Steering control device

Abstract

A steering control device configured to control a steering device (2) and including a control unit. The control unit is configured to calculate a torque command value as a target value of motor torque based on execution of angle control for adjusting a convertible angle convertible to a rotation angle of a motor to a target angle; calculate a motor control signal based on the torque command value; and change a control gain for the angle control based on a change in a factor affecting behavior of a vehicle in response to steering.

Description

Technical Field

[0001] The present invention relates to a steering control device. Background Art

[0002] In the prior art, an electric power steering system (EPS) that uses a motor to apply an assisting force to assist a driver's steering is known as a steering device for a vehicle. A steer-by-wire (SBW) steering device (in other words, a steer-by-wire steering system) is also known as a steering device for a vehicle. In the steer-by-wire steering device, the power transmission between a steering unit steered by a driver and a turning unit that turns turning wheels according to the driver's steering is cut off. A steering control device that controls such a steering device is controlled by performing angle feedback control for making the turning angle of the turning wheels coincide with a target turning angle, so that an improvement in steering feel or an improvement in turning characteristics of the turning wheels or the like is achieved.

[0003] Recently, a redundancy in a configuration for applying motor torque to a steering device has been developed. For example, Japanese Unexamined Patent Application Publication No. 2018-47875 (JP 2018-47875A) discloses the following configuration: In this configuration, a motor including two coil groups having different power supply paths is employed as a motor for applying motor torque to the steering device. In the steering control device disclosed in this publication, a group including a microcomputer and drive circuits corresponding to the two coil groups is included. The microcomputer controls the power supply to the two coil groups by controlling the corresponding drive circuits. That is, two control systems are constructed between the motor and the steering control device, and the two control systems respectively control the torques generated in the two coil groups. Therefore, for example, even when an abnormality occurs in one of the two control systems, the motor torque can be continuously applied from the motor to the steering device by supplying power to the corresponding coil group via the other control system. Summary of the Invention

[0004] In the configuration described in JP 2018-47875A, the drive mode of the motor changes, for example, when an abnormality occurs in one of the two control systems and when both control systems are normal. Therefore, even when the current command value for the motor is the same, the rotation angle of the motor is not the same. That is, the device characteristics (i.e., the transfer function) of a system having the current command value of the motor as an input and the rotation angle of the motor as an output change according to the drive mode of the motor. When the device characteristics change in this way, for example, the conformity between the steering angle and the target turning angle changes, and thus the behavior of the vehicle in response to steering may be affected.

[0005] Factors affecting the behavior of a vehicle in response to steering are not limited to the drive mode of the motor, but also include, for example, changes in the load state applied to the steering device, such as whether a braking operation is performed.

[0006] The present invention provides a steering control device that can optimize the behavior of a vehicle in response to steering.

[0007] One aspect of the present invention relates to a steering control device configured to control a steering device to which motor torque is applied from an actuator having a motor as a drive source. The steering control device includes: a control unit configured to output a motor control signal for controlling the operation of the motor; and a drive circuit configured to supply drive power to the motor based on the motor control signal. The control unit is configured to: calculate a torque command value, which is a target value of the motor torque, based on the execution of angle control for adjusting a convertible angle that can be converted into the rotation angle of the motor to a target angle; calculate the motor control signal based on the torque command value; and change a control gain for the angle control based on changes in factors affecting the behavior of the vehicle in response to steering.

[0008] With this configuration, since the control gain for the angle control is changed based on changes in factors affecting the behavior of the vehicle in response to steering, the angle control can be optimized according to the factors, and the optimization of the behavior of the vehicle in response to steering can be achieved.

[0009] In the steering control device, the motor may include a plurality of coil groups having different power supply paths; a plurality of groups each including a control unit and a drive circuit may be provided such that the groups respectively correspond to the coil groups, and the number of these groups is the same as the number of coil groups; a plurality of control systems may be provided between the motor and the steering control device, and the control systems are configured to individually control the torque generated by the coil groups; and the factors may include the drive mode of the motor.

[0010] With this configuration, since the control gain changes according to the drive mode, even when the degree of adjustment of the convertible angle relative to the target angle due to the execution of the angle control is changed by changing the drive mode, the angle control can be optimized and the optimization of the behavior of the vehicle in response to steering can be achieved.

[0011] In a steering control device, drive modes may include: a cooperative mode in which torque generated by a coil group of a control system is controlled based on a torque command value calculated by a control unit of one of the control systems in the control system; an independent mode in which torque generated by respective coil groups of the coil group of the control system is controlled based on a torque command value calculated by a control unit of the corresponding control system in the control system; and a residual mode in which, when one of the control systems in the control system is abnormal, torque generated by a coil group of the remaining control system in the control system is controlled based on a torque command value calculated by a control unit of the normal remaining control system in the control system; and a control gain may be changed such that the control gain increases in the order of the independent mode, the cooperative mode, and the residual mode.

[0012] With this configuration, in the order of the independent mode, the cooperative mode, and the residual mode, it is less likely to generate a large motor torque (i.e., the possibility of generating a large motor torque is reduced). Therefore, by increasing the control gain in this order, optimal angle control can be performed according to the drive mode of the motor.

[0013] In a steering control device, the factor may include vehicle speed, and the control gain may be changed such that the control gain increases as the vehicle speed increases. As the vehicle speed increases, the required torque for turning the turning wheels increases. Therefore, the degree of adjustment of the convertible angle relative to the target angle due to the execution of the angle control is changed by the change in vehicle speed, and the behavior of the vehicle in response to steering is affected. In this regard, with this configuration, since the control gain increases as the vehicle speed increases, optimal angle control can be performed according to the vehicle speed.

[0014] In a steering control device, the factor may include the acceleration - deceleration state of the vehicle, and the control gain can be changed to be smaller when the vehicle is in a decelerated state than when the vehicle is in a non - decelerated state.

[0015] When the vehicle is in a decelerated state, the center of gravity of the vehicle moves forward. Therefore, a stability factor, which is a value based on the difference between the load acting on the front wheels and the load acting on the rear wheels, may have a negative value, and the vehicle may oversteer. In this regard, with this configuration, since the control gain decreases when the vehicle is in a decelerated state, oversteering can be suppressed and an improvement in steering feel can be achieved.

[0016] In a steering control device, the factor may include lateral acceleration, and the control gain may be changed such that the control gain increases as the absolute value of the lateral acceleration increases. As the lateral acceleration increases, the torque required to turn the turning wheels increases. Accordingly, the degree of adjustment of the convertible angle with respect to the target angle due to the execution of angle control is changed by the change in the lateral acceleration, and the behavior of the vehicle in response to steering is affected. In this regard, with this configuration, since the control gain increases as the absolute value of the lateral acceleration increases, optimal angle control can be performed according to the lateral acceleration.

[0017] In a steering control device, the factor may include at least one object temperature among the temperature of a motor, the temperature of a control unit, the temperature of a drive circuit, the temperature of a steering device, and the ambient temperature around the steering device, and the control gain may be changed such that the control gain increases as the object temperature decreases.

[0018] As the temperature of the motor decreases, for example, the viscosity of the grease in the motor increases, and thus a greater torque is required to rotate the motor. This is not limited to the temperature of the motor, and this can be applied to other temperatures. Accordingly, the degree of adjustment of the convertible angle with respect to the target angle due to the execution of angle control is changed by the change in the object temperature, and the behavior of the vehicle in response to steering is affected. In this regard, with this configuration, since the control gain increases as the object temperature decreases, optimal angle control can be performed according to the object temperature.

[0019] In a steering control device, the angle control may include feedback control for making the convertible angle conform to the target angle, and the control gain may include a feedback gain for the feedback control.

[0020] In a steering control device, the angle control may include feedforward control based on the target angle, and the control gain may include a feedforward gain for the feedforward control.

[0021] In a steering control device, the angle control may include damping control based on a target angular velocity that is a rate of change of the target angle, and the control gain may include a damping gain for the damping control.

[0022] With these configurations, the convertible angle can be appropriately adjusted to the target angle.

[0023] According to an aspect of the present invention, optimization of the behavior of the vehicle in response to steering can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in the drawings:

[0025] Figure 1 is a diagram schematically showing the configuration of a steering device;

[0026] Figure 2 is a block diagram showing a steering control device, a steering-side motor, and a turning-side motor;

[0027] Figure 3 is a block diagram showing a steering-side microcomputer;

[0028] Figure 4 is a block diagram showing a target reaction torque calculation unit;

[0029] Figure 5 is a block diagram showing a first turning-side microcomputer and a second turning-side microcomputer;

[0030] Figure 6 is a block diagram showing an existing target turning torque calculation unit;

[0031] Figure 7 is a block diagram showing an angle feedback torque calculation unit;

[0032] Figure 8 is a block diagram showing a proportional gain calculation unit;

[0033] Figure 9 is a block diagram showing an angle feedforward torque calculation unit; and

[0034] Figure 10 is a block diagram showing a damping torque calculation unit. DETAILED DESCRIPTION

[0035] Hereinafter, a steering control device according to an embodiment will be described with reference to the drawings. As Figure 1 shown, a steering device 2 controlled by a steering control device 1 according to the present embodiment is configured as a steer-by-wire type steering device (in other words, a steer-by-wire system). The steering device 2 includes: a steering unit 4 that is steered by a driver using a steering wheel 3; and a turning unit 6 that turns turning wheels 5 according to the steering of the steering unit 4 by the driver.

[0036] The steering unit 4 includes: a steering shaft 11 fixed to the steering wheel 3; and a steering-side actuator 12 that applies a steering reaction force to the steering wheel 3 via the steering shaft 11. The steering reaction force is a force that resists the driver's steering. The steering-side actuator 12 includes: a steering-side motor 13 serving as a drive source, and a steering-side reduction gear 14 that decelerates the rotation of the steering-side motor 13 (i.e., reduces the rotational speed) and transmits the decelerated rotation to the steering shaft 11. That is, the steering-side motor 13 applies its motor torque as the steering reaction force. For example, in the present embodiment, a three-phase surface permanent magnet synchronous motor (SPMSM) is used as the steering-side motor 13.

[0037] The turning unit 6 includes: a pinion shaft 21; a rack shaft 22 serving as a turning shaft connected to the pinion shaft 21; a rack housing 23 that houses the rack shaft 22 such that the rack shaft 22 can reciprocate; and a rack and pinion mechanism 24 including the pinion shaft 21 and the rack shaft 22. The pinion shaft 21 and the rack shaft 22 are arranged to have a predetermined crossing angle. The pinion teeth 21a formed in the pinion shaft 21 and the rack teeth 22a formed in the rack shaft 22 mesh with each other to constitute the rack and pinion mechanism 24. That is, the pinion shaft 21 corresponds to a rotating shaft whose rotation angle can be converted into the turning angle of the turning wheels 5. Tie rods 26 are respectively connected to both ends of the rack shaft 22 via rack ends 25, and each of the rack ends 25 in the rack ends is formed by a spherical joint. The ends of the tie rods 26 are connected to steering knuckles (not shown) to which the right turning wheels 5 and the left turning wheels 5 are assembled.

[0038] The turning unit 6 includes a turning-side actuator 31 that applies a turning force for turning the turning wheels 5 to the rack shaft 22. The turning-side actuator 31 includes a turning-side motor 32 serving as a drive source, a transmission mechanism 33, and a conversion mechanism 34. The turning-side actuator 31 applies a turning force to the turning unit 6 by transmitting the rotation of the turning-side motor 32 to the conversion mechanism 34 via the transmission mechanism 33 and causing the conversion mechanism 34 to convert the rotation into the reciprocating motion of the rack shaft 22. That is, the turning-side motor 32 applies its motor torque as the turning force. In the present embodiment, for example, a surface permanent magnet synchronous motor is used as the turning-side motor 32, for example, a belt mechanism is used as the transmission mechanism 33, and for example, a ball screw mechanism is used as the conversion mechanism 34.

[0039] In the steering device 2 having the foregoing configuration, the turning angle of the turning wheels 5 is changed by applying a turning force from the turning-side actuator 31 to the rack shaft 22 according to the driver's steering operation. At this time, a steering reaction force is applied from the steering-side actuator 12 to the steering wheel 3.

[0040] The electrical configuration according to this embodiment will be described below. The steering control device 1 is connected to the steering-side motor 13 and the turning-side motor 32, and controls the operations of the steering-side motor 13 and the turning-side motor 32. The steering control device 1 includes a central processing unit (CPU) and a memory (not shown). Various types of control are executed by causing the CPU to execute a program stored in the memory in each predetermined operation cycle of a predetermined operation cycle.

[0041] The steering control device 1 controls the steering-side motor 13 and the turning-side motor 32 with reference to the state quantities detected by various sensors. The state quantities include: the steering torque Th detected by the torque sensor 41 and the vehicle speed Vb detected by the vehicle speed sensor 42. The torque sensor 41 is provided on the steering wheel 3 side of the portion of the steering shaft 11 connected to the steering-side reduction gear 14. The steering torque Th is the torque input by the driver using the steering wheel 3.

[0042] The state quantities include: the rotation angle θs of the output shaft 13a of the steering-side motor 13 detected by the steering-side rotation angle sensor 43, the rotation angle θt1 of the output shaft 32a of the turning-side motor 32 detected by the turning-side rotation angle sensor 44, and the rotation angle θt2 of the output shaft 32a of the turning-side motor 32 detected by the turning-side rotation angle sensor 45. The rotation angles θs, θt1, and θt2 are detected as relative angles within a range of 360°. The steering torque Th and the rotation angles θs, θt1, and θt2 are detected as positive values, for example, when executing a right turn and are detected as negative values when executing a left turn. When the turning-side rotation angle sensors 44 and 45 are normal, the rotation angles θt1 and θt2 substantially have the same value.

[0043] The state quantities include: the object temperature Temp detected by the temperature sensor 46, the lateral acceleration γ detected by the lateral acceleration sensor 47, and the brake operation flag Fbr indicating whether a brake (not shown) is operated. The object temperature Temp is the temperature of the turning-side motor 32. The brake operation flag Fbr is input from a brake control device 48 that controls the operation of the brake.

[0044] The configurations of the steering-side motor 13 and the turning-side motor 32 will be described below. As Figure 2 shown, the steering-side motor 13 includes a rotor 51 and a coil group 52 wound around a stator (not shown). The coil group 52 includes three-phase coils of U, V, and W. Each phase coil of the coil group 52 is connected to form a single power supply path and is connected to the steering control device 1 via a connection line 53.

[0045] The turning-side motor 32 includes a rotor 54, a first coil group 55, and a second coil group 56. Each of the first coil group 55 and the second coil group 56 includes three-phase coils of U, V, and W. Each phase coil of the first coil group 55 and each phase coil of the second coil group 56 are connected to form independent power supply paths. Each phase coil of the first coil group 55 is connected to the steering control device 1 via a first connection line 57. Each phase coil of the second coil group 56 is connected to the steering control device 1 via a second connection line 58.

[0046] The configuration of the steering control device 1 will be described in detail below. The steering control device 1 includes: a steering-side microcomputer 61 that outputs a steering-side motor control signal Ms, and a steering-side drive circuit 62 that supplies drive power to the coil group 52 based on the steering-side motor control signal Ms. The rotation angle θs, the steering torque Th, and the vehicle speed Vb are input to the steering-side microcomputer 61. The steering-side microcomputer 61 is connected to a current sensor 63 that detects the phase current values Ius, Ivs, and Iws flowing in the connection line 53 of the steering-side motor 13. In Figure 2 For ease of description, the connection lines 53 of each phase and the current sensors 63 of each phase are collectively shown as a single one.

[0047] The steering control device 1 includes: a first turning-side microcomputer 64 as a control unit that outputs a first turning-side motor control signal Mt1, and a first turning-side drive circuit 65 that supplies drive power to the first coil group 55 based on the first turning-side motor control signal Mt1. The rotation angle θt1, the brake operation flag Fbr, the vehicle speed Vb, the lateral acceleration γ, and the object temperature Temp are input to the first turning-side microcomputer 64. The first turning-side microcomputer 64 is connected to a first current sensor 66 that detects the phase current values Iut1, Ivt1, and Iwt1 flowing in the first connection line 57 of the turning-side motor 32. In Figure 2 For ease of description, the first connection lines 57 of each phase and the first current sensors 66 of each phase are collectively shown as a single one.

[0048] The steering control device 1 includes: a second turning-side microcomputer 67 as a control unit that outputs a second turning-side motor control signal Mt2, and a second turning-side drive circuit 68 that supplies drive power to the second coil group 56 based on the second turning-side motor control signal Mt2. The rotation angle θt2, the brake operation flag Fbr, the vehicle speed Vb, the lateral acceleration γ, and the object temperature Temp are input to the second turning-side microcomputer 67. The second turning-side microcomputer 67 is connected to a second current sensor 69 that detects the phase current values Iut2, Ivt2, and Iwt2 flowing in the second connection line 58 of the turning-side motor 32. In Figure 2In order to facilitate description, the second connection lines 58 of each phase and the second current sensors 69 of each phase are collectively shown as a single unit.

[0049] That is to say, the steering control device 1 includes a set of a first turning-side microcomputer 64 and a first turning-side drive circuit 65 corresponding to the first coil group 55, and a set of a second turning-side microcomputer 67 and a second turning-side drive circuit 68 corresponding to the second coil group 56. The set of the first turning-side microcomputer 64 and the first turning-side drive circuit 65 controls the power supply to the first coil group 55. The second turning-side microcomputer 67 and the second turning-side drive circuit 68 control the power supply to the second coil group 56.

[0050] The steering-side microcomputer 61, the first turning-side microcomputer 64, and the second turning-side microcomputer 67 are connected to each other. Therefore, the steering-side microcomputer 61, the first turning-side microcomputer 64, and the second turning-side microcomputer 67 transmit various signals to and receive various signals from each other.

[0051] The steering-side drive circuit 62, the first turning-side drive circuit 65, and the second turning-side drive circuit 68 employ, for example, a PWM inverter including a plurality of switching elements such as FETs. The steering-side motor control signal Ms, the first turning-side motor control signal Mt1, and the second turning-side motor control signal Mt2 are gate on / off signals for specifying the on / off states of the switching elements.

[0052] When the steering-side motor control signal Ms is output to the steering-side drive circuit 62, drive power is supplied from the vehicle-mounted power source B to the steering-side motor 13. Therefore, the steering control device 1 controls the torque generated in the coil group 52, that is, the torque generated in the steering-side motor 13, by supplying drive power to the coil group 52.

[0053] When the first turning side motor control signal Mt1 is output to the first turning side drive circuit 65, drive power is supplied from the vehicle-mounted power source B to the first coil group 55. When the second turning side motor control signal Mt2 is output to the second turning side drive circuit 68, drive power is supplied from the vehicle-mounted power source B to the second coil group 56. Therefore, the steering control device 1 controls the torque generated in the first coil group 55 by supplying drive power to the first coil group 55, and controls the torque generated in the second coil group 56 by supplying drive power to the second coil group 56. That is, a first control system and a second control system for separately controlling the torques generated in the first coil group 55 and the second coil group 56 are provided between the steering control device 1 and the turning side motor 32. The torque generated in the turning side motor 32 is the sum of the torque generated in the first coil group 55 and the torque generated in the second coil group 56. That is, the steering control device 1 controls the torque generated in the turning side motor 32 by supplying drive power to the first coil group 55 and supplying drive power to the second coil group 56.

[0054] The configuration of the steering side microcomputer 61 will be described below. As Figure 3 shown, the steering side microcomputer 61 calculates the steering side motor control signal Ms by executing the operation processing represented by the following control blocks in each predetermined operation cycle in a predetermined operation cycle. The steering torque Th, the vehicle speed Vb, the rotation angle θs, the phase current values Ius, Ivs, and Iws, the q-axis current values Iqt1 and Iqt2 as the drive currents of the turning side motor 32, and the first turning corresponding angle θp1 are input to the steering side microcomputer 61. Then, the steering side microcomputer 61 calculates the steering side motor control signal Ms based on the state quantities.

[0055] Specifically, the steering side microcomputer 61 includes: a steering angle calculation unit 71 that calculates the steering angle θh of the steering wheel 3 based on the rotation angle θs; a target reaction torque calculation unit 72 that calculates the target reaction torque Ts*; and a steering side motor control signal calculation unit 73 that calculates the steering side motor control signal Ms. The target reaction torque Ts* is the target value of the motor torque output from the steering side motor 13.

[0056] The rotation angle θs of the steering-side motor 13 is input to the steering angle calculation unit 71. The steering angle calculation unit 71 converts the rotation angle θs into an absolute angle within a range including more than 360° by, for example, counting the number of revolutions of the steering-side motor 13 from the steering neutral position, and obtains the absolute angle. The steering angle calculation unit 71 calculates the steering angle θh by multiplying the rotation angle converted into the absolute angle by a first conversion factor. The first conversion factor is preset based on the rotation speed ratio of the steering-side reduction gear 14. The calculated steering angle θh is output to the first turning-side microcomputer 64 and the second turning-side microcomputer 67.

[0057] The steering torque Th, the vehicle speed Vb, the q-axis current values Iqt1 and Iqt2, and the first turning corresponding angle θp1 are input to the target reaction torque calculation unit 72. As will be described later, the target reaction torque calculation unit 72 calculates the target reaction torque Ts* based on the state quantity, and outputs the calculated target reaction torque Ts* to the steering-side motor control signal calculation unit 73.

[0058] In addition to the target reaction torque Ts*, the rotation angle θs and the phase current values Ius, Ivs, and Iws are input to the steering-side motor control signal calculation unit 73. The steering-side motor control signal calculation unit 73 calculates a d-axis current command value Ids* on the d-axis and a q-axis current command value Iqs* on the q-axis in the dq coordinate system based on the target reaction torque Ts*. The current command values Ids* and Iqs* represent the current command value on the d-axis and the current command value on the q-axis in the dq coordinate system.

[0059] Specifically, the steering-side motor control signal calculation unit 73 calculates the q-axis current command value Iqs* whose absolute value increases as the absolute value of the target reaction torque Ts* increases. In the present embodiment, the d-axis current command value Ids* on the d-axis is basically set to zero. The steering-side motor control signal calculation unit 73 calculates the steering-side motor control signal Ms by performing current feedback control in the dq coordinate system. In the following description, the word "feedback" may be referred to as "F / B".

[0060] More specifically, the steering-side motor control signal calculation unit 73 calculates the d-axis current value Ids and the q-axis current value Iqs by mapping the phase current values Ius, Ivs, and Iws to the dq coordinate system based on the rotation angle θs. The d-axis current value Ids and the q-axis current value Iqs are the actual current values of the steering-side motor 13 in the dq coordinate system. Then, the steering-side motor control signal calculation unit 73 calculates the target voltage value based on the current difference on the d-axis and the current difference on the q-axis, such that the d-axis current value Ids conforms to the d-axis current command value Ids* and the q-axis current value Iqs conforms to the q-axis current command value Iqs*. The steering-side motor control signal calculation unit 73 calculates the steering-side motor control signal Ms with a duty ratio (i.e., duty factor) based on the target voltage value.

[0061] The calculated steering-side motor control signal Ms is output to the steering-side drive circuit 62. Therefore, the drive power corresponding to the steering-side motor control signal Ms is supplied from the steering-side drive circuit 62 to the steering-side motor 13. The motor torque indicated by the target reaction torque Ts* is generated from the first coil group 52 and the steering reaction force is applied to the steering wheel 3.

[0062] The target reaction torque calculation unit 72 will be described below. As Figure 4 shown, the target reaction torque calculation unit 72 includes an input torque base component calculation unit 81 that calculates the input torque base component Tb and a reaction component calculation unit 82 that calculates the reaction component Fir. The input torque base component Tb is the force for rotating the steering wheel 3 in the driver's steering direction. The reaction component Fir is the force that resists the rotation of the steering wheel 3 caused by the driver's steering.

[0063] Specifically, the steering torque Th is input to the input torque base component calculation unit 81. The input torque base component calculation unit 81 calculates the input torque base component Tb whose absolute value increases as the absolute value of the steering torque Th increases. The calculated input torque base component Tb is output to the subtractor 83.

[0064] The vehicle speed Vb, the q-axis current values Iqt1 and Iqt2 of the turning-side motor 32, and the first turning corresponding angle θp1 are input to the reaction component calculation unit 82. The reaction component calculation unit 82 calculates the reaction component Fir corresponding to the axial force applied to the rack shaft 22 based on the state quantity. The reaction component Fir corresponds to the calculated axial force obtained by estimating the axial force applied to the rack shaft 22.

[0065] Specifically, the reaction force component calculation unit 82 includes: an angular axial force calculation unit 85 that calculates the angular axial force Fib; and a current axial force calculation unit 86 that calculates the current axial force Fer. The angular axial force Fib and the current axial force Fer are calculated in the dimension of torque (N·m). The reaction force component calculation unit 82 includes a distributed axial force calculation unit 87 that calculates the reaction force component Fir by adding the angular axial force Fib and the current axial force Fer at a preset distribution ratio set separately. The preset distribution ratio is set such that the axial force applied from the road surface to the turning wheel 5, that is, the road surface information transmitted from the road surface, is reflected in the reaction force component Fir.

[0066] The first turning corresponding angle θp1 and the vehicle speed Vb are input to the angular axial force calculation unit 85. The angular axial force calculation unit 85 calculates the angular axial force Fib based on the first turning corresponding angle θp1 and the vehicle speed Vb. The angular axial force Fib is the ideal value of the axial force in an arbitrarily set model and is the axial force that does not include road surface information, such as minute unevenness that does not affect the lateral behavior of the vehicle or a step portion that affects the lateral behavior of the vehicle.

[0067] Specifically, the angular axial force calculation unit 85 calculates the angular axial force Fib whose absolute value increases as the absolute value of the first turning corresponding angle θp1 increases. The angular axial force calculation unit 85 calculates the angular axial force Fib whose absolute value increases as the vehicle speed Vb increases. The calculated angular axial force Fib is output to the distributed axial force calculation unit 87.

[0068] The q-axis current values Iqt1 and Iqt2 of the turning side motor 32 are input to the current axial force calculation unit 86. The current axial force calculation unit 86 calculates the sum of the q-axis current value Iqt1 and the q-axis current value Iqt2 as the q-axis current value Iqt. The current axial force calculation unit 86 calculates the axial force applied to the turning wheel 5 based on the q-axis current value Iqt. The current axial force Fer is an estimated value of the axial force applied to the turning wheel 5 and is the axial force that includes road surface information.

[0069] Specifically, the current axial force calculation unit 86 calculates the absolute value of the current axial force Fer whose absolute value increases as the absolute value of the q-axis current value Iqt increases. This is based on the assumption that the torque applied from the turning side motor 32 to the rack shaft 22 is balanced with the torque based on the force applied from the road surface to the turning wheel 5. The calculated current axial force Fer is output to the distributed axial force calculation unit 87.

[0070] The angular axial force Fib and the current axial force Fer are input to the distributed axial force calculation unit 87. In the distributed axial force calculation unit 87, a current distribution gain indicating the distribution ratio of the current axial force Fer and an angular distribution gain indicating the distribution ratio of the angular axial force Fib are preset in advance through experiments or the like. The distributed axial force calculation unit 87 calculates the reaction component Fir by adding the value obtained by multiplying the angular axial force Fib by the angular distribution gain and the value obtained by multiplying the current axial force Fer by the current distribution gain. The calculated reaction component Fir is output to the subtracter 83.

[0071] The target reaction torque calculation unit 72 calculates the target reaction torque Ts* by causing the subtracter 83 to subtract the reaction component Fir from the input torque base component Tb. The calculated target reaction torque Ts* is output to the steering side motor control signal calculation unit 73. That is, the target reaction torque calculation unit 72 calculates the target reaction torque Ts* based on the reaction component Fir as the calculated axial force. Therefore, the steering reaction force applied by the steering side motor 13 is basically a force that resists the driver's steering, and can be a force for assisting the driver's steering based on the difference between the calculated axial force and the actual axial force applied to the rack shaft 22.

[0072] The following will refer to Figure 5 to describe the first turning side microcomputer 64 and the second turning side microcomputer 67. The first turning side microcomputer 64 and the second turning side microcomputer 67 change the processing for calculating the first turning side motor control signal Mt1 and the second turning side motor control signal Mt2 according to the drive mode of the turning side motor 32.

[0073] In this embodiment, the drive mode of the turning side motor 32 includes three modes, in other words, the cooperation mode, the independent mode, and the remaining mode. The cooperation mode is the following drive mode: in this drive mode, the torque generated from the first coil group 55 and the second coil group 56 is controlled based on the previous target turning torque Tty* calculated by the first turning side microcomputer 64. The cooperation mode is executed when both the first control system for controlling the torque generated from the first coil group 55 and the second control system for controlling the torque generated from the second coil group 56 are normal and the inter-microcomputer communication between the first turning side microcomputer 64 and the second turning side microcomputer 67 is normal. The previous target turning torque Tty* will be described later.

[0074] The independent mode is the following drive mode: In this drive mode, the torque generated from the first coil group 55 is controlled based on the previous target turning torque Tty* calculated by the first turning side microcomputer 64, and the torque generated from the second coil group 56 is controlled based on the redundant target turning torque Ttj* calculated by the second turning side microcomputer 67. When both the first control system and the second control system are normal but the communication between the microcomputers is abnormal, the independent mode is executed. The redundant target turning torque Ttj* will be described later.

[0075] When one of the first control system and the second control system is abnormal, the remaining mode is executed. The remaining mode is the following drive mode: In this drive mode, when the first control system is normal, the torque generated from the first coil group 55 is controlled based on the previous target turning torque Tty*, and when the second control system is normal, the torque generated from the second coil group 56 is controlled based on the redundant target turning torque Ttj*.

[0076] The configuration of the first turning side microcomputer 64 will be described below. The first turning side microcomputer 64 calculates the first turning side motor control signal Mt1 by executing the operation process represented by the following control block in each predetermined operation cycle of the predetermined operation cycle. The rotation angle θt1, the steering angle θh, the steering torque Th, the phase current values Iut1, Ivt1, and Iwt1, the brake operation flag Fbr, the vehicle speed Vb, the lateral acceleration γ, and the object temperature Temp are input to the first turning side microcomputer 64. Then, the first turning side microcomputer 64 calculates the first turning side motor control signal Mt1 based on the state quantity and outputs the calculated first turning side motor control signal Mt1.

[0077] Specifically, the first turning side microcomputer 64 includes: a first turning corresponding angle calculation unit 91 that calculates a first turning corresponding angle θp1 based on the rotation angle θt1; a first target turning corresponding angle calculation unit 92 that calculates a first target turning corresponding angle θp1* based on the steering angle θh and the steering torque Th; and a first state management unit 93 that manages the drive mode of the first control system. The first target turning corresponding angle θp1* is the target value of the first turning corresponding angle θp1, which is the rotation angle of the rotation axis, i.e., the pinion shaft 21, and can be converted into the turning angle of the turning wheel 5. The first turning side microcomputer 64 includes: a previous target turning torque calculation unit 94 that calculates the previous target turning torque Tty*; a first target turning torque calculation unit 95 that calculates the first target turning torque Tt1*; and a first turning side motor control signal calculation unit 96 that calculates the first turning side motor control signal Mt1. The previous target turning torque Tty* is the target value of the motor torque output from the turning side motor 32 and corresponding to the torque command value. Therefore, the previous target turning torque calculation unit 94 corresponds to the torque command value calculation unit.

[0078] The rotation angle θt1 is input to the first turning corresponding angle calculation unit 91. The first turning corresponding angle calculation unit 91 converts the input rotation angle θt1 into an absolute angle, for example, by counting the number of revolutions of the turning side motor 32 from the neutral position where the vehicle travels straight, and obtains the absolute angle. The first turning corresponding angle calculation unit 91 calculates the first turning corresponding angle θp1 by multiplying the rotation angle that has been converted into an absolute angle by a second conversion factor. The second conversion coefficient is preset based on the reduction ratio of the transmission mechanism 33, the lead of the conversion mechanism 34, and the rotation speed ratio of the rack and pinion mechanism 24. That is, the first turning corresponding angle θp1 corresponds to the convertible angle that can be converted into the rotation angle θt1 of the turning side motor 32. When it is assumed that the pinion shaft 21 is connected to the steering shaft 11, the first turning corresponding angle θp1 substantially matches the steering angle θh of the steering wheel 3. The calculated first turning corresponding angle θp1 is output to the previous target turning torque calculation unit 94 and the target reaction torque calculation unit 72.

[0079] The steering angle θh and the steering torque Th are input to the first target turning corresponding angle calculation unit 92. The first target turning corresponding angle calculation unit 92 calculates the first target turning corresponding angle θp1* based on the state quantity. The first target turning corresponding angle calculation unit 92 calculates the first target turning corresponding angle θp1* such that the steering angle ratio, which is the ratio of the steering angle θh to the first turning corresponding angle θp1, is substantially 1:1.

[0080] Specifically, the first target turning corresponding angle calculation unit 92 calculates, as the first target turning corresponding angle θp1*, the value obtained by adding the compensation angle based on the steering torque Th to the steering angle θh. The compensation angle is the angle representing the torsion of the steering shaft 11 caused by the input steering torque Th, and is obtained by multiplying the steering torque Th by a preset compensation coefficient. The calculated first target turning corresponding angle θp1* is output to the previous target turning torque calculation unit 94.

[0081] Various state quantities including the rotation angles θt1 and θt2 and the phase current values Iut1, Ivt1, Iwt1, Iut2, Ivt2, and Iwt2 are input to the first state management unit 93. For ease of description, the state quantities input to the first state management unit 93 are not shown. The first state management unit 93 determines whether the first control system is normal based on the state quantity. For example, when the rotation angle θt1 has an impossible value or when the change amount compared with the previous value is greater than a preset threshold, the first state management unit 93 determines that an abnormality has occurred in the first control system.

[0082] The first state management unit 93 is connected to the second state management unit 103 of the second turning side microcomputer 67, which will be described later. The first state management unit 93 determines whether the inter-microcomputer communication between the first turning side microcomputer 64 and the second turning side microcomputer 67 is normal based on the signals sent to and received from the second state management unit 103. For example, when no signal is received from the second state management unit 103 or when a signal indicating that an abnormality has occurred in the second turning side microcomputer 67 is input, the first state management unit 93 determines that the inter-microcomputer communication is abnormal.

[0083] Based on the result of the abnormality determination, the first state management unit 93 outputs a first state signal S1 indicating the drive mode of the turning side motor 32 to the previous target turning torque calculation unit 94. Specifically, when the first control system and the second control system are normal and the inter-microcomputer communication is normal, the first state management unit 93 outputs the first state signal S1 indicating that the turning side motor 32 will operate in the cooperative mode. For example, when the first control system and the second control system are normal and the inter-microcomputer communication is abnormal, the first state management unit 93 outputs the first state signal S1 indicating that the turning side motor 32 will operate in the independent mode. When the second control system is abnormal, the first state management unit 93 outputs the first state signal S1 indicating that the turning side motor 32 will operate in the remaining mode.

[0084] The first target turning corresponding angle θp1*, the first turning corresponding angle θp1, the brake operation flag Fbr, the vehicle speed Vb, the lateral acceleration γ, the object temperature Temp, and the first state signal S1 are input to the previous target turning torque calculation unit 94. The previous target turning torque calculation unit 94 calculates the previous target turning torque Tty* based on the state quantities, as will be described later, and outputs the calculated previous target turning torque Tty* to the first target turning torque calculation unit 95 and the second turning side microcomputer 67.

[0085] The previous target turning torque Tty* is input to the first target turning torque calculation unit 95. The first target turning torque calculation unit 95 calculates the first target turning torque Tt1* based on the previous target turning torque Tty*. The first target turning torque Tt1* is the torque generated from the first coil group 55 when the turning side motor 32 generates the previous target turning torque Tty*. According to the present embodiment, the first target turning torque calculation unit 95 calculates half (50%) of the previous target turning torque Tty* as the first target turning torque Tt1*.

[0086] In addition to the first target turning torque Tt1*, the rotation angle θt1 and the phase current values Iut1, Ivt1, and Iwt1 are input to the first turning-side motor control signal calculation unit 96. The first turning-side motor control signal calculation unit 96 calculates a d-axis current command value Idt1* on the d-axis and a q-axis current command value Iqt1* on the q-axis in the dq coordinate system based on the first target turning torque Tt1*.

[0087] Specifically, the first turning-side motor control signal calculation unit 96 calculates the q-axis current command value Iqt1*, and the absolute value of the q-axis current command value Iqt1* increases as the absolute value of the first target turning torque Tt1* increases. In the present embodiment, the d-axis current command value Idt1* on the d-axis is basically set to zero. Similar to the steering-side motor control signal calculation unit 73, the first turning-side motor control signal calculation unit 96 calculates the first turning-side motor control signal Mt1 by performing current F / B control in the dq coordinate system (i.e., based on the execution of current F / B control in the dq coordinate system). The q-axis current value Iqt1 calculated during the calculation of the first turning-side motor control signal Mt1 is output to the target reaction torque calculation unit 72.

[0088] The calculated first turning-side motor control signal Mt1 is output to the first turning-side drive circuit 65. Accordingly, drive power corresponding to the first turning-side motor control signal Mt1 is supplied from the first turning-side drive circuit 65 to the turning-side motor 32. The motor torque represented by the first target turning torque Tt1* is generated from the first coil group 55, and a turning force is applied from the turning-side motor 32 to the turning wheel 5.

[0089] The configuration of the second turning-side microcomputer 67 will be described below. The second turning-side microcomputer 67 calculates the second turning-side motor control signal Mt2 by performing operation processing indicated by control blocks described below in each predetermined operation cycle during a predetermined operation cycle. The rotation angle θt2, the steering angle θh, the steering torque Th, the phase current values Iut2, Ivt2, and Iwt2, the brake operation flag Fbr, the vehicle speed Vb, the lateral acceleration γ, and the object temperature Temp are input to the second turning-side microcomputer 67. Then, the second turning-side microcomputer 67 calculates the second turning-side motor control signal Mt2 based on the state quantity and outputs the calculated second turning-side motor control signal Mt2.

[0090] Specifically, the second turning side microcomputer 67 is configured substantially similarly to the first turning side microcomputer 64. That is, the second turning side microcomputer 67 includes a second turning corresponding angle calculation unit 101 that calculates a second turning corresponding angle θp2, a second target turning corresponding angle calculation unit 102 that calculates a second target turning corresponding angle θp2*, and a second state management unit 103 that manages the drive mode of the second control system. The second turning corresponding angle θp2 corresponds to a convertible angle that can be converted into the rotation angle θt2 of the turning side motor 32. The second target turning corresponding angle θp2* is a target value of the second turning corresponding angle θp2, and the second turning corresponding angle θp2 is the rotation angle of the rotation shaft, i.e., the pinion shaft 21, which can be converted into the turning angle of the turning wheel 5. The second turning side microcomputer 67 includes a redundant target turning torque calculation unit 104 that calculates a redundant target turning torque Ttj*, a second target turning torque calculation unit 105 that calculates a second target turning torque Tt2*, and a second turning side motor control signal calculation unit 106 that calculates a second turning side motor control signal Mt2. The redundant target turning torque Ttj* is a target value of the motor torque output from the turning side motor 32 and corresponds to the torque command value. Therefore, the redundant target turning torque calculation unit 104 corresponds to the torque command value calculation unit.

[0091] Similar to the first turning corresponding angle calculation unit 91, the second turning corresponding angle calculation unit 101 calculates the second turning corresponding angle θp2 based on the rotation angle θt2. Similar to the first target turning corresponding angle calculation unit 92, the second target turning corresponding angle calculation unit 102 calculates the second target turning corresponding angle θp2* based on the steering angle θh and the steering torque Th.

[0092] Various state quantities including the rotation angles θt1 and θt2 and the phase current values Iut1, Ivt1, Iwt1, Iut2, Ivt2, and Iwt2 are input to the second state management unit 103. For the purpose of easy description, the state quantities input to the second state management unit 103 are not described. Similar to the first state management unit 93, the second state management unit 103 calculates a second state signal S2 and outputs the calculated second state signal S2 to the redundant target turning torque calculation unit 104 and the second target turning torque calculation unit 105.

[0093] The second turning corresponding angle θp2, the second target turning corresponding angle θp2*, the brake operation flag Fbr, the vehicle speed Vb, the lateral acceleration γ, the object temperature Temp, and the second state signal S2 are input to the redundant target turning torque calculation unit 104. Similar to the previous target turning torque calculation unit 94, which will be described later, the redundant target turning torque calculation unit 104 calculates the redundant target turning torque Ttj*.

[0094] In addition to the second state signal S2 and the redundant target turning torque Ttj*, when the inter-microcomputer communication is normal, the previous target turning torque Tty* is input to the second target turning torque calculation unit 105. When the second state signal S2 indicating that the drive mode of the turning side motor 32 is the cooperative mode is input, the second target turning torque calculation unit 105 calculates the second target turning torque Tt2* based on the previous target turning torque Tty*. On the other hand, when the second state signal S2 indicating that the drive mode of the turning side motor 32 is the independent mode or the remaining mode is input, the second target turning torque calculation unit 105 calculates the second target turning torque Tt2* based on the redundant target turning torque Ttj*. The second target turning torque Tt2* is the torque generated from the second coil group 56 when the previous target turning torque Tty* or the redundant target turning torque Ttj* is generated in the turning side motor 32. According to the present embodiment, the second target turning torque calculation unit 105 calculates half value (50%) of the previous target turning torque Tty* or the redundant target turning torque Ttj* as the second target turning torque Tt2*.

[0095] In addition to the second target turning torque Tt2*, the rotation angle θt2 and the phase current values Iut2, Ivt2, and Iwt2 are input to the second turning side motor control signal calculation unit 106. Similar to the first turning side motor control signal calculation unit 96, the second turning side motor control signal calculation unit 106 calculates the d-axis current command value Idt2* on the d-axis and the q-axis current command value Iqt2* on the q-axis in the dq coordinate system based on the second target turning torque Tt2*. Similar to the first turning side motor control signal calculation unit 96, the second turning side motor control signal calculation unit 106 calculates the second turning side motor control signal Mt2 by performing current F / B control in the dq coordinate system (i.e., based on the execution of current F / B control in the dq coordinate system). The q-axis current value Iqt2 calculated during the calculation of the second turning side motor control signal Mt2 is output to the target reaction torque calculation unit 72.

[0096] The calculated second turning side motor control signal Mt2 is output to the second turning side drive circuit 68. Therefore, drive power corresponding to the second turning side motor control signal Mt2 is supplied from the second turning side drive circuit 68 to the turning side motor 32. The motor torque indicated by the second target turning torque Tt2* is generated from the second coil group 56, and rotational force is applied from the turning side motor 32 to the turning wheel 5.

[0097] The configuration of the previous target turning torque calculation unit 94 will be described below. As Figure 6As shown, the previous target turning torque calculation unit 94 calculates the previous target turning torque Tty* based on performing angle control for adjusting the first turning corresponding angle θp1 to the first target turning corresponding angle θp1*. According to the present embodiment, the previous target turning torque calculation unit 94 performs, as the angle control: an F / B control for making the first turning corresponding angle θp1 coincide with the first target turning corresponding angle θp1*, a feedforward control based on the first target turning corresponding angle θp1*, and a damping control based on the first turning corresponding angular velocity ωp1, which is the rate of change of the first turning corresponding angle θp1. The previous target turning torque calculation unit 94 changes the control gain for performing the angle control based on the brake operation flag Fbr, the vehicle speed Vb, the lateral acceleration γ, the object temperature Temp, and the first state signal S1, i.e., the drive mode of the turning side motor 32. Therefore, optimization of the angle control is achieved. In the following description, the term "feedforward" may be referred to as "F / F".

[0098] Here, as the vehicle speed Vb increases, the torque required to turn the turning wheel 5 increases. Therefore, the degree to which the first turning corresponding angle θp1 is adjusted to the first target turning corresponding angle θp1* by the execution of the angle control changes with the change in the vehicle speed Vb, and the behavior of the vehicle in response to steering is affected.

[0099] When the vehicle is in a decelerating state, the center of gravity of the vehicle moves forward, and thus the stability coefficient may have a negative value, and the vehicle may oversteer. That is, the behavior of the vehicle in response to steering is affected by the change in the acceleration - deceleration state of the vehicle. The stability coefficient is a value based on the difference between the load acting on the front wheels and the load acting on the rear wheels. According to the present embodiment, the previous target turning torque calculation unit 94 determines that the vehicle is in a decelerating state when the brake operation flag Fbr indicating that the brake is operated is input, and determines that the vehicle is not in a decelerating state (i.e., the vehicle is in a non - decelerating state) when the brake operation flag Fbr indicating that the brake is operated is not input.

[0100] As the lateral acceleration γ increases, the torque required to turn the turning wheel 5 increases. Therefore, the degree to which the first turning corresponding angle θp1 is adjusted to the first target turning corresponding angle θp1* by the execution of the angle control changes with the change in the lateral acceleration γ, and the behavior of the vehicle in response to steering is affected.

[0101] Here, for example, as the object temperature Temp decreases, the viscosity of the grease in the turning side motor 32 increases, and thus a greater torque needs to be generated to operate the turning side motor 32. Therefore, the degree to which the first turning corresponding angle θp1 is adjusted toward the first target turning corresponding angle θp1* by the execution of the angle control changes with the change in the object temperature Temp, and the behavior of the vehicle in response to steering is affected.

[0102] When the drive mode of the turning side motor 32 indicated by the first state signal S1 changes, even when the q-axis current command value Iqt1* remains the same, the rotation angle θt1 of the turning side motor 32 is different. That is, the device characteristics (i.e., transfer function) of the system are different depending on the drive mode of the turning side motor 32, where the q-axis current command value Iqt* is the input and the rotation angle θt1 is the output. In the present embodiment, in the order of the independent mode, the cooperative mode, and the remaining mode, it is less likely to generate a large motor torque (the possibility of generating a large motor torque is reduced). When the device characteristics change in this way, for example, the degree to which the first turning corresponding angle θp1 is adjusted toward the first target turning corresponding angle θp1* changes with the change in the object temperature Temp, and the behavior of the vehicle in response to steering is affected.

[0103] That is, the acceleration-deceleration state of the vehicle, the vehicle speed Vb, the lateral acceleration γ, the object temperature Temp, and the drive mode of the turning side motor 32 correspond to factors that affect the behavior of the vehicle in response to steering. Specifically, the previous target turning torque calculation unit 94 includes: an angle F / B torque calculation unit 111 that calculates the angle F / B torque Tfbp, an angle F / F torque calculation unit 112 that calculates the angle F / F torque Tffp, and a damping torque calculation unit 113 that calculates the damping torque Tdmp. The previous target turning torque calculation unit 94 calculates the value obtained by summing the angle F / F torque Tffp, the angle F / B torque Tfbp, and the damping torque Tdmp as the target turning torque Tt*.

[0104] In addition to the angle difference Δθp1 obtained by subtracting the first turning corresponding angle θp1 from the first target turning corresponding angle θp1* by the subtractor 114, the brake operation flag Fbr, the vehicle speed Vb, the lateral acceleration γ, the object temperature Temp, and the first state signal S1 are also input to the angle F / B torque calculation unit 111. The angle F / B torque calculation unit 111 calculates the angle F / B torque Tfbp by performing angle F / B control as will be described later based on the state quantity. The calculated angle F / B torque Tfbp is output to the adder 115.

[0105] In addition to the first target turning corresponding angle θp1*, the brake operation flag Fbr, vehicle speed Vb, lateral acceleration γ, object temperature Temp, and the first state signal S1 are also input to the angle F / F torque calculation unit 112. The angle F / F torque calculation unit 112 calculates the angle F / F torque Tffp by performing angle F / F control as described later based on the state quantities. The calculated angle F / F torque Tffp is output to the adder 115.

[0106] In addition to the first turning corresponding angular velocity ωp1 obtained by differentiating the first turning corresponding angle θp1, the brake operation flag Fbr, vehicle speed Vb, lateral acceleration γ, object temperature Temp, and the first state signal S1 are also input to the damping torque calculation unit 113. The damping torque calculation unit 113 calculates the damping torque Tdmp by performing damping control as described later based on the state quantities. The calculated damping torque Tdmp is output to the adder 115.

[0107] The previous target turning torque calculation unit 94 calculates the previous target turning torque Tty* by causing the adder 115 to add the angle F / F torque Tffp, the angle F / B torque Tfbp, and the damping torque Tdmp.

[0108] The configuration of the angle F / B torque calculation unit 111 will be described below. As Figure 7 shown, the angle F / B torque calculation unit 111 calculates the angle F / B torque Tfbp by performing PID control as the angle F / B control.

[0109] Specifically, the angle F / B torque calculation unit 111 includes a proportional component calculation unit 121 that calculates the proportional component Tp, an integral component calculation unit 122 that calculates the integral component Ti, and a derivative component calculation unit 123 that calculates the derivative component Td. The proportional component Tp calculated by the proportional component calculation unit 121 is output to the adder 124. The integral component Ti calculated by the integral component calculation unit 122 is output to the adder 124. The derivative component Td calculated by the derivative component calculation unit 123 is output to the adder 124. The angle F / B torque calculation unit 111 calculates the angle F / B torque Tfbp by causing the adder 124 to add the proportional component Tp, the integral component Ti, and the derivative component Td. The proportional component calculation unit 121, the integral component calculation unit 122, and the derivative component calculation unit 123 will be described in sequence below.

[0110] Proportional component calculation unit 121

[0111] In addition to the angle difference Δθp1, the brake operation flag Fbr, vehicle speed Vb, lateral acceleration γ, target temperature Temp, and first state signal S1 are also input to the proportional component calculation unit 121. The proportional component calculation unit 121 calculates the proportional component Tp by multiplying the angle difference Δθp1 by the proportional gain Kp, where the proportional gain Kp is a control gain and F / B gain based on the brake operation flag Fbr, vehicle speed Vb, lateral acceleration γ, target temperature Temp, and first state signal S1.

[0112] Specifically, the proportional component calculation unit 121 includes a proportional gain calculation unit 131 that calculates the proportional gain Kp. The brake operation flag Fbr, vehicle speed Vb, lateral acceleration γ, target temperature Temp, and first state signal S1 are input to the proportional gain calculation unit 131. The proportional gain calculation unit 131 calculates the proportional gain Kp based on the brake operation flag Fbr, vehicle speed Vb, lateral acceleration γ, target temperature Temp, and first state signal S1, and outputs the calculated proportional gain Kp to the multiplier 132. In addition to the proportional gain Kp, the angle difference Δθp1 is input to the multiplier 132. The proportional component calculation unit 121 calculates the proportional component Tp by causing the multiplier 132 to multiply the angle difference Δθp1 by the proportional gain Kp. The calculated proportional component Tp is output to the adder 124.

[0113] As Figure 8 shown, the proportional gain calculation unit 131 includes a normal vehicle speed response gain calculation unit 141 that calculates the normal vehicle speed response gain Kvn, a deceleration vehicle speed response gain calculation unit 142 that calculates the deceleration vehicle speed response gain Kvr, and an output switching unit 143. The proportional gain calculation unit 131 also includes a drive mode response gain calculation unit 144 that calculates the drive mode response gain Kmo, a lateral acceleration response gain calculation unit 145 that calculates the lateral acceleration response gain Kγ, and a target temperature response gain calculation unit 146 that calculates the target temperature response gain Ktemp. The proportional gain calculation unit 131 calculates the proportional gain Kp by multiplying the proportional base gain Kpb by one of the normal vehicle speed response gain Kvn, deceleration vehicle speed response gain Kvr, drive mode response gain Kmo, lateral acceleration response gain Kγ, and target temperature response gain Ktemp.

[0114] The vehicle speed Vb is input to the normal vehicle speed response gain calculation unit 141. The normal vehicle speed response gain calculation unit 141 includes a map that defines the relationship between the vehicle speed Vb and the normal vehicle speed response gain Kvn. The normal vehicle speed response gain calculation unit 141 refers to the map to calculate the normal vehicle speed response gain Kvn corresponding to the vehicle speed Vb. In the map, when the vehicle speed Vb is zero, the normal vehicle speed response gain Kvn is set to have a value greater than zero. In the map, the normal vehicle speed response gain Kvn is set to increase linearly as the absolute value of the vehicle speed Vb increases. The calculated normal vehicle speed response gain Kvn is output to the output switching unit 143.

[0115] The vehicle speed Vb is input to the deceleration vehicle speed response gain calculation unit 142. The deceleration vehicle speed response gain calculation unit 142 includes a map that defines the relationship between the vehicle speed Vb and the deceleration vehicle speed response gain Kvr. The deceleration vehicle speed response gain calculation unit 142 refers to the map to calculate the deceleration vehicle speed response gain Kvr corresponding to the vehicle speed Vb. In the map, when the vehicle speed Vb is zero, the deceleration vehicle speed response gain Kvr is set to have a value greater than zero. In the map, the deceleration vehicle speed response gain Kvr is set to increase linearly as the absolute value of the vehicle speed Vb increases. The deceleration vehicle speed response gain Kvr is set to be smaller than the normal vehicle speed response gain Kvn at any vehicle speed Vb. The calculated deceleration vehicle speed response gain Kvr is output to the output switching unit 143.

[0116] The normal vehicle speed response gain Kvn, the deceleration vehicle speed response gain Kvr, and the brake operation flag Fbr are input to the output switching unit 143. When the brake operation flag Fbr indicating that the brake is operated is not input, the output switching unit 143 outputs the normal vehicle speed response gain Kvn to the multiplier 147. On the other hand, when the brake operation flag Fbr indicating that the brake is operated is input, the output switching unit 143 outputs the deceleration vehicle speed response gain Kvr to the multiplier 147. That is, the proportional gain calculation unit 131 reduces the proportional gain Kp by outputting a deceleration vehicle speed response gain Kvr smaller than the normal vehicle speed response gain Kvn when the vehicle is in a deceleration state.

[0117] The first state signal S1 is input to the drive mode response gain calculation unit 144. The drive mode response gain calculation unit 144 calculates the drive mode response gain Kmo corresponding to the drive mode indicated by the first state signal S1. In the drive mode response gain calculation unit 144, the drive mode response gain Kmo corresponding to the drive mode is preset. The drive mode response gain Kmo is set to increase in the order of the independent mode, the cooperative mode, and the remaining mode. The calculated drive mode response gain Kmo is output to the multiplier 147.

[0118] The lateral acceleration γ is input to the lateral acceleration response gain calculation unit 145. The lateral acceleration response gain calculation unit 145 includes a map that defines the relationship between the lateral acceleration γ and the lateral acceleration response gain Kγ. The lateral acceleration response gain calculation unit 145 refers to the map to calculate the lateral acceleration response gain Kγ corresponding to the lateral acceleration γ. In the map, when the lateral acceleration is zero, the lateral acceleration response gain Kγ is set to have a value greater than zero. In the map, the lateral acceleration response gain Kγ is set to increase linearly as the absolute value of the lateral acceleration γ increases. The calculated lateral acceleration response gain Kγ is output to the multiplier 147.

[0119] The object temperature Temp is input to the object temperature response gain calculation unit 146. The object temperature response gain calculation unit 146 includes a map that defines the relationship between the object temperature Temp and the object temperature response gain Ktemp. The object temperature response gain calculation unit 146 refers to the map to calculate the object temperature response gain Ktemp corresponding to the object temperature Temp. In the map, when the object temperature Temp is zero, the object temperature response gain Ktemp is set to have a value greater than zero. In the map, the object temperature response gain Ktemp is set to increase linearly as the object temperature Temp decreases. The calculated object temperature response gain Ktemp is output to the multiplier 147.

[0120] In addition to one of the normal vehicle speed response gain Kvn, the deceleration vehicle speed response gain Kvr, the drive mode response gain Kmo, the lateral acceleration response gain Kγ, and the object temperature response gain Ktemp, the proportional base gain Kpb, which is a preset constant, is input to the multiplier 147. The proportional gain calculation unit 131 calculates the proportional gain Kp by causing the multiplier 147 to multiply the proportional base gain Kpb by one of the normal vehicle speed response gain Kvn, the deceleration vehicle speed response gain Kvr, the drive mode response gain Kmo, the lateral acceleration response gain Kγ, and the object temperature response gain Ktemp. The calculated proportional gain Kp is output to Figure 7 the multiplier 132 shown in

[0121] the integral component calculation unit 122

[0122] as Figure 7As shown, in addition to the angle difference Δθp1, the brake operation flag Fbr, vehicle speed Vb, lateral acceleration γ, object temperature Temp, and first state signal S1 are input to the integral component calculation unit 122. The integral component calculation unit 122 calculates the integral basic component Tib by multiplying the angle difference Δθp1 by the integral gain Ki, which is a control gain and F / B gain based on the brake operation flag Fbr, vehicle speed Vb, lateral acceleration γ, object temperature Temp, and first state signal S1. The integral component calculation unit 122 calculates the integral component Ti by adding the integral value, which is obtained by integrating the value of the integral basic component Tib calculated up to the previous operation cycle, to the integral basic component Tib calculated in the latest operation cycle.

[0123] Specifically, the integral component calculation unit 122 includes an integral gain calculation unit 133 that calculates the integral gain Ki. The brake operation flag Fbr, vehicle speed Vb, lateral acceleration γ, object temperature Temp, and first state signal S1 are input to the integral gain calculation unit 133. The integral gain calculation unit 133 calculates the integral gain Ki based on the brake operation flag Fbr, vehicle speed Vb, lateral acceleration γ, object temperature Temp, and first state signal S1 and outputs the calculated integral gain Ki to the multiplier 134. In addition to the integral gain Ki, the angle difference Δθp1 is input to the multiplier 134. The integral component calculation unit 122 calculates the integral basic component Tib by causing the multiplier 134 to multiply the angle difference Δθp1 by the integral gain Ki. The calculated integral basic component Tib is output to the adder 135. In addition to the integral basic component Tib, the integral value obtained by integrating the value of the integral basic component Tib calculated up to the previous operation cycle is input to the adder 135. The integral component calculation unit 122 calculates the integral component Ti by causing the adder 135 to add the integral value and the integral basic component Tib.

[0124] Similar to the proportional gain calculation unit 131, the integral gain calculation unit 133 calculates the integral gain Ki. That is, the integral gain calculation unit 133 calculates the integral gain Ki by multiplying the integral basic gain Kib by one of the normal vehicle speed response gain Kvn, deceleration vehicle speed response gain Kvr, drive mode response gain Kmo, lateral acceleration response gain Kγ, and object temperature response gain Ktemp. The one of the normal vehicle speed response gain Kvn, deceleration vehicle speed response gain Kvr, drive mode response gain Kmo, lateral acceleration response gain Kγ, and object temperature response gain Ktemp that multiplies the integral basic gain Kib may have the same value as the gain that multiplies the proportional basic gain Kpb, or may have a different value from it.

[0125] Differential component calculation unit 123

[0126] In addition to the angular difference Δθp1, the brake operation flag Fbr, the vehicle speed Vb, the lateral acceleration γ, the object temperature Temp, and the first state signal S1 are input to the differential component calculation unit 123. The differential component calculation unit 123 calculates the differential component Td by multiplying the angular velocity difference Δωp1 obtained by differentiating the angular difference Δθp1 by a differential gain Kd, which is a control gain and an F / B gain corresponding to the brake operation flag Fbr, the vehicle speed Vb, the lateral acceleration γ, the object temperature Temp, and the first state signal S1.

[0127] Specifically, the differential component calculation unit 123 includes a differential gain calculation unit 136 that calculates the differential gain Kd. The brake operation flag Fbr, the vehicle speed Vb, the lateral acceleration γ, the object temperature Temp, and the first state signal S1 are input to the differential gain calculation unit 136. The differential gain calculation unit 136 calculates the differential gain Kd based on the brake operation flag Fbr, the vehicle speed Vb, the lateral acceleration γ, the object temperature Temp, and the first state signal S1 and outputs the calculated differential gain Kd to the multiplier 137. In addition to the differential gain Kd, the angular velocity difference Δωp1 is input to the multiplier 137. The differential component calculation unit 123 calculates the differential component Td by causing the multiplier 137 to multiply the angular velocity difference Δωp1 by the differential gain Kd.

[0128] Similar to the proportional gain calculation unit 131, the differential gain calculation unit 136 calculates the differential gain Kd. That is, the differential gain calculation unit 136 calculates the differential gain Kd by multiplying a differential base gain Kdb by one of a normal vehicle speed response gain Kvn, a deceleration vehicle speed response gain Kvr, a drive mode response gain Kmo, a lateral acceleration response gain Kγ, and an object temperature response gain Ktemp. The one of the normal vehicle speed response gain Kvn, the deceleration vehicle speed response gain Kvr, the drive mode response gain Kmo, the lateral acceleration response gain Kγ, and the object temperature response gain Ktemp that multiplies the differential base gain Kdb may have the same value as the gain that multiplies the proportional base gain Kpb, or may have a different value from it. The calculated differential gain Kd is output to the multiplier 137.

[0129] As described above, the angular F / B torque calculation unit 111 calculates the angular F / B torque Tfbp while changing the proportional gain Kp, the integral gain Ki, and the differential gain Kd based on factors that affect the behavior of the vehicle in response to steering.

[0130] The configuration of the angular F / F torque calculation unit 112 will be described below. As Figure 9As shown, the angle F / F torque calculation unit 112 includes an SAT component calculation unit 151 that calculates the SAT component Tsat, a device component calculation unit 152 that calculates the device component Tplt, and an angle F / F gain calculation unit 153 that calculates the angle F / F gain Kffp. The SAT component Tsat represents the torque for compensating the disturbance corresponding to the self-aligning torque applied to the turning wheel 5. The device component Tplt represents the torque for compensating the disturbance based on the device characteristics of the system, where the q-axis current command value Iqt1* for the turning side motor 32 is used as the input and the turning corresponding angle θp1 is used as the output. The angle F / F torque calculation unit 112 calculates the angle F / F torque Tffp by multiplying the angle F / F gain Kffp by the added value obtained by summing (adding) the SAT component Tsat and the device component Tplt.

[0131] Specifically, the first target turning corresponding angle θp1* is input to the SAT component calculation unit 151. The SAT component calculation unit 151 calculates the SAT component Tsat by multiplying the first target turning corresponding angle θp1* by a preset SAT coefficient. The SAT coefficient is a coefficient representing the relationship between the self-aligning torque applied to the turning wheel 5 and the first turning corresponding angle θp1, and the SAT coefficient is preset. The calculated SAT component Tsat is output to the adder 154.

[0132] The first target turning corresponding angle θp1* is input to the device component calculation unit 152. The device component calculation unit 152 calculates the output obtained by inputting the first target turning corresponding angle θp1* to a preset transfer function representing the device characteristics of the system as the device component Tplt. The calculated device component Tplt is output to the adder 154.

[0133] The brake operation flag Fbr, vehicle speed Vb, lateral acceleration γ, object temperature Temp, and first state signal S1 are input to the angle F / F gain calculation unit 153. Similar to the proportional gain calculation unit 131, the angle F / F gain calculation unit 153 calculates the angle F / F gain Kffp. That is, the angle F / F gain calculation unit 153 calculates the angle F / F gain Kffp by multiplying the F / F base gain Kffbp by one of the normal vehicle speed response gain Kvn, deceleration vehicle speed response gain Kvr, drive mode response gain Kmo, lateral acceleration response gain Kγ, and object temperature response gain Ktemp. The one of the normal vehicle speed response gain Kvn, deceleration vehicle speed response gain Kvr, drive mode response gain Kmo, lateral acceleration response gain Kγ, and object temperature response gain Ktemp that multiplies the F / F base gain Kffbp may have the same value as the gain that multiplies the proportional base gain Kpb, or may have a different value from it. The calculated angle F / F gain Kffp is output to the multiplier 155.

[0134] The angle F / F torque calculation unit 112 calculates the added value Affp by causing the adder 154 to sum (add) the SAT component Tsat and the device component Tplt. The calculated added value Affp is output to the multiplier 155. The angle F / F torque calculation unit 112 calculates the angle F / F torque Tffp by causing the multiplier 155 to multiply the added value Affp by the angle F / F gain Kffp. In this way, the angle F / F torque calculation unit 112 calculates the angle F / F torque Tffp while changing the angle F / F gain Kffp based on factors that affect the behavior of the vehicle in response to steering.

[0135] The configuration of the damping torque calculation unit 113 will be described below. As Figure 10 shown, the damping torque calculation unit 113 includes a damping base component calculation unit 161 that calculates the damping base component Tdmpb and a damping gain calculation unit 162 that calculates the damping gain Kdmp. The damping torque calculation unit 113 calculates the damping torque Tdmp by multiplying the damping base component Tdmpb by the damping gain Kdmp.

[0136] Specifically, the angular velocity ωp1 corresponding to the first turn is input to the damping base component calculation unit 161. The damping gain calculation unit 162 includes a map that defines the relationship between the angular velocity ωp1 corresponding to the first turn and the damping base component Tdmpb. The damping base component calculation unit 161 calculates the damping base component Tdmpb whose absolute value corresponds to the angular velocity ωp1 corresponding to the first turn with reference to this map. The damping base component calculation unit 161 sets the sign of the damping base component Tdmpb to the same sign as the sign of the angular velocity ωp1 corresponding to the first turn. In the map, when the angular velocity ωp1 corresponding to the first turn is zero, the damping base component Tdmpb is set to zero. In the map, the damping base component Tdmpb is set to increase as the absolute value of the angular velocity ωp1 corresponding to the first turn increases. The calculated damping base component Tdmpb is output to the multiplier 163.

[0137] The brake operation flag Fbr, vehicle speed Vb, lateral acceleration γ, object temperature Temp, and the first state signal S1 are input to the damping gain calculation unit 162. Similar to the proportional gain calculation unit 131, the damping gain calculation unit 162 calculates the damping gain Kdmp. That is, the damping gain calculation unit 162 calculates the damping gain Kdmp by multiplying the damping base gain Kdmpb by one of the normal vehicle speed response gain Kvn, deceleration vehicle speed response gain Kvr, drive mode response gain Kmo, lateral acceleration response gain Kγ, and object temperature response gain Ktemp. The one of the normal vehicle speed response gain Kvn, deceleration vehicle speed response gain Kvr, drive mode response gain Kmo, lateral acceleration response gain Kγ, and object temperature response gain Ktemp that multiplies the damping base gain Kdmpb may have the same value as the gain that multiplies the proportional base gain Kpb, or may have a different value from it. The calculated damping gain Kdmp is output to the multiplier 163.

[0138] The damping torque calculation unit 113 calculates the damping torque Tdmp by causing the multiplier 163 to multiply the damping base component Tdmpb by the damping gain Kdmp. In this way, the damping torque calculation unit 113 calculates the damping torque Tdmp while changing the damping gain Kdmp based on factors that affect the behavior of the vehicle in response to steering.

[0139] As described above, the previous target turning torque calculation unit 94 calculates the angle F / B torque Tfbp, angle F / F torque Tffp, and damping torque Tdmp by changing the control gain corresponding to factors that affect the behavior of the vehicle in response to steering, and calculates the previous target turning torque Tty* based on this. Therefore, optimization of angle control can be achieved.

[0140] Similar to the previous target turning torque calculation unit 94, the redundant target turning torque calculation unit 104 calculates a redundant target turning torque Ttj*. Therefore, optimization of angle control can be achieved. The functions and advantages of this embodiment will be described below.

[0141] (1) Each of the previous target turning torque calculation unit 94 and the redundant target turning torque calculation unit 104 changes a control gain for angle control based on a brake operation flag Fbr, a vehicle speed Vb, a lateral acceleration γ, an object temperature Temp, and a drive mode of the turning side motor 32. Therefore, angle control can be optimized according to factors that affect the behavior of the vehicle in response to steering, and optimization of the behavior of the vehicle in response to steering can be achieved.

[0142] (2) Since the previous target turning torque calculation unit 94 changes the control gain according to the drive mode of the turning side motor 32, angle control can be optimized and optimization of the behavior of the vehicle in response to steering can be achieved, even when the degree of adjustment of the first turning corresponding angle θp1 to the first target turning corresponding angle θp1* changes as the drive mode is changed due to the execution of angle control. Similarly, since the redundant target turning torque calculation unit 104 changes the control gain according to the drive mode of the turning side motor 32, angle control can be optimized and optimization of the behavior of the vehicle in response to steering can be achieved.

[0143] (3) Since each of the previous target turning torque calculation unit 94 and the redundant target turning torque calculation unit 104 increases the control gain in the order of an independent mode, a cooperative mode, and a remaining mode, optimal angle control can be performed according to the drive mode of the turning side motor 32.

[0144] (4) Since each of the previous target turning torque calculation unit 94 and the redundant target turning torque calculation unit 104 increases the control gain as the vehicle speed Vb increases, optimal angle control can be performed according to the vehicle speed Vb.

[0145] (5) Since each of the previous target turning torque calculation unit 94 and the redundant target turning torque calculation unit 104 changes the control gain such that the control gain when the vehicle is in a decelerated state is less than the control gain when the vehicle is in a non-decelerated state, oversteering can be suppressed and an improvement in the steering feel can be achieved.

[0146] (6) Since each of the previous target turning torque calculation unit 94 and the redundant target turning torque calculation unit 104 increases the control gain as the absolute value of the lateral acceleration γ increases, optimal angle control can be performed according to the lateral acceleration γ.

[0147] (7) Since each of the previous target turning torque calculation unit 94 and the redundant target turning torque calculation unit 104 increases the control gain as the object temperature Temp decreases, the optimal angle control can be performed according to the object temperature Temp.

[0148] (8) The previous target turning torque calculation unit 94 performs angle control: angle F / B control for making the first turning corresponding angle θp1 conform to the first target turning corresponding angle θp1*, angle F / F control based on the first target turning corresponding angle θp1*, and damping control based on the first turning corresponding angular velocity ωp1, which is the change rate of the first turning corresponding angle θp1. The control gains changed based on the brake operation flag Fbr, vehicle speed Vb, lateral acceleration γ, object temperature Temp, and drive mode include the proportional gain Kp, integral gain Ki, derivative gain Kd, angle F / F gain Kffp, and damping gain Kdmp. Therefore, the first turning corresponding angle θp1 can be appropriately adjusted to the first target turning corresponding angle θp1*. Similarly, since the redundant target turning torque calculation unit 104 performs angle F / B control, angle F / F control, and damping control, the second turning corresponding angle θp2 can be appropriately adjusted to the second target turning corresponding angle θp2*.

[0149] This embodiment can be modified as follows. Unless there is a technical contradiction, the embodiment and the following modification examples can be combined. In the embodiment, the turning side motor 32 includes the first coil group 55 and the second coil group 56, but the present invention is not limited thereto. For example, the turning side actuator 31 may include a plurality of turning side motors. This configuration is equivalent to a configuration in which a motor that applies motor torque to the steering device includes a plurality of coil groups having different power supply paths.

[0150] In the foregoing embodiment, the turning side motor 32 may include a plurality of coil groups having three or more different power supply paths, and the steering control device 1 may include groups each having a turning side microcomputer and a turning side drive circuit, such that the number of these groups is the same as the number of coil groups. The turning side motor 32 may include only one coil group, and the steering control device 1 may include only one group having a turning side microcomputer and a turning side drive circuit. That is, the configuration for applying motor torque to the turning unit 6 may not be redundant.

[0151] In the foregoing embodiment, the steering side motor 13 may include a plurality of coil groups having two or more different power supply paths, and the steering control device 1 may include groups each having a steering side microcomputer and a steering side drive circuit, such that the number of these groups is the same as the number of coil groups.

[0152] In the foregoing embodiment, the angular axial force calculation unit 85 may calculate the angular axial force Fib using the second turning corresponding angle θp2 instead of the first turning corresponding angle θp1. In the foregoing embodiment, a mode other than the cooperative mode, the independent mode, and the remaining mode may be adopted as the drive mode of the turning side motor 32. For example, a drive mode may be adopted in which the absolute value of the q-axis current command value Iqt1* and the absolute value of the q-axis current command value Iqt2* are limited to suppress overheating of the turning side motor 32 when the temperature of the turning side motor 32 is equal to or higher than a threshold value.

[0153] In the foregoing embodiment, the temperature of the turning side motor 32 detected by the temperature sensor 46 is used as the target temperature Temp, but the present invention is not limited thereto. For example, the estimated temperature of the turning side motor 32 estimated based on the q-axis current value Iqt may be used as the target temperature. Instead of the temperature of the turning side motor 32, one or more other temperatures such as the temperature of the first turning side microcomputer 64, the temperature of the second turning side microcomputer 67, the temperature of the first turning side drive circuit 65, the temperature of the second turning side drive circuit 68, the temperature of the steering device 2, and / or the ambient temperature around the steering device 2 may be used as the target temperature.

[0154] In the above embodiment, the abnormality detection method performed by the first state management unit 93 and the second state management unit 103 may be appropriately modified. In the foregoing embodiment, when the vehicle is in a deceleration state, the control gain is reduced by outputting a deceleration vehicle speed response gain Kvr that is smaller than the normal vehicle speed response gain Kvn. However, the present invention is not limited thereto, and for example, the control gain may be reduced by outputting a deceleration response gain that varies according to whether the vehicle is in a deceleration state to the multiplier 147, and the calculation method may be appropriately modified.

[0155] In the foregoing embodiment, it is determined whether the vehicle is in a deceleration state based on the brake operation flag Fbr, but the present invention is not limited thereto. For example, the longitudinal acceleration in the longitudinal direction of the vehicle (i.e., the front-rear direction of the vehicle) may be detected, and when the longitudinal acceleration is less than a preset threshold value, it may be determined that the vehicle is in a deceleration state.

[0156] In the foregoing embodiment, the input torque base component calculation unit 81 may calculate the input torque base component Tb based on, for example, the steering torque Th and the vehicle speed Vb. In this case, the input torque base component calculation unit 81 calculates, for example, an input torque base component Tb whose absolute value increases as the vehicle speed Vb decreases.

[0157] In the foregoing embodiment, the execution mode of the angle control can be appropriately modified. For example, at least one of the angle F / F control and the damping control may not be executed. In the foregoing embodiment, the angle F / B torque calculation unit 111 executes PID control as the angle F / B control, but the present invention is not limited thereto, and for example, PI control may be executed. The execution mode of the angle F / B control can be appropriately modified.

[0158] In the foregoing embodiment, the angle F / F torque calculation unit 112 may calculate the angle F / F torque Tffp based on only one of the SAT component Tsat and the device component Tplt.

[0159] In the foregoing embodiment, the proportional gain Kp, the integral gain Ki, the derivative gain Kd, the angle F / F gain Kffp, and the damping gain Kdmp are changed based on the brake operation flag Fbr, the vehicle speed Vb, the lateral acceleration γ, the target temperature Temp, and the drive mode of the turning side motor 32, but the present invention is not limited thereto. As long as at least one of the control gains among the control gains is changed based on the brake operation flag Fbr, the vehicle speed Vb, the lateral acceleration γ, the target temperature Temp, and the drive mode, the other control gains may not be changed based on the brake operation flag Fbr, the vehicle speed Vb, the lateral acceleration γ, the target temperature Temp, and the drive mode.

[0160] In the foregoing embodiment, the proportional gain Kp is changed based on the brake operation flag Fbr, the vehicle speed Vb, the lateral acceleration γ, the target temperature Temp, and the drive mode of the turning side motor 32. However, the proportional gain Kp may not be changed based on all of the brake operation flag Fbr, the vehicle speed Vb, the lateral acceleration γ, the target temperature Temp, and the driving mode, and the proportional gain Kp may be changed based on at least one of the brake operation flag Fbr, the vehicle speed Vb, the lateral acceleration γ, the target temperature Temp, and the driving mode. The same applies to the integral gain Ki, the derivative gain Kd, the angle F / F gain Kffp, and the damping gain Kdmp.

[0161] In the foregoing embodiment, the target reaction torque calculation unit 72 may calculate the target reaction torque Ts* based on executing angle control for adjusting the steering angle θh to the target steering angle, and the control gains for this angle control may be changed similarly to the control gains for the angle control performed by each of the previous target turning torque calculation unit 94 and the redundant target turning torque calculation unit 104.

[0162] In the foregoing embodiment, an interior permanent magnet synchronous motor (IPMSM) may be used as the steering-side motor 13. The interior permanent magnet synchronous motor may be used as the steering-side motor 32. In the foregoing embodiment, the steering device 2 to be controlled has a disconnected structure in which the power transmission between the steering unit 4 and the turning unit 6 is cut off, but the present invention is not limited thereto. A steering device having a structure in which the power transmission between the steering unit 4 and the turning unit 6 can be cut off by a clutch may be employed.

[0163] In the foregoing embodiment, the steering device 2 (i.e., the control target) to be controlled is a steer-by-wire steering device, but the present invention is not limited thereto. For example, an electric power steering device to which motor torque is applied as an auxiliary force may be employed as the control target.

[0164] In the foregoing embodiment, the steering control device 1 is not limited to a steering control device that includes a CPU and a memory and executes software processing. For example, a dedicated hardware circuit (e.g., an ASIC) that executes at least some of the software processing executed in the foregoing embodiment may be provided. That is, the steering control device may have at least one of the following configurations (a) to (c). (a) A processor that executes all processing according to a program and a program storage device such as a ROM that stores the program are provided. (b) A processor that executes some processing according to a program, a program storage device, and a dedicated hardware circuit that executes other processing are provided. (c) A dedicated hardware circuit that executes all processing is provided. Here, the number of software processing circuits each including a processor and a program storage device or the number of dedicated hardware circuits may be two or more. That is, the processing may be executed by a processing circuit including at least one of the following: i) one or more software processing circuits; and ii) one or more dedicated hardware circuits.

[0165] Technical concepts that can be understood according to the embodiments and modification examples will be supplemented below: (1) A steering control device, in which the steering device has the following structure: In this structure, the power transmission between the steering unit and the turning unit that turns the turning wheels according to the steering input of the steering unit is cut off, and the motor is a turning-side motor that applies motor torque as a turning force for turning the turning wheels.

Claims

1. A steering control device configured to control a steering device (2) to which motor torque is applied from an actuator having a motor as a drive source, the steering control device being characterized by comprising: A control unit configured to output a motor control signal for controlling the operation of the motor; And A drive circuit configured to supply drive power to the motor based on the motor control signal, Wherein the control unit is configured to: Calculate a torque command value as a target value of the motor torque based on the execution of angle control for adjusting a convertible angle that can be converted into the rotation angle of the motor to a target angle; Calculate the motor control signal based on the torque command value; and Change a control gain for the angle control based on a change in a factor that affects the behavior of the vehicle in response to steering, The motor includes a plurality of coil groups having different power supply paths; A plurality of sets each including the control unit and the drive circuit are arranged such that the sets respectively correspond to the coil groups, and the number of the sets is the same as the number of the coil groups; A plurality of control systems are provided between the motor and the steering control device, and the control systems are configured to individually control the torque generated by the coil groups; and The factor includes the drive mode of the motor, The drive mode includes: A cooperation mode in which the torque generated by the coil groups of the respective control systems is controlled based on the torque command value calculated by the control unit of one of the plurality of control systems; An independent mode in which the torque generated by each coil group in the coil groups corresponding to the respective control systems is controlled based on the torque command values respectively calculated by the control units of the plurality of control systems; and A remaining mode in which, when one of the control systems is abnormal, the torque generated by the coil groups of the remaining control systems in the control systems is controlled based on the torque command value calculated by the control unit of the normal remaining control systems in the control systems; and The control gain is changed such that the control gain increases in the order of the independent mode, the cooperation mode, and the remaining mode.

2. The steering control device according to claim 1, characterized in that: The factor includes the vehicle speed; and The control gain is changed such that the control gain increases as the vehicle speed increases.

3. The steering control device according to claim 1, characterized in that: The factor includes the acceleration-deceleration state of the vehicle; and The control gain is changed to be smaller when the vehicle is in a deceleration state than when the vehicle is in a non-deceleration state.

4. The steering control device according to claim 1, characterized in that: The factor includes lateral acceleration; and The control gain is changed such that the control gain increases as the absolute value of the lateral acceleration increases.

5. The steering control device according to claim 1, characterized in that: The factor includes at least one object temperature among the temperature of the motor, the temperature of the control unit, the temperature of the drive circuit, the temperature of the steering device (2), and the ambient temperature around the steering device (2); and The control gain is changed such that the control gain increases as the object temperature decreases.

6. The steering control device according to claim 1, characterized in that: The angle control includes feedback control for making the convertible angle conform to the target angle; and The control gain includes a feedback gain for the feedback control.

7. The steering control device according to claim 1, characterized in that: The angle control includes a feedforward control based on the target angle; and The control gain includes a feedforward gain for the feedforward control.

8. The steering control device according to claim 1, wherein: The angle control includes a damping control based on a target angular velocity that is a rate of change of the target angle; and The control gain includes a damping gain for the damping control.

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