gains Gib and Ger according to the vehicle specifications, the vehicle usage environment, and the like.

  -The type of drive mode DM may be increased or decreased according to vehicle specifications. In this case, a map may be provided according to the type of drive mode DM. Further, the drive mode DM does not have to be selected by the user. For example, the drive mode DM may be automatically selected by the control device 80 (vehicle side) according to the traveling state of the vehicle, the user's operation, or the like. Good.

In the embodiment, the limiting reaction force setting processing unit M10b may be deleted from the reaction force setting processing unit M10.
In the embodiment, the reaction force motor 26 and the steered side motor 56 are not limited to SPMSM, and for example, an IPMSM may be used.

  In the embodiment, if the steering actuator 40 is a rack assist type, for example, a steering side motor 56 is arranged on the same axis as the rack shaft 46, or a steering side motor is parallel to the rack shaft 46. 56 may be arranged.

  In the embodiment, as the control device 80, dedicated hardware (ASIC) may be provided in addition to the CPU 82 and the memory 84. Then, a part of the processing of the CPU 82 may be hardware processing, and the CPU 82 may acquire it from the hardware.

-When increasing the distribution of ideal axial force, it may be increased gradually.
The determination of the straight traveling state may be made based on the time for which the pre-processing steering angle θha maintains the neutral position.

  In the above embodiment, the reaction force actuator 20 and the turning actuator 40 are controlled by the single control device 80. However, the control device that controls the reaction force actuator 20 and the turning actuator 40, respectively. It may be provided individually.

  In this embodiment, the rack shaft 46 is supported by the rack and pinion mechanism 48 so that one end of the rack shaft 46 can reciprocate. However, for example, the pinion shaft 42 is omitted and the rack and pinion mechanism 48 is omitted. May be. In this case, a rack bush or the like that supports the rack shaft 46 may be provided inside the rack housing 44. In this case, the rack teeth 46a can be eliminated.

10 ... Steering, 12 ... Clutch, 20 ... Reaction force actuator,
22 ... Steering shaft, 24 ... Reaction force side reduction gear, 26 ... Reaction force motor,
26a ... rotating shaft, 28 ... inverter, 30 ... steered wheel,
40 ... steering actuator, 42 ... pinion shaft, 44 ... rack housing,
46 ... Rack shaft (steering shaft), 46b ... Rack teeth, 50 ... Pinion shaft,
50a ... pinion teeth, 52 ... rack and pinion mechanism,
54 ... Steering side reduction gear, 56 ... Steering side motor, 56a ... Rotating shaft,
58 ... Inverter, 60 ... Spiral cable device,
62 ... 1st housing, 64 ... 2nd housing, 66 ... Cylindrical member,
68 ... spiral cable, 70 ... horn, 72 ... battery,
74 ... Lateral acceleration sensor, 76 ... Yaw rate sensor,
80 ... control device (steering control unit, reaction force control unit, midpoint learning unit), 82 ... CPU,
84 ... Memory, 86 ... Shunt resistance, 90 ... Steering side sensor,
92 ... steering side sensor, 94 ... torque sensor,
96 ... Vehicle speed sensor, 98 ... Switch, 100 ... Steering wheel,
110 ... steering shaft, 120 ... steering,
M2 ... Integration processing unit, M4 ... Measurement unit setting processing unit, M5 ... Midpoint processing unit,
M10 ... reaction force setting processing unit, M10a ... base reaction force setting processing unit,
M10aa ... axial force distribution calculation unit, M10aaa ... gain calculation unit,
M10aab ... multiplication processing unit, M10aac ... multiplication processing unit,
M10aad ... addition processing unit, M10aae ... switching unit,
M10ab: ideal axial force calculation unit, M10ac: estimated axial force calculation unit,
M10b: reaction force setting processing unit for restriction, M10c: addition processing unit,
M12 ... deviation calculation processing unit, M20 ... target steering angle calculation processing unit,
M22 ... Steering angle feedback processing unit, M24 ... Operation signal generation processing unit,
M26 ... Steering angle ratio variable processing unit, M28 ... Addition processing unit,
M32 ... Steering angle feedback processing unit, M34 ... Operation signal generation processing unit,
M36 ... maximum value selection processing unit, M40 ... determination unit.

Claims (5)

A midpoint learning unit for learning the midpoint of the detected turning angle;
A reaction force actuator that applies a steering reaction force that resists steering operation;
A steered actuator that steers the steered wheel via a steered shaft under a power cut-off state between the steered wheel and the steering;
A steering control unit for controlling the steering actuator according to a steering state of the steering;
Reaction force control that controls the reaction force actuator to determine the distribution of the estimated axial force based on the road surface information and the ideal axial force based on the target turning angle calculated based on the steering angle and to apply the steering reaction force A steer-by-wire steering device having a control part,
The reaction force control unit is a steering control device that reduces the distribution of the estimated axial force in the steering reaction force when the vehicle travels in a state where the steered wheels are deviated from the traveling direction of the vehicle.   The reaction force control unit is a value in which the lateral acceleration acting on the vehicle, the yaw rate and the steering angle of the steering are values indicating a straight traveling direction, and the state where the steering reaction force is applied continues the straight traveling determination time. The steering control device according to claim 1, wherein the vehicle travels in a state where the steered wheels are deviated from a straight traveling direction that is a traveling direction of the vehicle.   The reaction force control unit, when the lateral acceleration acting on the vehicle, the yaw rate, and the steering angle of the steering are not values indicating a straight traveling direction, and the state where the steering reaction force is not applied continues the turn determination time. The steering control device according to claim 1 or 2, wherein the steered wheel is traveling in a state in which the steered wheels are deviated from a turning direction that is a traveling direction of the vehicle.   The said reaction force control part makes it small by decreasing gradually the distribution of the said estimated axial force in the said steering reaction force, when driving | running | working a vehicle with the said steered wheel shifting | deviating with respect to the advancing direction of a vehicle. 4. The steering control device according to any one of items 3.   The reaction force control unit increases the distribution of the ideal axial force in the steering reaction force when the vehicle travels in a state where the steered wheels are deviated from the traveling direction of the vehicle. The steering control device according to claim 1.