Steering control device

Abstract

A steering control device (50) controls an electric motor (21) for turning a steering wheel (12) of a vehicle in conjunction with a steering wheel (11) based on a command value. The steering control device (50) includes an electronic control unit. The electronic control unit is configured to calculate a feedback control torque to be reflected in the command value. The electronic control unit is configured to calculate a disturbance torque based on the feedback control torque and a predetermined angle. The electronic control unit is configured to correct the feedback control torque by using the disturbance torque. The electronic control unit is configured to correct the command value reflecting the corrected feedback control torque based on an applied torque.

Description

TECHNICAL FIELD

[0001] The present application relates to a steering control device. BACKGROUND

[0002] A control device is known that controls electric power supplied to a motor for controlling an autonomous driving system, a driving support system, or a steering system such as a steer-by-wire system. For example, the control device of Japanese Unexamined Patent Application Publication No. 2018-183046 (JP 2018-183046 A) calculates a target motor torque (target automatic steering torque) based on a target steering angle set by a control device for autonomous driving control, and calculates a target motor current by dividing the calculated target motor torque by a torque constant of the motor. The control device feeds back the current supplied to the motor so that the motor current detected by a current detection circuit coincides with the target motor current.

[0003] The control device of JP 2018-183046 A includes a disturbance observer. The disturbance observer estimates a disturbance torque based on a rotation angle of the motor detected by a rotation angle sensor and a target motor torque calculated based on the target steering angle. The disturbance torque is a torque other than the motor torque that affects the steering angle. The control device calculates the target motor torque by using the disturbance torque calculated by the disturbance observer. By compensating for the disturbance torque, higher-precision motor control is achieved. SUMMARY

[0004] However, in the control device of JP 2018-183046 A, the following problem exists. For example, when autonomous driving control is being performed, the entity that operates the steering wheel is not the driver but the control device for autonomous driving control. For this reason, it is conceivable that the driver does not actively operate the steering wheel but drives the vehicle in a hands-off state in which the hands are off the steering wheel. In this hands-off state, resonance in a specific frequency range due to inertia of the steering wheel can occur. As a difference between a frequency characteristic of a vehicle device including the steering system as a result of the resonance occurring and a frequency characteristic of a nominal device (a model simulating the steering system) of the disturbance observer increases, there is a problem that followability of an actual steering angle to a target steering angle decreases.

[0005] The present application ensures followability of an actual angle to a target angle.

[0006] An aspect of the present application relates to a steering control device. The steering control device controls an electric motor for turning a steering wheel of a vehicle linked to a steering wheel based on a command value. The command value is calculated in accordance with a target angle that can be converted into an angle of a wheel turning angle of the steering wheel, and the target angle is determined by a main control device on board. The steering control device includes an electronic control unit. The electronic control unit is configured to calculate a feedback control torque to be reflected in the command value by executing feedback control. The feedback control is control to make a predetermined angle follow the target angle. The predetermined angle is an angle that can be converted into the wheel turning angle and is detected by a first sensor. The electronic control unit is configured to calculate a disturbance torque based on the calculated feedback control torque and the predetermined angle. The disturbance torque is a torque that affects the predetermined angle and is different from a torque to be generated by the electric motor. The electronic control unit is configured to correct the calculated feedback control torque by using the calculated disturbance torque. The electronic control unit is configured to correct the command value that reflects the corrected feedback control torque based on an applied torque. The applied torque is a torque to be applied to the steering wheel and is detected by a second sensor.

[0007] When control of the electric motor based on the target angle determined by the main control device is being executed, an entity that operates the steering wheel is not the driver but the main control device. For this reason, it is conceivable that the driver does not actively operate the steering wheel, but drives the vehicle in a hands-off state in which the hands are away from the steering wheel. In the hands-off state, resonance in a certain frequency range due to inertia of the steering wheel can occur. With an increase in a difference between a frequency characteristic of a vehicle device including an actual device to be controlled by the steering control device as a result of the resonance and a frequency characteristic of a nominal device of the disturbance observer, there is a problem that followability of an actual angle to the target angle decreases.

[0008] In this aspect, with the above configuration, when control of the electric motor based on the target angle determined by the main control device is being executed, for example, when the vehicle is traveling in the hands-off state, a torque due to inertia of the steering wheel is detected by the second sensor. The command value that reflects the feedback control torque corrected by the electronic control unit is corrected based on the detected inertia torque of the steering wheel, so a final command value that compensates for the inertia torque of the steering wheel is obtained. The electric motor is controlled based on the final command value, so followability of the actual angle to the target angle is ensured.

[0009] In the steering control device, the electronic control unit can be configured to subtract the applied torque from the command value that reflects the corrected feedback control torque.

[0010] With the above configuration, a final command value that compensates for the inertia torque of the steering wheel is obtained. In the steering control device, the electronic control unit can be configured to subtract the applied torque from the calculated disturbance torque.

[0011] With the above configuration, the disturbance torque that compensates for the inertial torque of the steering wheel is obtained. Therefore, the feedback control torque corrected by the disturbance torque, and as an extension, the command value that reflects the corrected feedback control torque is the feedback control torque and the command value that compensates for the inertial torque of the steering wheel.

[0012] In the steering control device, the electronic control unit can be configured to calculate the feedforward control torque based on the second-order time derivative of the target angle. The electronic control unit can be configured to subtract the disturbance torque from a value obtained by adding the feedforward control torque and the feedback control torque.

[0013] With the above configuration, when the motor is controlled by using the feedforward control torque, the response of the motor control is further increased.

[0014] With the above configuration, the following performance of the actual angle to the target angle is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0015] Features, advantages, and technical and industrial significance of exemplary embodiments of the present application will be described below with reference to the accompanying drawings, wherein like numerals denote like elements, and wherein:

[0016] Figure 1 is a configuration diagram of an electric power steering device in which a steering control device according to an embodiment is installed;

[0017] Figure 2 is a control block diagram of a steering control device according to an embodiment;

[0018] Figure 3 is a control block diagram of a command value calculation unit in an embodiment;

[0019] Figure 4 is a control block diagram of an angle feedback control unit in an embodiment; and

[0020] Figure 5 is a schematic diagram showing a physical model of an electric power steering device in an embodiment. DETAILED DESCRIPTION

[0021] Hereinafter, a first embodiment in which the steering control device is implemented as a control device of an electric power steering (EPS) device will be described. As shown in Figure 1 The EPS 10 includes a steering shaft 13, a pinion shaft 14, and a wheel steering shaft 15 as a power transmission path between the steering wheel 11 and a pair of steering wheels 12. The wheel steering shaft 15 extends in the vehicle width direction (widthwise direction) of the vehicle 1. Figure 1The steering wheel 12 extends in the left and right directions. The steering wheels 12 are coupled to both ends of the wheel steering shaft 15 via tie rods 16. A pinion shaft 14 is configured to intersect the wheel steering shaft 15. The pinion teeth 14a of the pinion shaft 14 mesh with the rack teeth 15a of the wheel steering shaft 15. The wheel steering shaft 15 moves linearly with the rotation of the steering wheel 11. This linear movement of the wheel steering shaft 15 is transmitted to the left and right steering wheels 12 via tie rods 16, resulting in a change in the wheel steering angle θ of the steering wheels 12. w .

[0022] EPS 10 includes a motor 21 and a reduction gear 22 as components for generating auxiliary force, which is a force used to assist the driver in steering. The motor 21 acts as an auxiliary motor, serving as the source of the auxiliary force. For example, a three-phase brushless motor is used as the motor 21. The motor 21 is coupled to a pinion shaft 23 via the reduction gear 22. The pinion teeth 23a of the pinion shaft 23 mesh with the rack teeth 15b of the wheel steering shaft 15. The reduction gear 22 reduces the rotational speed of the motor 21, and the reduced rotational force is transmitted as an auxiliary force to the wheel steering shaft 15 via the pinion shaft 23. The wheel steering shaft 15 moves along the width direction of the vehicle as the motor 21 rotates.

[0023] EPS 10 includes a control unit 50. The control unit 50 controls the motor 21 based on results detected by various sensors. These sensors include a torque sensor 51, a vehicle speed sensor 52, and a rotation angle sensor 53. The torque sensor 51 measures the steering torque T based on the amount of torsion of the steering shaft 13. h The testing is performed. Steering torque is the torque applied to the steering shaft 13 by rotating the steering wheel 11. Vehicle speed sensor 52 detects the vehicle speed V. Rotation angle sensor 53 is located in the motor 21. Rotation angle sensor 53 detects the rotation angle θ of the motor 21. m The control device 50 executes commands based on the steering torque T by energizing the motor 21. h Assistive control that generates auxiliary force. Control device 50 controls the power supplied to motor 21 based on the steering torque T detected by torque sensor 51. h The vehicle speed V detected by vehicle speed sensor 52; and the rotation angle θ detected by rotation angle sensor 53. m The control device 50 may include an electronic control unit.

[0024] The vehicle can be equipped with an autonomous driving system that implements various driving support functions for further improving the safety or convenience of the vehicle, or automatic driving functions with which the system takes over the driving operation. In this case, the vehicle is equipped with a main control device 500 that generally controls the control devices of various vehicle-mounted systems. The main control device 500 determines the optimal control method based on the state of the vehicle at any given time, and instructs the various vehicle-mounted control devices to perform control in accordance with the determined control method, respectively.

[0025] The main control device 500 intervenes in the steering control performed by the control device 50. The main control device 500 switches the autonomous driving control function of the main control device 500 between an on state (enabled) and an off state (disabled) in response to the operation of a switch (not shown) provided at the driver's seat or the like. The autonomous driving control function also includes a driving support control function for further improving the safety or convenience of the vehicle.

[0026] For example, the main control device 500 calculates an additional angle command value as a command value θ * for causing the vehicle to travel within the target lane in a state in which the autonomous driving control function is in the on state. The additional angle command value is a target value (an angle to be added to the current pinion angle θ p ) of the pinion angle θ p required for the vehicle to travel along the lane for the travel state of the vehicle at any given time. The control device 50 controls the motor 21 by using the command value θ * calculated by the main control device 500. The pinion angle θ p is convertible to the wheel steering angle θ w of the steering wheel 12.

[0027] Next, the control device 50 will be described in detail. As shown in Figure 2 , the control device 50 includes a pinion angle calculation unit 61, a command value calculation unit 62, and a conduction control unit 63.

[0028] The pinion angle calculation unit 61 calculates the pinion angle θ p as the rotation angle of the pinion shaft 23 based on the rotation angle θ m of the motor 21 detected by the rotation angle sensor 53. The pinion angle calculation unit 61 calculates the pinion angle θ p by, for example, dividing the rotation angle θ m of the motor 21 by the reduction ratio of the reduction mechanism 22.

[0029] The pinion angle calculation unit 61 can calculate the rotation angle of the pinion shaft 14 as the pinion angle θ pIn this case, the pinion angle calculation unit 61 calculates the rotation angle θ of the motor 21, for example. m The pinion angle θ, which is the rotation angle of the pinion shaft 14, is calculated by dividing by the reduction ratio of the components from the motor 21 to the pinion shaft 14. p .

[0030] The command value calculation unit 62 is based on the steering torque T detected by the torque sensor 51. h The auxiliary command value T is calculated based on the vehicle speed V detected by the vehicle speed sensor 52. * Auxiliary instruction value T * The instruction is used as an auxiliary torque to generate the rotational force by motor 21. The instruction value calculation unit 62 calculates the torque as the steering torque T increases. h The absolute value of the auxiliary command value T increases or has a larger absolute value as the vehicle speed V decreases. * .

[0031] The power control unit 63, based on the auxiliary command value T * Power is supplied to motor 21. Specifically, the power supply control unit 63 is configured as follows. The power supply control unit 63 is based on the auxiliary command value T. * The current command value is calculated as the target value of the current to be supplied to the motor 21. The power supply control unit 63 calculates the current command value I to be supplied to the motor 21 via the current sensor 64 installed in the power supply line to the motor 21. m The test is performed. The power-on control unit 63 receives the current command value and the current I. m The deviation between the actual value and the control of the power supplied to motor 21 is minimized (for current I). m (Feedback control). Therefore, motor 21 controls according to the auxiliary command value T. * Generate torque.

[0032] Next, the instruction value calculation unit 62 will be described in detail. For example... Figure 3 As shown, the command value calculation unit 62 includes an adder 70, a target steering torque calculation unit 71, a torque feedback control unit 72, a target angle calculation unit 73, an angle feedback control unit 74, and an adder 75.

[0033] Adder 70 uses the steering torque T detected by torque sensor 51 to... h and the first auxiliary torque T1 calculated by the torque feedback control unit 72 * Add them together to calculate the input torque T in * This is the torque to be applied to the steering shaft 13.

[0034] The target steering torque calculation unit 71 is based on the input torque T calculated by the adder 70.in * To calculate steering torque T h * Target steering torque T h * To apply the steering torque T to the steering wheel 11 h The target value. The target steering torque calculation unit 71 calculates the value as the input torque T increases. in * The steering torque T has a larger absolute value as the absolute value increases. h * .

[0035] The torque feedback control unit 72 acquires the steering torque T detected by the torque sensor 51. h and the target steering torque T calculated by the target steering torque calculation unit 71 h * The torque feedback control unit 72 controls the steering torque T. h Execute feedback control to adjust the steering torque T detected by torque sensor 51. h Following the target steering torque T h * To calculate the first auxiliary torque T1 * .

[0036] The target angle calculation unit 73 acquires the steering torque T detected by the torque sensor 51. h The first auxiliary torque T1 calculated by the torque feedback control unit 72 * And the vehicle speed V detected by vehicle speed sensor 52. Target angle calculation unit 73 calculates the target angle based on the acquired steering torque T. h First auxiliary torque T1 * Calculate the target pinion angle θ based on vehicle speed V. p * Target pinion angle θ p * It is the target value of the rotation angle of the pinion shaft 23.

[0037] When the additional angle command value is calculated as the command value θ by the autonomous driving control function executed by the main control unit 500, * At that time, the instruction value θ * Added to the target pinion angle θ calculated by the target angle calculation unit 73 p * The instruction value θ has already been added. * The final target is the pinion angle θ. p * Provided to the angle feedback control unit 74.

[0038] The angle feedback control unit 74 acquires the target pinion angle θ p * calculated by the target angle calculation unit 73 p and the actual pinion angle θ p calculated by the pinion angle calculation unit 61 p . The angle feedback control unit 74 performs feedback control to make the actual pinion angle θ p follow the target pinion angle θ * . * .

[0039] The adder 75 calculates an assist command value T * by adding the first assist torque T * calculated by the torque feedback control unit 72 * and the second assist torque T * calculated by the angle feedback control unit 74 * . When a current based on the assist command value T pe is supplied to the motor 21, the motor 21 generates a torque according to the assist command value T p .

[0040] Next, the angle feedback control unit 74 will be described in detail. As shown in Figure 4 , the angle feedback control unit 74 includes a feedback control unit 81, a feedforward control unit 82, a disturbance observer 83, and an adder 84.

[0041] The feedback control unit 81 is configured to make a pinion angle estimation value θ * approach the target pinion angle θ pe . The pinion angle estimation value θ p is an estimated value of the pinion angle θ p calculated by the disturbance observer 83. The feedback control unit 81 includes a subtracter 81A and a PD control unit (proportional plus derivative control unit) 81B. The subtracter 81A calculates a deviation Δθ * (= θ pe - θ p ) between the target pinion angle θ p * calculated by the target angle calculation unit 73 and the pinion angle estimation value θ pe calculated by the disturbance observer 83. The PD control unit 81B calculates a feedback control torque T p by performing a proportional plus derivative operation on the deviation Δθ fb calculated by the subtracter 81A. In other words, the feedback control torque T fb is a torque for reducing the deviation Δθ pthe sum of the output value of the proportional control element and the output value of the differential control element of the input.

[0042] The feedforward control unit 82 is provided to improve the response of the control by compensating for a delay in the response due to the inertia of the EPS 10. The feedforward control unit 82 includes an angular acceleration calculation unit 82A and a multiplication unit 82B. The angular acceleration calculation unit 82A calculates a target pinion acceleration a (= d p * / dt 2 ) by evaluating the second derivative of the target pinion angle Q p * / dt 2 ). The multiplication unit 82B calculates a feedforward control torque T ff (= J · a) as an inertia compensation value by multiplying the inertia J of the EPS 10 by the target pinion acceleration a calculated by the angular acceleration calculation unit 82A. The inertia J is obtained, for example, from a physical model of the EPS 10.

[0043] The disturbance observer 83 is provided to estimate and compensate for a disturbance torque. The disturbance torque is a nonlinear torque that occurs as a disturbance in the actual device (EPS 10) to be actually controlled, and the disturbance torque is a torque that affects the pinion angle Q p in addition to the torque to be generated by the motor 21. The disturbance observer 83 calculates a disturbance torque estimate value T * as a disturbance torque compensation value and a pinion angle estimate value Q p based on the second auxiliary torque T2 ld and the actual pinion angle Q pe . The second auxiliary torque T2 * is a target value of the device. The actual pinion angle Q p is an output of the device.

[0044] The disturbance observer 83 calculates the disturbance torque estimate value T ld by multiplying a predetermined observer gain by the value of the difference between the pinion angle Q p calculated by the pinion angle calculation unit 61 and the pinion angle estimate value Q p (which will be described later) that is an estimate value of the pinion angle Q pe . The disturbance observer 83 calculates the pinion angle estimate value Q pe by multiplying the inverse of the inertia of the EPS 10 by the value obtained by adding the disturbance torque estimate value T ld to the second auxiliary torque T2 * calculated by the adder 84 and evaluating the second integral of the multiplication result. The disturbance observer 83 can be configured to use an auxiliary command value T* Replaces the second auxiliary torque T2 * To calculate the estimated value of the disturbance torque T ld And the estimated value of the pinion angle θ pe .

[0045] Adder 84 controls the input by feeding forward the torque T. ff With feedback control torque T fb Subtract the estimated disturbance torque T from the summed values ld To calculate the second auxiliary torque T2 * (=T fb +T ff -T ld Therefore, a second auxiliary torque T2 is obtained that compensates for the inertial torque and the disturbance torque. * Using the second auxiliary torque T2 * Auxiliary instruction value T * Therefore, it enables higher precision motor control.

[0046] The disturbance observer 83 estimates the disturbance torque based on a nominal device modeled as the actual device (EPS 10) to be controlled. For example... Figure 5 As shown, in a vehicle device that houses the actual equipment, a steering wheel 11 is coupled to a steering shaft 13. The steering shaft 13 includes an input shaft 13a, an output shaft 13b, and a torsion bar 13c. The input shaft 13a is coupled to the steering wheel 11. The output shaft 13b is coupled to the wheel steering shaft 15 via a pinion shaft 14. The torsion bar 13c couples the input shaft 13a and the output shaft 13b. A torque sensor 51 detects the torque applied to the steering shaft 13 based on the amount of torsion in the torsion bar 13c located at the center of the steering shaft 13.

[0047] The nominal device includes the portion of the steering shaft 13 downstream of the torsion bar 13c (i.e., the output shaft 13b), the pinion shaft 14, and the wheel steering shaft 15. Therefore, the inertia (nominal inertia) in the nominal device is the inertia of the output shaft 13b, the pinion shaft 14, and the wheel steering shaft 15—that is, the portion downstream of the torsion bar 13c. For this reason, when observed from the interference observer 83, the torque caused by the inertia of the steering wheel 11, which is the portion upstream of the torsion bar 13c, is the interference. The interference observer 83 essentially compensates for the inertial torque detected by the torque sensor 51 as interference.

[0048] However, the following problem exists when autonomous driving control is in operation. When autonomous driving control is in operation, the entity operating the steering wheel 11 is not the driver, but the control device used for autonomous driving control. For this reason, it is conceivable that the driver is not actively operating the steering wheel 11, but rather driving the vehicle in a hands-free state. In this hands-free state, the inertia of the steering wheel 11 can sometimes be significant.

[0049] For example, when the vibration frequency of the steering wheel 11 reaches a specific frequency range, resonance occurs due to the inertia of the steering wheel 11. As a result of this resonance, the difference between the frequency characteristics of the vehicle equipment including the steering wheel 11 and the nominal frequency characteristics of the interference observer 83 excluding the steering wheel 11 further increases. For this reason, the interference observer 83 may not be able to compensate for the inertial torque of the steering wheel 11 as an interference torque. Therefore, there exists an actual pinion angle θ. p Angle θ of the target pinion p * The problem of reduced tracking performance.

[0050] In this embodiment, in order to eliminate the resonance caused by the inertia of the steering wheel 11 when the steering wheel is released, the following configuration is used as the angle feedback control unit 74.

[0051] like Figure 4 As shown, the angle feedback control unit 74 includes a subtractor 85. The subtractor 85 acquires the steering torque T detected by the torque sensor 51. h and the second auxiliary torque T2 calculated by adder 84 * Subtractor 85 uses the second auxiliary torque T2 calculated by adder 84. * Subtract steering torque T from the middle h To calculate the final second auxiliary torque T2 used to control motor 21 * .

[0052] Therefore, according to this embodiment, the following operations and advantageous effects are obtained. When autonomous driving control is being performed, the torque sensor 51 detects the steering torque T while the vehicle is in a hands-free state. h The inertial torque of the steering wheel 11. The second auxiliary torque T2 calculated by adder 84. * Subtract the steering torque T, which is the inertial torque of the steering wheel 11. h The steering torque T h The interference observer 83 cannot adequately compensate for the inertial torque. Therefore, the final second auxiliary torque T2, which has already been compensated for, is obtained. * Based on the final second auxiliary torque T2 * By using the auxiliary instruction value T* By controlling motor 21, the actual pinion angle θ is ensured. p Angle θ of the target pinion p * This improves the vehicle's tracking performance and, as an extension, ensures vehicle responsiveness. In other words, it eliminates the resonance caused by the inertia of the steering wheel 11 when the steering wheel is released.

[0053] Other implementation methods

[0054] The above implementation can be modified as follows. The control device 50 can be applied to the EPS that applies auxiliary force to the steering shaft 13, instead of the EPS 10 that applies auxiliary force to the wheel steering shaft 15. In this case, as by Figure 1 The alternating long and short dashed lines indicate that motor 21 is coupled to steering shaft 13, for example, via reduction gear 22. Pinion shaft 23 can be omitted. In this case, main control unit 500 can calculate steering angle θ. s The target value (to be added to the current steering angle θ) s The angle θ is used as the command value for keeping the vehicle within the target lane when the autonomous driving control function is activated. * Steering angle θ s The rotation angle θ of the motor 21, which rotates in conjunction with the steering shaft 13, can be used as a reference. m To calculate.

[0055] When the interference observer 83 uses integration to calculate the pinion angle estimate θ pe In some cases, the interference estimation performance of the interference observer 83 may be reduced due to discretization errors in the high-frequency range. In such cases, the bilinear transform relation can be used for discrete integral operations.

[0056] The feedforward control unit 82 can be omitted from the angle feedback control unit 74. The angle feedback control unit 74 can be configured to take the estimated disturbance torque T calculated by the disturbance observer 83. ld Subtract steering torque T from the middle h Steering torque T h This refers to the inertial torque of steering wheel 11. Using the same configuration, a second auxiliary torque T2, which has already compensated for the inertial torque, is obtained. * The interference torque estimate T is calculated from the interference observer 83. ld Subtracting the inertial torque of steering wheel 11 from the value of the inertial torque, we obtain the estimated value of the disturbance torque T that is compensated for by the inertial torque of steering wheel 11. ld For this reason, the estimated value T of the disturbance torque is obtained. ld Corrected feedback control torque T fb, and as an extension, the feedback control torque T fb that has compensated for the inertia torque of the steering wheel 11 is obtained * . Thus, the influence of the torque due to the inertia of the steering wheel 11 is suppressed.

[0057] The following configuration can be employed as the command value calculation unit 62. The command value calculation unit 62 includes a calculation unit that, instead of the target steering torque calculation unit 71 and the torque feedback control unit 72 shown in FIG. 6, calculates a first assist torque T1 Figure 3 based on the steering torque T h and the vehicle speed V * . The calculation unit calculates the first assist torque T1 h by using, for example, a three-dimensional map that defines the relationship between the steering torque T * and the first assist torque T1 h instead of performing feedback control on the steering torque T * .

[0058] During autonomous driving control performed by the main control device 500, the command value calculation unit 62 can use the target pinion angle θ p * for autonomous driving calculated by the main control device 500 and the selected target pinion angle θ p * from among the target angles calculated by the target angle calculation unit 73 p * . The target pinion angle θ p * for autonomous driving is not an angle to be added to the current pinion angle θ p , but is an ideal angle according to the running state of the vehicle.

[0059] The adder 75 shown in FIG. 6 can be omitted from the command value calculation unit 62 Figure 3 . In this case, the second assist torque T2 * calculated by the angle feedback control unit 74 is used as the assist command value T * .

[0060] Other Technical Ideas

[0061] Next, the technical ideas that can be obtained according to the embodiments will be described below. A motor is used to generate an assist force that is a force for assisting in operating a steering wheel.

Claims

1. A steering control device (50) that controls an electric motor (21) for turning a steering wheel (12) of a vehicle in conjunction with a steering wheel (11) based on a command value calculated from a target angle that can be converted into an angle of a wheel turning angle of the steering wheel (12), the target angle being determined by a main control device on board, characterized by comprising an electronic control unit, wherein: the electronic control unit is configured to calculate a feedback control torque to be reflected in the command value by executing feedback control that is control to follow a predetermined angle that can be converted into the wheel turning angle and that is detected by a first sensor, to calculate a disturbance torque that is a torque that affects the predetermined angle and that is different from a torque to be generated by the electric motor (21) based on the calculated feedback control torque and the predetermined angle, to correct the calculated feedback control torque by using the calculated disturbance torque, to correct the command value that reflects the corrected feedback control torque based on an applied torque that is a torque to be applied to the steering wheel (11) and that is detected by a second sensor when an entity that is operating the steering wheel (11) is not a driver when autonomous driving control is being executed, and to subtract the applied torque from the command value that reflects the corrected feedback control torque.

2. A steering control device (50) that controls an electric motor (21) for turning a steering wheel (12) of a vehicle in conjunction with a steering wheel (11) based on a command value calculated from a target angle that can be converted into an angle of a wheel turning angle of the steering wheel (12), the target angle being determined by a main control device on board, characterized by comprising an electronic control unit, wherein: the electronic control unit is configured to calculate a feedback control torque to be reflected in the command value by executing feedback control that is control to follow a predetermined angle that can be converted into the wheel turning angle and that is detected by a first sensor, to calculate a disturbance torque that is a torque that affects the predetermined angle and that is different from a torque to be generated by the electric motor (21) based on the calculated feedback control torque and the predetermined angle, to correct the calculated feedback control torque by using the calculated disturbance torque, ​ ​ ​ ​ ​ ​ ​ ​ the electronic control unit is configured to correct the command value reflecting the corrected feedback control torque on the basis of an applied torque, which is a torque to be applied to the steering wheel (11) and detected by a second sensor when an entity operating the steering wheel (11) is not a driver while autonomous driving control is being executed; and the electronic control unit is configured to subtract the applied torque from the calculated disturbance torque.

3. The steering control device (50) according to claim 1 or 2, characterized in that: the electronic control unit is configured to calculate a feedforward control torque on the basis of a second-order time derivative of the target angle; and the electronic control unit is configured to subtract the disturbance torque from a value obtained by adding the feedforward control torque and the feedback control torque.

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