Steering control device and steering control method

Abstract

A steering control device (70) is configured to perform torque control processing, feedback amount calculation processing, and automatic control calculation processing. The torque control processing is processing that controls the torque of a motor in accordance with the value of a request torque variable. The request torque variable is a variable that indicates a target value for the torque of the motor. The feedback amount calculation processing is processing that calculates the value of the request torque variable in order to control steering torque to a target steering torque by feedback control.

Description

[Technical Field]

[0001] The present disclosure relates to a steering control device and a steering control method. [Background technology]

[0002] For example, Patent Document 1 listed below describes a control device that performs feedback control to control the steering torque, which is the torque applied to the steering wheel, to a target value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-223832 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the case of the above-mentioned device, it is not possible to optimize the behavior of the steering wheel when the driver is not operating the steering wheel. [Means for solving the problem]

[0005] One aspect of the present disclosure provides a steering control device configured to operate a motor mechanically coupled to an operating member operated by a driver to steer a vehicle, the steering control device being configured to execute a torque control process, a feedback amount calculation process, and an automatic control calculation process, the torque control process controlling the torque of the motor in accordance with a value of a required torque variable, the required torque variable being a variable indicating the torque of the motor, the feedback amount calculation process calculating a value of the required torque variable to control the steering torque to a target steering torque by feedback control, the steering torque being a torque input to the operating member, and the automatic control calculation process calculating a value of the required torque variable for displacing the operating member separately from operation of the operating member by the driver.

[0006] Another aspect of the present disclosure provides a steering control method for operating a motor mechanically coupled to an operating member operated by a driver to steer a vehicle, the steering control method including: executing a torque control process, executing a feedback amount calculation process, and executing an automatic control calculation process, wherein the torque control process controls the torque of the motor in accordance with a value of a required torque variable, the required torque variable being a variable indicating the torque of the motor, the feedback amount calculation process calculates a value of the required torque variable to control the steering torque to a target steering torque by feedback control, the steering torque being a torque input to the operating member, and the automatic control calculation process calculates a value of the required torque variable for displacing the operating member independently of operation of the operating member by the driver. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram showing the configuration of a steering system and a control device according to a first embodiment. [Figure 2] 2 is a block diagram showing a process executed by a control device shown in FIG. 1. FIG. [Figure 3]FIG. 10 is a block diagram showing a process executed by a control device according to a second embodiment. [Figure 4] FIG. 10 is a block diagram showing a process executed by a control device according to a third embodiment. [Figure 5] FIG. 10 is a block diagram showing a process executed by a control device according to a fourth embodiment. [Figure 6] FIG. 11 is a block diagram showing a process executed by a control device according to a fifth embodiment. [Figure 7] FIG. 13 is a block diagram showing a process executed by a control device according to a sixth embodiment. [Figure 8] FIG. 13 is a block diagram showing a process executed by a control device according to a seventh embodiment. [Figure 9] FIG. 13 is a block diagram showing a process executed by a control device according to an eighth embodiment. [Figure 10] FIG. 13 is a block diagram showing a process executed by a control device according to a ninth embodiment. [Figure 11] FIG. 20 is a block diagram showing a process executed by a control device according to a tenth embodiment. [Figure 12] FIG. 22 is a block diagram showing a process executed by a control device according to an eleventh embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] First Embodiment A first embodiment of the steering control device will be described below with reference to the drawings. "Prerequisite configuration" As shown in Fig. 1, a vehicle steering system 10 includes a reaction force actuator Ar and a turning actuator At. The steering system 10 of this embodiment has a structure in which the power transmission path between the steering wheel 12 and the steered wheels 44 is mechanically disconnected. In other words, the steering system 10 includes a steer-by-wire type steering device.

[0009] A steering shaft 14 is connected to the steering wheel 12. The reaction force actuator Ar is an actuator for applying a steering reaction force to the steering wheel 12. The steering reaction force is a force that acts in the opposite direction to the direction of operation of the steering wheel 12 by the driver. By applying the steering reaction force to the steering wheel 12, it is possible to give the driver an appropriate sense of responsiveness. The reaction force actuator Ar includes a reduction mechanism 16, a reaction force motor 20, and a reaction force inverter 22.

[0010] The reaction motor 20 is a three-phase brushless motor. The rotating shaft of the reaction motor 20 is connected to the steering shaft 14 via a reduction gear mechanism 16. The reaction inverter 22 is a power conversion circuit that converts the voltage of a battery 24, which is a DC voltage source, into AC voltage and applies it to the reaction motor 20.

[0011] Meanwhile, steering shaft 40 extends along the vehicle width direction, which is the left-right direction in Figure 1. Left and right steered wheels 44 are connected to both ends of steering shaft 40 via tie rods 42. The linear movement of steering shaft 40 changes the steering angle of steered wheels 44.

[0012] Steering actuator At includes speed reduction mechanism 56, steering motor 60, and steering inverter 62. Steering motor 60 is a three-phase brushless motor. The rotating shaft of steering motor 60 is connected to pinion shaft 52 via speed reduction mechanism 56. Pinion teeth of pinion shaft 52 mesh with rack teeth 54 of steering shaft 40. A rack-and-pinion mechanism is formed by pinion shaft 52 and steering shaft 40 provided with rack teeth 54. The torque of steering motor 60 is applied as a steering force to steering shaft 40 via pinion shaft 52. In response to the rotation of steering motor 60, steering shaft 40 moves along the vehicle width direction, which is the left-right direction in FIG. 1 .

[0013] The steering system 10 includes a control device 70 . The control device of the control device 70 is the steering device. More specifically, the control device of the control device 70 is the steering wheel 12 of the steering device. The control device 70 operates a reaction force actuator Ar to control the steering reaction force, which is the control variable of the control device. Fig. 1 shows an operation signal MSs to the reaction force inverter 22. The control device 70 also controls the steered wheels 44 of the steering device. The control device 70 operates a steering actuator At to control the steering angle of the steered wheels 44, which is the control variable of the control device. Fig. 1 shows an operation signal MSt to the steering inverter 62.

[0014] In order to control the controlled variable, control device 70 refers to steering torque Th, which is input torque to steering shaft 14, detected by torque sensor 80. Torque sensor 80 includes a torsion bar connected to steering shaft 14 and a sensing element that detects the torsion angle of the torsion bar. Control device 70 also refers to rotation angle θa of the rotary shaft of reaction force motor 20, detected by rotation angle sensor 82. Control device 70 also refers to currents iu1, iv1, iw1 that flow through reaction force motor 20. Currents iu1, iv1, iw1 are quantified as voltage drops across shunt resistors provided in each leg of reaction force inverter 22. Control device 70 also refers to rotation angle θb of the rotary shaft of turning motor 60, detected by rotation angle sensor 84, in order to control the controlled variable. Control device 70 also refers to currents iu2, iv2, iw2 that flow through turning motor 60. The currents iu2, iv2, and iw2 are quantified as the amount of voltage drop across a shunt resistor provided in each leg of the steering inverter 62. The control device 70 also refers to the yaw rate yr detected by the yaw rate sensor 90. The control device 70 also refers to the vehicle speed V detected by the vehicle speed sensor 92.

[0015] The control device 70 includes a PU 72, a storage device 74, and peripheral circuits 76. The PU 72 is a software processing device such as a CPU, a GPU, and a TPU. The storage device 74 includes a storage medium such as an electrically rewritable nonvolatile memory and a disk medium. A steering control program 74a is stored in the storage device 74. The peripheral circuits 76 include a circuit that generates a clock signal that regulates internal operations, a power supply circuit, a reset circuit, and the like. The control device 70 controls the control amount by having the PU 72 execute the steering control program 74a stored in the storage device 74.

[0016] "control" FIG. 2 shows part of the processing executed by the control device 70. The steering angle calculation process M10 is a process that uses the rotation angle θa as an input and calculates the steering angle θh, which is the rotation angle of the steering wheel 12. The steering angle calculation process M10 includes a process that converts the rotation angle θa into an integrated angle that includes a range exceeding 360°, for example, by counting the number of rotations of the reaction force motor 20 from a steering neutral position, which is the position of the steering wheel 12 when the vehicle is traveling straight. The steering angle calculation process M10 includes a process that calculates the steering angle θh by multiplying the integrated angle obtained by conversion by a conversion coefficient based on the rotational speed ratio of the speed reduction mechanism 16. Note that the steering angle θh is positive when it is an angle to the right of the steering neutral position, and negative when it is an angle to the left of the steering neutral position, for example.

[0017] Pinion angle calculation process M12 is a process that uses rotation angle θb as an input and calculates pinion angle θp, which is the rotation angle of pinion shaft 52. Pinion angle calculation process M12 includes, for example, a process of counting the number of rotations of steering motor 60 from a rack neutral position, which is the position of steering shaft 40 when the vehicle is traveling straight, and converting the counted number of rotations into an integrated angle that includes a range exceeding 360°. Pinion angle calculation process M12 includes a process of multiplying the converted integrated angle by a conversion coefficient based on the rotational speed ratio of speed reduction mechanism 56 to calculate pinion angle θp, which is the actual rotation angle of pinion shaft 52. Note that pinion angle θp is positive when it is an angle to the right of the rack neutral position, and negative when it is an angle to the left of the rack neutral position, for example. Steering motor 60 and pinion shaft 52 are linked via speed reduction mechanism 56. Therefore, there is a one-to-one correspondence between the integrated value of rotation angle θb of steering motor 60 and pinion angle θp. Using this correspondence, pinion angle θp can be found from rotation angle θb of steering motor 60. Furthermore, pinion shaft 52 is meshed with steered shaft 40. Therefore, there is also a one-to-one correspondence between pinion angle θp and the amount of movement of steered shaft 40. Therefore, there is also a one-to-one correspondence between pinion angle θp and the steering angle of steered wheels 44.

[0018] The target pinion angle calculation process M14 is a process that calculates a target pinion angle θp* using the steering angle θh and the vehicle speed V as inputs. The target pinion angle θp* is a target value of the pinion angle θp according to the operation of the steering wheel 12 by the driver. The target pinion angle calculation process M14 includes a process that variably sets the steering angle ratio Dr according to the vehicle speed V. Therefore, the target pinion angle θp* output by the target pinion angle calculation process M14 will be a different value depending on the vehicle speed V even if the input steering angle θh is the same.

[0019] The pinion angle feedback process M16 is a process for calculating a steering torque command value Tt*, which is a command value for the torque of the steering motor 60, in order to control the pinion angle θp to the target pinion angle θp* by feedback control.

[0020] The steering operation process M18 is a process that receives as input the steering torque command value Tt*, currents iu2, iv2, iw2, and rotation angle θb, and outputs an operation signal MSt for the steering inverter 62. The steering operation process M18 includes a process that calculates current command values ​​for the dq axes based on the steering torque command value Tt*. The steering operation process M18 also includes a process that calculates currents for the dq axes based on the currents iu2, iv2, iw2 and the rotation angle θb. The steering operation process M18 then includes a process that calculates an operation signal MSt for operating the steering inverter 62 so that the currents for the dq axes become the command values.

[0021] The axial force calculation process M19 includes a process of calculating the axial force Taf using the turning torque command value Tt* as an input. Here, the axial force Taf is the force applied to the turning shaft 40 in the axial direction. The base target torque calculation process M20 is a process for calculating a base target torque Thb*, which is a base value of a target steering torque Th* that the driver should input to the steering shaft 14 via the steering wheel 12, based on the axial force Taf. Here, the axial force Taf is an axial force applied to the steered shaft 40. The axial force Taf is an amount that depends on the lateral force acting on the steered wheels 44, and therefore the lateral force can be determined from the axial force Taf. On the other hand, it is desirable to determine the torque that the driver should input to the steering shaft 14 via the steering wheel 12 depending on the lateral force. Therefore, the base target torque calculation process M20 is a process for calculating the base target torque Thb* depending on the lateral force determined from the axial force Taf.

[0022] Specifically, the base target torque calculation process M20 includes a process for variably setting the absolute value of the base target torque Thb* in accordance with the absolute value of the axial force Taf. This process may be a process for calculating the absolute value of the base target torque Thb* when the vehicle speed V is small to be equal to or less than the absolute value of the base target torque Thb* when the vehicle speed V is large, even if the absolute value of the axial force Taf is the same. This can be realized, for example, by having the PU 72 calculate the base target torque Thb* using a map while map data is pre-stored in the storage device 74. This map data is data in which the axial force Taf or the lateral acceleration and vehicle speed V determined from the axial force Taf are used as input variables, and the base target torque Thb* is used as an output variable.

[0023] Map data is a set of data consisting of discrete values ​​of input variables and values ​​of output variables corresponding to each of the input variable values. Furthermore, the map calculation may be a process in which, when the value of an input variable matches one of the input variable values ​​in the map data, the value of the corresponding output variable in the map data is used as the calculation result. Furthermore, when the value of an input variable does not match any of the input variable values ​​in the map data, the map calculation may be a process in which the value obtained by interpolating the values ​​of multiple output variables included in the map data is used as the calculation result. Alternatively, when the value of an input variable does not match any of the input variable values ​​in the map data, the map calculation may be a process in which the value of the output variable in the map data that corresponds to the closest value among the multiple output variable values ​​included in the map data is used as the calculation result.

[0024] The hysteresis processing M22 is a processing for calculating and outputting a hysteresis correction amount Thys for correcting the base target torque Thb* based on the steering angle θh. More specifically, the hysteresis processing M22 includes a processing for distinguishing between when the steering wheel 12 is being turned and when it is being turned back based on changes in the steering angle θh, etc., and calculating the hysteresis correction amount Thys. More specifically, the hysteresis processing M22 includes a processing for calculating the hysteresis correction amount Thys so that the absolute value of the target steering torque Th* is larger when the steering wheel 12 is being turned back than when it is being turned back. The hysteresis processing M22 includes a processing for variably setting the hysteresis correction amount Thys according to the vehicle speed V.

[0025] The addition process M24 is a process for calculating the target steering torque Th* by adding the hysteresis correction amount Thys to the base target torque Thb*. The feedback amount calculation process M26 is a process for calculating a target reaction force Ts1* corresponding to the steering reaction force to be applied to the steering wheel 12, which is an operation amount required to control the steering torque Th to the target steering torque Th* by feedback control. The target reaction force Ts1* is actually a command value for the reaction force motor 20. The value obtained by multiplying the target reaction force Ts1* by a coefficient corresponding to the reduction ratio of the reduction mechanism 16 becomes the steering reaction force.

[0026] The linear operator M40 is a process for calculating the first-order time differential value of the rotation angle θa and substituting it for the steering angular velocity ωh. The damping process M42 is a process for calculating the target reaction force Ts2* in accordance with the steering angular velocity ωh and the vehicle speed V. The damping process M42 may be a process in which the PU 72 calculates the target reaction force Ts* from a map in a state in which map data is stored in the storage device 74. Here, the map data is data in which the steering angular velocity ωh and the vehicle speed V are input variables and the target reaction force Ts2* is an output variable.

[0027] The composite value calculation process M30 is a process for calculating the target reaction force Ts* by subtracting the target reaction force Ts2* from the target reaction force Ts1*. The reaction force operation process M32 is a process that receives the target reaction force Ts*, currents iu1, iv1, iw1, and rotation angle θa as inputs and outputs an operation signal MSs for the reaction force inverter 22. The reaction force operation process M32 includes a process of calculating dq-axis current command values ​​based on the target reaction force Ts*. The reaction force operation process M32 also includes a process of calculating dq-axis currents based on the currents iu1, iv1, iw1 and the rotation angle θa. The reaction force operation process M32 then includes a process of calculating an operation signal MSs for operating the reaction force inverter 22 so that the dq-axis currents become command values.

[0028] <Actions and Effects of This Embodiment> The PU 72 determines the target reaction force Ts* by subtracting the target reaction force Ts2* from the target reaction force Ts1*. The PU 72 then controls the torque of the reaction force motor 20 to the target reaction force Ts*. Here, the target reaction force Ts1* is an operation amount for controlling the steering torque Th to the target steering torque Th* by feedback control. If the driver releases his / her hands from the steering wheel 12, for example, it is not possible to apply a reaction force to the driver via the steering wheel 12 in the first place, and therefore the target reaction force Ts1* is not necessarily an appropriate value as the torque to be applied to the steering wheel 12.

[0029] Therefore, the PU 72 sets the target reaction force Ts* to a value obtained by subtracting the target reaction force Ts2* output by the damping process M42 from the target reaction force Ts1* output by the feedback amount calculation process M26. Therefore, even if the target reaction force Ts1* becomes an inappropriate value for the torque to be applied to the steering wheel 12 due to the driver releasing his / her hands from the steering wheel 12, the rotation speed of the steering wheel 12 is corrected by the target reaction force Ts2*. In other words, when the steering wheel 12 is displaced in accordance with the target reaction force Ts1*, the PU 72 sets the target reaction force Ts* to a value obtained by subtracting the target reaction force Ts2* corresponding to the steering angular velocity ωh from the target reaction force Ts1*. This makes it possible to maintain appropriate steering wheel behavior even when the driver releases his / her hands from the steering wheel.

[0030] According to the present embodiment described above, the following further functions and effects can be obtained. (1-1) The PU 72 calculates the base target torque Thb* in accordance with the vehicle speed V. That is, the PU 72 calculates the target steering torque Th* in accordance with the vehicle speed V. On the other hand, the PU 72 calculates the target reaction force Ts2* in accordance with the vehicle speed V. Therefore, the target reaction force Ts2* can be set to an appropriate value in accordance with the vehicle speed V, which is a variable used in calculating the target steering torque Th*.

[0031] (1-2) The PU 72 operates the reaction force motor 20 while the power transmission between the steering wheel 12 and the steered wheels 44 is cut off. In this case, since no load on the steered wheels 44 side is applied to the steering wheel 12, when the driver releases his / her hands from the steering wheel 12, the torque of the reaction force motor 20 significantly affects the behavior of the steering wheel 12. Therefore, the usefulness of the target reaction force Ts2* is particularly great.

[0032] Second Embodiment The second embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment.

[0033] Fig. 3 shows part of the processing executed by the control device 70. In Fig. 3, the processing corresponding to the processing shown in Fig. 2 is denoted by the same reference numerals for convenience. The target steering angular velocity calculation process M44 is a process for calculating the target steering angular velocity ωh* according to the magnitude of the steering angle θh and the vehicle speed V. The target steering angular velocity calculation process M44 may be, for example, a process for setting the magnitude of the target steering angular velocity ωh* when the magnitude of the steering angle θh is large to be equal to or greater than the magnitude of the target steering angular velocity ωh* when the magnitude of the steering angle θh is small. In this case, there exist a first angle θh1 of the steering angle θh and a second angle θh2 smaller than the first angle θh1, for which the following relationship holds:

[0034] The magnitude of the target steering angular velocity ωh* when the steering angle θh is the first angle θh1 is greater than the magnitude of the target steering angular velocity ωh* when the steering angle θh is the second angle θh2. Further, for example, the target steering angular velocity calculation process M44 may be a process that sets the magnitude of the target steering angular velocity ωh* when the vehicle speed V is high to be equal to or greater than the magnitude of the target steering angular velocity ωh* when the vehicle speed V is low. In this case, for the vehicle speed V, a first speed V1 and a second speed V2 that is lower than the first speed V1 satisfy the following relationship:

[0035] The magnitude of the target steering angular velocity ωh* when the vehicle speed V is the first speed V1 is greater than the magnitude of the target steering angular velocity ωh* when the vehicle speed V is the second speed V2. The target steering angular velocity calculation process M44 may be, for example, a process in which the PU 72 calculates the target steering angular velocity ωh* using a map while map data is stored in the storage device 74. Here, the map data is a process in which the magnitude of the steering angle θh and the vehicle speed V are used as input variables, and the target steering angular velocity ωh* is used as an output variable.

[0036] The steering angular velocity feedback process M48 is a process of substituting, for the target reaction force Ts2*, a manipulated variable for controlling the steering angular velocity ωh to the target steering angular velocity ωh* by feedback control. The steering angular velocity feedback process M48 may, for example, be a process of substituting, for the target reaction force Ts2*, the output value of a proportional element having as its input the difference between the steering angular velocity ωh and the target steering angular velocity ωh*. Alternatively, for example, the steering angular velocity feedback process M48 may be a process of substituting, for the target reaction force Ts2*, the sum of the output value of the proportional element and the output value of a derivative element of the difference. Alternatively, for example, the steering angular velocity feedback process M48 may be a process of substituting, for the target reaction force Ts2*, the sum of the output value of the proportional element, the output value of the derivative element, and the output value of an integral element of the difference. Alternatively, for example, the steering angular velocity feedback process M48 may be a process of substituting, for the target reaction force Ts2*, the sum of the output value of the proportional element and the output value of the integral element.

[0037] The composite value calculation process M30a is a process of substituting a value obtained by adding the target reaction force Ts2* to the target reaction force Ts1* for the target reaction force Ts*. <Actions and Effects of Second Embodiment> The PU 72 substitutes the operation amount for controlling the steering angular velocity ωh to the target steering angular velocity ωh* by feedback control into the target reaction force Ts2*. Then, the PU 72 sets the sum of the target reaction force Ts1* and the target reaction force Ts2* as the target reaction force Ts*. As a result, even if the target reaction force Ts1* becomes an inappropriate value as the torque to be applied to the steering wheel 12 due to the driver releasing his / her hands from the steering wheel 12, the steering angular velocity ωh is controlled to the target steering angular velocity ωh*. As a result, the behavior of the steering wheel can be made appropriate even when the driver releases his / her hands from the steering wheel.

[0038] According to the present embodiment described above, the following further functions and effects can be obtained. (2-1) The PU 72 sets the target steering angular velocity ωh* in accordance with the value of the steering angle θh, thereby controlling the steering angular velocity ωh to an appropriate velocity in accordance with the steering angle θh.

[0039] (2-2) The PU 72 calculated the base target torque Thb* in accordance with the vehicle speed V. That is, the PU 72 calculated the target steering torque Th* in accordance with the vehicle speed V. On the other hand, the PU 72 calculated the target steering angular velocity ωh* in accordance with the vehicle speed V. That is, the PU 72 calculated the target reaction force Ts2* in accordance with the vehicle speed V. Therefore, the target reaction force Ts2* can be set to an appropriate value in accordance with the vehicle speed V, which is a variable used in calculating the target steering torque Th*.

[0040] <Third embodiment> The third embodiment will be described below with reference to the drawings, focusing on the differences from the first and second embodiments.

[0041] Fig. 4 shows part of the processing executed by the control device 70. In Fig. 4, the processing corresponding to the processing shown in Fig. 2 and Fig. 3 is denoted by the same reference numerals for convenience.

[0042] 4, in this embodiment, the output of the damping process M42 is set to the target reaction force Ts2a*, and the output of the steering angular velocity feedback process M48 is set to the target reaction force Ts2b*.

[0043] The synthesis process M49 is a process of substituting the value obtained by subtracting the target reaction force Ts2a* from the target reaction force Ts2b* for the target reaction force Ts2*. The composite value calculation process M30a is a process of substituting a value obtained by adding the target reaction force Ts2* to the target reaction force Ts1* for the target reaction force Ts*.

[0044] <Fourth embodiment> The fourth embodiment will be described below with reference to the drawings, focusing on the differences from the third embodiment.

[0045] Fig. 5 shows part of the processing executed by the control device 70. In Fig. 5, the processing corresponding to the processing shown in Fig. 4 is denoted by the same reference numerals for convenience. The target yaw rate calculation process M44a is a process for calculating the target yaw rate yr* in accordance with the magnitude of the steering angle θh and the vehicle speed V. The target yaw rate calculation process M44a may be, for example, a process in which the PU 72 calculates the target yaw rate yr* from a map in a state in which map data is stored in the storage device 74. Here, the map data is data in which the magnitude of the steering angle θh and the vehicle speed V are input variables and the target yaw rate yr* is an output variable.

[0046] The yaw rate feedback process M48a is a process of substituting, for the target reaction force Ts2b*, an operation amount for controlling the yaw rate yr to the target yaw rate yr* by feedback control. The yaw rate feedback process M48a may be, for example, a process of substituting, for the target reaction force Ts2b*, an output value of a proportional element having, as input, the difference between the yaw rate yr and the target yaw rate yr*. Alternatively, for example, the yaw rate feedback process M48a may be a process of substituting, for the target reaction force Ts2b*, the sum of the output value of the proportional element and the output value of a derivative element of the difference. Alternatively, for example, the yaw rate feedback process M48a may be a process of substituting, for the target reaction force Ts2b*, the sum of the output value of the proportional element, the output value of the derivative element, and the output value of an integral element of the difference. Alternatively, for example, the yaw rate feedback process M48a may be a process of substituting, for the target reaction force Ts2b*, the sum of the output value of the proportional element and the output value of the integral element.

[0047] Fifth Embodiment The fifth embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment.

[0048] Fig. 6 shows part of the processing executed by the control device 70. In Fig. 6, the processing corresponding to the processing shown in Fig. 2 is denoted by the same reference numerals for convenience. The target steering angle calculation process M50 is a process for calculating the target steering angle θh* using the axial force Taf as an input. The target steering angle calculation process M50 is a process for calculating the target steering angle θh* using a model formula expressed by the following formula (c1).

[0049] Taf=K·θh*+C·θh*'+J·θh*'' …(c1) The model expressed by the above formula (c1) is that the torque equal to the axial force Taf is applied to the steering. This model is a model of the value that the steering angle θh indicates when it is input to the steering shaft 14. This model is a model that assumes a virtual steering device in which the steering wheel 12 and the steered wheels are mechanically connected. In the above formula (c1), the viscosity coefficient C models the friction of the steering device, etc. In the above formula (c1), the inertia coefficient J models the inertia of the steering device. In the above formula (c1), the spring coefficient K models the specifications of the suspension, wheel alignment, etc. of the vehicle on which the steering device is installed.

[0050] The steering angle feedback process M52 is a process of substituting, for the target reaction force Ts2*, an operation amount for controlling the steering angle θh to the target steering angle θh* by feedback control. The steering angle feedback process M52 may be, for example, a process of substituting, for the target reaction force Ts2*, an output value of a proportional element having, as input, the difference between the steering angle θh and the target steering angle θh*. Alternatively, for example, the steering angle feedback process M52 may be a process of substituting, for the target reaction force Ts2*, the sum of the output value of the proportional element and the output value of a derivative element of the difference. Alternatively, for example, the steering angle feedback process M52 may be a process of substituting, for the target reaction force Ts2*, the sum of the output value of the proportional element, the output value of the derivative element, and the output value of an integral element of the difference. Alternatively, for example, the steering angle feedback process M52 may be a process of substituting, for the target reaction force Ts2*, the sum of the output value of the proportional element and the output value of the integral element.

[0051] The composite value calculation process M30a is a process of substituting the sum of the target reaction force Ts1* and the target reaction force Ts2* for the target reaction force Ts*. <Functions and Effects of Fifth Embodiment> The PU 72 substitutes the operation amount for controlling the steering angle θh to the target steering angle θh* by feedback control into the target reaction force Ts2*. Then, the PU 72 sets the sum of the target reaction force Ts1* and the target reaction force Ts2* as the target reaction force Ts*. As a result, even if the target reaction force Ts1* becomes an inappropriate value as the torque to be applied to the steering wheel 12 due to the driver releasing his / her hands from the steering wheel 12, the steering angle θh is controlled to the target steering angle θh*. As a result, the behavior of the steering wheel can be made appropriate even when the driver releases his / her hands from the steering wheel.

[0052] According to the present embodiment described above, the following further functions and effects can be obtained. (5-1) The PU 72 calculates the target steering angle θh* based on the above formula (c1). This allows the behavior of the steering wheel 12 to be adjusted by the viscosity coefficient C, the inertia coefficient J, and the spring coefficient K.

[0053] Sixth Embodiment The sixth embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment.

[0054] Fig. 7 shows part of the processing executed by the control device 70. In Fig. 7, the processing corresponding to the processing shown in Fig. 2 is denoted by the same reference numerals for convenience. The operation state estimation process M60 is a process that estimates whether the driver is operating the steering wheel 12 using the steering torque Th and the steering angle θh as inputs. The operation state estimation process M60 may be a process that estimates whether the driver is operating the steering wheel 12 based on, for example, a comparison between the steering torque Th and a threshold value. In this case, the threshold value may be set according to the steering angle θh. The operation state estimation process M60 may include a process that calculates a first-order time differential value of the steering angle θh. In this case, the operation state estimation process M60 is a process that estimates whether the driver is operating the steering wheel 12 by taking into account the operation angular velocity.

[0055] The switching process M62 is a process that receives the estimation result of the operation state estimation process M60 as input and selectively outputs one of the two inputs, target reaction force Ts1* and target reaction force Ts2*. The switching process M62 includes a process of substituting the target reaction force Ts1* for the target reaction force Ts*0 when it is estimated that the driver is operating the steering wheel 12. The switching process M62 includes a process of substituting the target reaction force Ts2* for the target reaction force Ts*0 when it is estimated that the driver is not operating the steering wheel 12.

[0056] The gradual change process M64 is a process for gradually changing the target reaction force Ts* when the target reaction force Ts*0, which is the output of the switching process M62, is switched from either the target reaction force Ts1* or the target reaction force Ts2* to the other. That is, the gradual change process M64 is a process for gradually changing the target reaction force Ts* from the target reaction force Ts1* to the target reaction force Ts2* when the output of the switching process M62 is switched from the target reaction force Ts1* to the target reaction force Ts2*. Furthermore, the gradual change process M64 is a process for gradually changing the target reaction force Ts* from the target reaction force Ts2* to the target reaction force Ts1* when the output of the switching process M62 is switched from the target reaction force Ts2* to the target reaction force Ts1*.

[0057] The gradual change process M64 variably sets the gradual change speed depending on the vehicle speed V and the steering angular velocity ωh. <Actions and Effects of the Sixth Embodiment> The PU 72 switches between using the target reaction force Ts1* and the target reaction force Ts2* depending on the estimation result of whether the driver is operating the steering wheel 12. As a result, when the driver is operating the steering wheel 12, the target reaction force Ts1* can be used as the torque command value for the reaction force motor 20. Therefore, the steering torque Th can be controlled to the target steering torque Th* with high accuracy. Furthermore, when the driver is not operating the steering wheel 12, the PU 72 can use the target reaction force Ts2* as the torque command value for the reaction force motor 20. Therefore, the damping process M42 can be a process that determines an appropriate target reaction force Ts2* on the assumption that the target reaction force Ts1* is not superimposed. Therefore, it is possible to achieve both the damping process M42 determining an appropriate target reaction force Ts2* and easy design of the damping process M42.

[0058] According to the present embodiment described above, the following further functions and effects can be obtained. (6-1) When the output of the switching process M62 is switched, the PU 72 gradually changes the target reaction force Ts* from the first value, which is the value before the switching, to the second value, which is the value after the switching, by the gradual change process M64. This makes it possible to prevent a sudden change in the target reaction force Ts*.

[0059] (6-2) The PU 72 estimates whether the driver is operating the steering wheel 12 by inputting not only the steering torque Th but also the steering angle θh. This improves the estimation accuracy compared to when estimation is made only from the steering torque Th.

[0060] Seventh Embodiment The seventh embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment.

[0061] Fig. 8 shows part of the processing executed by the control device 70. In Fig. 8, the processing corresponding to the processing shown in Fig. 2 is denoted by the same reference numerals for convenience. The contribution rate varying process M70 varies the contribution rates of the target reaction force Ts1* and the target reaction force Ts2* to the target reaction force Ts*. More specifically, the contribution rate calculation process M72 calculates the contribution rate R using the steering torque Th as an input. The contribution rate R takes a value between "0" and "1". The contribution rate R is a variable indicating the contribution rate of the target reaction force Ts2* to the target reaction force Ts*. The contribution rate calculation process M72 includes a process of setting the contribution rate R when the magnitude of the steering torque Th is large to be equal to or smaller than the contribution rate R when the magnitude of the steering torque Th is small. In particular, the contribution rate calculation process M72 includes a process of setting the contribution rate R to "0" when the magnitude of the steering torque Th is equal to or greater than a predetermined value. The contribution rate calculation process M72 may be a process of calculating the contribution rate R using a map by the PU 72 with map data stored in the storage device 74. Here, the map data is data using the steering torque Th as an input variable and the contribution rate R as an output variable.

[0062] Multiplication process M74 is a process for multiplying the target reaction force Ts2* by the contribution rate R. Second contribution rate calculation process M76 is a process for outputting "1-R", which is the value obtained by subtracting the contribution rate R from "1". "1-R" is the second contribution rate. The second contribution rate is a variable indicating the contribution rate of the target reaction force Ts1* to the target reaction force Ts*. Multiplication process M78 is a process for multiplying the target reaction force Ts1* by the contribution rate R. Addition process M79 is a process for substituting the sum of the output value of multiplication process M74 and the output value of multiplication process M78 for target reaction force Ts*.

[0063] As a result, the target reaction force Ts* is as follows: Ts*=(1-R) ​​Ts1*+R Ts2* <Actions and Effects of Seventh Embodiment> The PU 72 calculates the contribution ratios R, 1-R of the target reaction force Ts1* and the target reaction force Ts2* to the target reaction force Ts* according to the magnitude of the steering torque Th. Then, the PU 72 substitutes "(1-R)·Ts1*+R·Ts2*" for the target reaction force Ts*. As a result, when the torque applied by the driver to the steering wheel 12 is large, the torque of the reaction force motor 20 can be set to the target reaction force Ts1*. Therefore, the steering torque Th can be controlled to the target steering torque Th* with high accuracy. Furthermore, when the torque applied by the driver to the steering wheel 12 is small, the PU 72 can set the target reaction force Ts2* as the torque command value for the reaction force motor 20. Therefore, the damping process M42 can be a process that determines an appropriate target reaction force Ts2* on the assumption that the influence of the target reaction force Ts* is small. Therefore, it is possible to achieve both the damping process M42 determining an appropriate target reaction force Ts2* and facilitating the design of the damping process M42.

[0064] Eighth Embodiment The eighth embodiment will be described below with reference to the drawings, focusing on the differences from the sixth embodiment.

[0065] Fig. 9 shows part of the processing executed by the control device 70. In Fig. 9, the processing corresponding to the processing shown in Fig. 4 and Fig. 7 is denoted by the same reference numerals for convenience.

[0066] As shown in Fig. 9, in this embodiment, the target reaction force Ts2* is set to a value obtained by subtracting the target reaction force Ts2a* from the target reaction force Ts2b*, as in the process of Fig. 4. However, the PU 72 executes the operation state estimation process M60, the switching process M62, and the gradual change process M64, as shown in Fig. 7.

[0067] Ninth Embodiment The ninth embodiment will be described below with reference to the drawings, focusing on the differences from the sixth embodiment.

[0068] Fig. 10 shows part of the processing executed by the control device 70. In Fig. 10, the processing corresponding to the processing shown in Fig. 4 and Fig. 8 is denoted by the same reference numerals for convenience.

[0069] As shown in Fig. 10, in this embodiment, the target reaction force Ts2* is set to a value obtained by subtracting the target reaction force Ts2a* from the target reaction force Ts2b*, as in the process of Fig. 4. However, the PU 72 executes the contribution rate varying process M70 as shown in Fig. 8.

[0070] <Tenth embodiment> The tenth embodiment will be described below with reference to the drawings, focusing on the differences from the sixth embodiment.

[0071] Fig. 11 shows part of the processing executed by the control device 70. In Fig. 11, the processing corresponding to the processing shown in Fig. 6 and Fig. 7 is denoted by the same reference numerals for convenience.

[0072] As shown in Fig. 11, in this embodiment, the target reaction force Ts2* is set as the output value of the steering angle feedback process M52, similar to the process in Fig. 6. However, the PU 72 executes the operation state estimation process M60, the switching process M62, and the gradual change process M64, as shown in Fig. 7.

[0073] Eleventh Embodiment The eleventh embodiment will be described below with reference to the drawings, focusing on the differences from the sixth embodiment.

[0074] Fig. 12 shows part of the processing executed by the control device 70. In Fig. 12, the processing corresponding to the processing shown in Fig. 6 and Fig. 8 is denoted by the same reference numerals for convenience.

[0075] As shown in Fig. 12, in this embodiment, the target reaction force Ts2* is set as the output value of the steering angle feedback process M52, as in the process of Fig. 6. However, the PU 72 executes the contribution rate varying process M70 as shown in Fig. 8.

[0076] <Other embodiments> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0077] "About turning speed variables" The turning speed variable, which is a variable indicating the motor rotation speed or yaw rate, is not limited to the steering angular velocity ωh or the yaw rate yr. For example, it may be a first-order time differential value of the rotation angle θa. Furthermore, instead of calculating a first-order time differential value using the rotation angle θa, a detection value of a sensor that detects the rotation angular velocity may be used.

[0078] "About dumping processing" The damping process is not limited to a process that uses the value of the turning speed variable and the vehicle speed V as input. For example, the damping process may use the value of the turning speed variable as input, but not the vehicle speed V as input.

[0079] "About turning speed feedback processing" The turning velocity feedback process is not limited to the steering angular velocity feedback process M48 or the yaw rate feedback process M48a. For example, it may be a process in which a first-order time differential value of the turning angle θa is input and the time differential value is controlled to a target value through feedback control.

[0080] "Regarding the calculation process of target turning angular velocity variables" The target turning angular velocity variable calculation process does not necessarily require the vehicle speed V and steering angle θh as inputs. For example, the steering angle θh may be input, but the vehicle speed V may not be input.

[0081] "On the value of the target steering variable" The model formula for calculating the target steering angle θh*, which is the value of the target steering variable, is not limited to the above formula (c1). For example, a model in which the term "K·θh*" is deleted from the above formula (c1) may be used. Also, for example, a model in which the term "C·θh*'" is deleted from the above formula (c1) may be used.

[0082] The input to the target steering angle calculation process M50 may be the target reaction force Ts* instead of the turning torque command value Tt*. The process for calculating the value of the target steering variable is not limited to a process based on a model formula, but may be, for example, a map calculation.

[0083] "Operation status of the operating parts" The process for determining the operational state of the operating member is not limited to the operational state estimation process M60. For example, the operational state may be determined based only on the steering torque Th.

[0084] "About gradual change processing" It is not essential that the gradual-change processing variably sets the gradual-change speed in accordance with the vehicle speed V and the steering angular velocity ωh. For example, the gradual-change speed may be variably set in accordance with the vehicle speed V, but not in accordance with the steering angular velocity ωh. Alternatively, for example, the gradual-change speed may be variably set in accordance with the steering angular velocity ωh, but not in accordance with the vehicle speed V. Furthermore, the gradual-change processing does not have to be variably set in accordance with at least one of the vehicle speed V and the steering angular velocity ωh.

[0085] "About the switching process" When executing the switching process M62, it is not necessary to execute the gradual change process M64. "About control gain" When the process of varying the contribution rate R of the target reaction force Ts2* to the target reaction force Ts* is executed, the gains of various controls may be changed accordingly. That is, for example, the gain of the feedback amount calculation process M26 may be variably set. Also, for example, the gain of the steering angular velocity feedback process M48 may be variably set. Also, for example, the gain of the yaw rate feedback process M48a may be variably set. Also, for example, the gain of the steering angle feedback process M52 may be variably set.

[0086] The process of variably setting the gain is not limited to the case of executing the contribution rate variable process M70. For example, when the output value of the composite value calculation process M30, M30a is set to the target reaction force Ts*, the gain may be variably set according to the operation state by the driver. Here, the variable indicating the operation state that is input to the process of variably setting the gain is one that can identify whether the driver is operating the steering wheel 12 or not. This variable may take three or more values, such as the magnitude of the steering torque Th.

[0087] "About calculation processing for automatic control" 5, when the input of the damping process is the yaw rate yr, the damping process is combined with the yaw rate feedback process M48a, but this is not limiting. For example, the damping process M42a and the steering angular velocity feedback process M48 may be combined. Also, for example, the damping process M42 and the yaw rate feedback process M48a may be combined.

[0088] "About the use of calculation processing for automatic control" The use of the calculation process for automatic control is not limited to calculating the operation amount when the driver releases his / her hands from the steering wheel 12, which is an operating member. For example, the calculation process may be used to control the steering angle θh when the steering wheel 12 is shifted from a retracted state to a state that is easy for the driver to operate.

[0089] "Torque control processing" The control method for the reaction motor 20 is not limited to dq-axis current feedback processing. For example, if a DC motor is used as the reaction motor 20 and the drive circuit is an H-bridge circuit, it is sufficient to simply control the current flowing through the reaction motor 20.

[0090] "About the required torque variable" The required torque variable is not limited to the target reaction force Ts*. In other words, it is not limited to the target value of torque for the reaction motor 20. For example, if the reaction motor 20 is a surface permanent magnet synchronous motor, it may be a command value of the q-axis current. Also, if the reaction motor 20 is an interior permanent magnet synchronous motor, it may be a set of command values ​​of the d-axis current and the q-axis current.

[0091] The required torque variable is not limited to a variable indicating the reaction force applied to the steering wheel 12. For example, as described in the section "About the steering system" below, in the case of a device capable of transmitting power between the steering wheel 12 and the steered wheels 44, the required torque variable is a variable indicating a torque that assists the torque applied to the steering wheel 12 by the driver.

[0092] "Regarding steering angle control" Instead of the pinion angle feedback process M16, a process may be used in which a detected value of the movement amount of the steered shaft 40 is controlled to a target value by feedback control. In this case, in the above embodiment, the control amount and the like related to the pinion angle θp are replaced with the control amount and the like related to the movement amount of the steered shaft 40.

[0093] It is not essential that the control of the steering angle include a process of calculating a manipulated variable for controlling a control variable indicating the steering angle, such as pinion angle θp, by feedback control. For example, the control of the steering angle may include a process of calculating a manipulated variable for controlling a control variable indicating the steering angle to a target value by open-loop control. Also, for example, the control of the steering angle may include a process of calculating the sum of the manipulated variable for open-loop control and the manipulated variable for feedback control.

[0094] The control method for steering motor 60 is not limited to dq-axis current feedback processing. For example, if a DC motor is used as steering motor 60 and the drive circuit is an H-bridge circuit, it is sufficient to simply control the current flowing through steering motor 60.

[0095] "About the operating parts" The operating member operated by the driver to steer the vehicle is not limited to the steering wheel 12. For example, it may be a joystick.

[0096] "Motors mechanically connected to operating members" (a) Reaction Actuator Ar The reaction motor 20 mechanically connected to the steering wheel 12 is not limited to a three-phase brushless motor. For example, it may be a DC motor with brushes.

[0097] (b) Motor drive circuit The drive circuit for the motor mechanically connected to the operating member is not limited to the reaction force inverter 22. For example, it may be an H-bridge circuit.

[0098] (c) Other The provision of the reduction mechanism 16 is not essential. "About steering control devices" The steering control device is not limited to one that includes a PU 72 and a storage device 74 and executes software processing. For example, it may include a dedicated hardware circuit such as an ASIC that executes at least part of the processing executed in the above embodiment. That is, the control device may include a processing circuit having any of the following configurations (a) to (c): (a) A processing circuit that includes a processing device that executes all of the above processing in accordance with a program, and a program storage device such as a storage device that stores the program. (b) A processing circuit that includes a processing device and a program storage device that executes part of the above processing in accordance with a program, and a dedicated hardware circuit that executes the remaining processing. (c) A processing circuit that includes a dedicated hardware circuit that executes all of the above processing. Here, there may be multiple software execution devices that include a processing device and a program storage device. Also, there may be multiple dedicated hardware circuits.

[0099] "About steering actuators" The steering actuator At may be, for example, one in which steering motor 60 is arranged coaxially with steering shaft 40. Alternatively, for example, one in which steering motor 60 is connected to steering shaft 40 via a belt-type reducer using a ball screw mechanism may be used.

[0100] The steering actuator At is not limited to a configuration in which the right steered wheels 44 and the left steered wheels 44 are linked together. In other words, the steering actuator At may be one that can control the right steered wheels 44 and the left steered wheels 44 independently.

[0101] "About the steering device" The steering device capable of changing the relationship between the steering angle and the turning angle is not limited to a steering system in which the transmission of power between the steering wheel 12 and the steered wheels 44 is cut off. For example, a steering device capable of changing the relationship between the steering angle and the turning angle may be configured by using a variable gear as the gear that enables the transmission of power between the steering wheel 12 and the steered wheels 44. Furthermore, the steering device is not limited to a steering device in which the relationship between the steering angle and the turning angle is changeable. For example, a steering device in which the steering wheel 12 and the steered wheels 44 are mechanically connected may be used.

Claims

1. A steering control device configured to operate a motor mechanically coupled to an operating member operated by a driver to steer a vehicle, the steering control device is configured to execute a torque control process, a feedback amount calculation process, and an automatic control calculation process; the torque control process is a process of controlling the torque of the motor in accordance with a value of a required torque variable, the required torque variable is a variable indicating a target value of torque of the motor, the feedback amount calculation process is a process of calculating a value of the required torque variable so as to control the steering torque to a target steering torque by feedback control, the steering torque is a torque input to the operation member, A steering control device, wherein the automatic control calculation process is a process for calculating the value of the required torque variable for displacing the operating member separately from the operation of the operating member by the driver.

2. the automatic control calculation process includes a damping process of calculating a value of the required torque variable in accordance with a value of a turning speed variable, 2. The steering control device according to claim 1, wherein the turning speed variable is a variable indicating the rotation speed of the motor or the yaw rate of the vehicle.

3. 3. The steering control device according to claim 2, wherein the value of the required torque variable that is input to the torque control process is a combined value of the value of the required torque variable calculated by the feedback amount calculation process and the value of the required torque variable calculated by the automatic control calculation process.

4. configured to execute a target steering torque calculation process, the target steering torque calculation process is a process of calculating the target steering torque in accordance with a value of a vehicle speed variable, the vehicle speed variable is a variable indicating a traveling speed of the vehicle, 4. The steering control device according to claim 3, wherein the damping process is a process for calculating the value of the required torque variable in accordance with the value of the turning speed variable and the value of the vehicle speed variable.

5. the automatic control calculation process includes, in addition to the damping process, a turning speed feedback process of calculating the value of the required torque variable as an operation amount for controlling the value of the turning speed variable to the value of a target turning speed variable by feedback control, 5. The steering control device according to claim 2, wherein the turning speed variable is a variable indicating the rotation speed of the motor or the yaw rate of the vehicle.

6. the automatic control calculation process includes a turning speed feedback process that calculates the value of the required torque variable as an operation amount for controlling the value of the turning speed variable to the value of the target turning speed variable by feedback control, 2. The steering control device according to claim 1, wherein the turning speed variable is a variable indicating the rotation speed of the motor or the yaw rate of the vehicle.

7. configured to execute a target turning speed calculation process, the target turning speed calculation process is a process of calculating a value of the target turning speed variable in accordance with a value of a steering variable, 7. A steering control device according to claim 5, wherein the steering variable is a variable indicating a displacement amount of the operating member.

8. A steering control device according to any one of claims 5 to 7, wherein the value of the required torque variable that is input to the torque control processing is a combined value of the value of the required torque variable calculated by the feedback amount calculation processing and the value of the required torque variable calculated by the automatic control calculation processing.

9. configured to execute a target turning speed calculation process, the target turning speed calculation process is a process of calculating a value of the target turning speed variable in accordance with a value of a vehicle speed variable, 9. The steering control device according to claim 8, wherein the vehicle speed variable is a variable indicating a traveling speed of the vehicle.

10. the automatic control calculation process includes a steering feedback process for calculating the value of the required torque variable as an operation amount for controlling the value of the steering variable to the value of the target steering variable by feedback control, 2. The steering control device according to claim 1, wherein the steering variable is a variable indicating a displacement amount of the operating member.

11. configured to perform a switching process; 8. A steering control device according to any one of claims 1, 2, 4, 5 and 7, wherein the switching process switches the value of the required torque variable, which is input to the torque control process, to one of two values: the value of the required torque variable calculated by the feedback amount calculation process and the value of the required torque variable calculated by the automatic control calculation process, depending on the operation state of the operating member.

12. configured to perform a gradual change process; 12. A steering control device according to claim 11, wherein the gradual change processing is a processing for gradually transitioning the value of the required torque variable, which is an input to the torque control processing, from the first value to the second value when the switching processing switches from a first value of the required torque variable calculated by the feedback amount calculation processing and the required torque variable calculated by the automatic control calculation processing to a second value.

13. configured to perform a variable contribution rate process; the contribution rate varying process is a process in which, using a value of a steering torque variable as an input, the contribution rates of the value of the required torque variable calculated by the feedback amount calculation process and the value of the required torque variable calculated by the automatic control calculation process to the value of the required torque variable that is an input to the torque control process are changed, the steering torque variable is a variable indicating a steering torque, 8. A steering control device according to claim 1, wherein the steering torque is a torque applied to the operating member.

14. The steering control device according to any one of claims 1 to 13, wherein the torque control process is executed in a state where the operating member and the steered wheels of the vehicle are mechanically separated.

15. A steering control method for operating a motor mechanically connected to an operating member operated by a driver to steer a vehicle, comprising: the steering control method includes executing a torque control process, executing a feedback amount calculation process, and executing an automatic control calculation process; the torque control process is a process of controlling the torque of the motor in accordance with a value of a required torque variable, the required torque variable is a variable indicating a target value of torque of the motor, the feedback amount calculation process is a process of calculating a value of the required torque variable so as to control the steering torque to a target steering torque by feedback control, the steering torque is a torque input to the operation member, The steering control method, wherein the automatic control calculation process is a process of calculating a value of the required torque variable for displacing the operating member separately from the operation of the operating member by the driver.

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