Steering Controls

Abstract

A steering control device is configured to control a motor that is a source of driving force provided to a steering mechanism of a vehicle. The steering control device includes a controller (75; 72; 53a; 62; 63a; 124; 133; 113a) configured to calculate a controlled variable based on a steering state, the controlled variable being used in the control of the motor. The controller (75; 72; 53a; 62; 63a; 124; 133; 113a) is configured to change a control parameter for the controller based on a command generated by a main control device according to an intervention purpose in steering control, the main control device being mounted on the vehicle.

Description

Technical Field

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

[0002] There is an electric power steering device (EPS) that applies the torque of a motor as an assist force to the steering mechanism of a vehicle. In recent years, the development of an autonomous driving system has been actively carried out, which can realize various driving assistance functions for improving the safety or convenience of the vehicle or an autonomous driving function for the system to perform driving instead of the driver. The control device of the autonomous driving system evaluates the optimal control method based on the state of the vehicle at that time, and commands the control device of the on-board system to perform separate control according to the evaluated control method. The control device of the EPS controls the drive of the motor based on the command value generated by the control device of the autonomous driving system.

[0003] For example, the control device of the EPS described in Japanese Unexamined Patent Application Publication No. 2015-33942 (JP 2015-33942A) generates an assist command for generating an assist torque for reducing the steering load based on the detection value of the steering torque. In addition, the control device of the EPS obtains a target value of a physical quantity related to steering generated by the autonomous driving system, and generates a follow-up command for generating an automatic steering torque that causes the detection value of the physical quantity to follow the target value. Then, the control device of the EPS drives the motor that generates the assist torque and the automatic steering torque based on the added value of the assist command and the follow-up command. The control device of the EPS changes the responsiveness of the target following control based on the degree of intervention of the driver in the following control and the degree of intervention of the autonomous driving system in the assist control.

[0004] Therefore, for example, when the intervention of the driver is detected while the target following control with high responsiveness is being executed, the intervention of the driver can be easily achieved by reducing the responsiveness of the target following control. Conversely, when the intervention of the automatic driving system is detected while the auxiliary control with low responsiveness is being executed, the responsiveness required for the target following control can be ensured by increasing the responsiveness of the target following control. Therefore, when the driver or the automatic driving system intervenes in the control currently being executed, the control can be switched without giving the driver a strange feeling. Summary of the invention

[0005] As the content of the steering control performed by the control device, there are various contents, including the target following control in JP2015-33942A. Therefore, the control device of the EPS is required to have more appropriate control characteristics depending on the content of the steering control. For example, from the viewpoint of performing the steering control more quickly, higher responsiveness is desired. In addition, from the viewpoint of enhancing quietness, lower responsiveness is desired. That is, responsiveness and quietness have a so-called trade-off (contradiction) relationship. Therefore, for example, in the case where the control device of the EPS has a steering control function requiring responsiveness and a steering control function requiring quietness, it is difficult to achieve control characteristics that are suitable for both steering control functions at the same time.

[0006] The control device of a so-called steer-by-wire steering device in which the power transmission between the steering wheel and the steering wheels is separated also has the same problem as the control device of the EPS. The present invention provides a steering control device that enables more appropriate control characteristics to be obtained according to the control content.

[0007] A steering control device according to an aspect of the present invention is configured to control a motor that is a source of driving force provided to a steering mechanism of a vehicle. The steering control device includes a controller configured to calculate a controlled variable according to a steering state, the controlled variable being used in the control of the motor. The controller is configured to change a control parameter for the controller based on a command generated by a main control device according to an intervention purpose in steering control, the main control device being mounted on the vehicle.

[0008] With the steering control device according to this aspect of the invention, the control parameters for the controller are changed according to the purpose of intervention of the main control device on the steering control. Therefore, appropriate control characteristics can be obtained according to the purpose of intervention of the main control device on the steering control.

[0009] In the steering control device according to the aspect of the invention, the controller may be configured to calculate the controlled variable by performing feedback control to cause a detection value of a physical quantity that changes according to an action of the steering mechanism to follow a target value of the physical quantity.

[0010] With the steering control device according to this aspect of the invention, since the control parameter for the controller is changed according to the purpose of intervention of the main control device with respect to the steering control, the responsiveness of the feedback control with respect to the physical quantity that changes according to the action of the steering mechanism is changed. Therefore, more appropriate responsiveness according to the purpose of intervention of the main control device can be obtained as the responsiveness of the feedback control with respect to the physical quantity that changes according to the action of the steering mechanism.

[0011] The steering control device according to this aspect of the invention can be configured to control a motor including a steering motor that generates a steering force for rotating a steering wheel as a driving force provided to a steering shaft of a steering mechanism. The steering shaft can be configured to rotate the steering wheel. The power transmission between the steering wheel and the steering wheel can be separated. The controller can be configured to calculate a controlled variable by performing feedback control that causes a detected value of a physical quantity to follow a target value of the physical quantity, the physical quantity changing according to the steering action of the steering wheel.

[0012] With the steering control device according to this aspect of the invention, since the control parameter for the controller is changed according to the intervention purpose of the main control device for the steering control, the responsiveness of the feedback control for the physical quantity that changes according to the steering action of the steering wheel is changed. Therefore, more appropriate responsiveness according to the intervention purpose of the main control device can be obtained as the responsiveness of the feedback control for the physical quantity that changes according to the steering action of the steering wheel. In addition, more appropriate steering control characteristics according to the intervention purpose of the main control device can be obtained.

[0013] In the steering control device according to this aspect of the invention, the controller can be configured to calculate the controlled variable by performing at least one of feedback control in which a detected value of a current follows a target value of the current and feedback control in which a detected value of a rotation angle of a shaft follows a target value of the rotation angle of the shaft, the current being supplied to a steering motor that rotates according to the steering action of the steering wheel.

[0014] With the steering control device according to this aspect of the invention, since the control parameter for the controller is changed according to the purpose of intervention of the main control device with respect to the steering control, the responsiveness of at least one of the feedback control of the current supplied to the steering motor and the feedback control of the rotation angle of the shaft rotated according to the steering action of the steering wheel is changed. Therefore, more appropriate responsiveness according to the purpose of intervention of the main control device with respect to the steering control can be obtained as the responsiveness of the feedback control for at least one of the current supplied to the steering motor and the rotation angle of the shaft rotated according to the steering action of the steering wheel. In addition, more appropriate steering control characteristics according to the purpose of intervention of the main control device can be obtained.

[0015] The steering control device according to this aspect of the invention can be configured to control a motor, which includes a reaction motor that generates a steering reaction force as a driving force provided to a steering shaft of a steering mechanism. The steering shaft can be configured to rotate in conjunction with the operation of a steering wheel. The power transmission between the steering wheel and the steering shaft can be separated. The steering reaction force can be a torque in the opposite direction of the steering direction. The controller can be configured to calculate a controlled variable by performing feedback control that causes a detected value of a physical quantity to follow a target value of the physical quantity, and the physical quantity changes according to the operation of the steering wheel.

[0016] With the steering control device according to this aspect of the invention, since the control parameter for the controller is changed according to the purpose of intervention of the main control device with respect to the steering control, the responsiveness of the feedback control with respect to the physical quantity that changes according to the operation of the steering wheel is changed. Therefore, more appropriate responsiveness according to the purpose of intervention of the main control device with respect to the steering control can be obtained as the responsiveness of the feedback control with respect to the physical quantity that changes according to the operation of the steering wheel. In addition, more appropriate steering reaction force control characteristics according to the purpose of intervention of the main control device with respect to the steering control can be obtained.

[0017] In the steering control device according to this aspect of the invention, the controller can be configured to calculate the controlled variable by performing at least one of feedback control in which a detected value of the current follows a target value of the current and feedback control in which a detected value of the rotation angle of the steering shaft follows a target value of the rotation angle of the steering shaft, and the current is supplied to the reaction motor.

[0018] With the steering control device according to this aspect of the invention, since the control parameter for the controller is changed according to the purpose of intervention of the main control device with respect to the steering control, the responsiveness of at least one of the feedback control of the current supplied to the reaction motor and the feedback control of the rotation angle of the steering shaft is changed. Therefore, more appropriate responsiveness according to the purpose of intervention of the main control device with respect to the steering control can be obtained as the responsiveness of the feedback control for at least one of the current supplied to the reaction motor and the rotation angle of the steering shaft. In addition, more appropriate steering reaction force control characteristics according to the purpose of intervention of the main control device with respect to the steering control can be obtained.

[0019] The steering control device according to this aspect of the invention may be configured to control an auxiliary motor that generates a steering assist force as a driving force provided to a steering shaft or shaft of a steering mechanism. The shaft may be configured to rotate in conjunction with the operation of a steering wheel. The steering shaft may be configured to rotate a steering wheel in conjunction with the rotation of the shaft. The steering assist force may be a torque in the same direction as the steering direction. The controller may be configured to calculate a controlled variable by performing feedback control that causes a detected value of a physical quantity to follow a target value of the physical quantity, the physical quantity changing according to the operation of the steering wheel.

[0020] With the steering control device according to this aspect of the invention, since the control parameter for the controller is changed according to the intervention purpose of the main control device for the steering control, the responsiveness of the feedback control for the physical quantity that changes according to the operation of the steering wheel is changed. Therefore, more appropriate responsiveness according to the intervention purpose of the main control device can be obtained as the responsiveness of the feedback control for the physical quantity that changes according to the operation of the steering wheel. In addition, more appropriate steering assist control characteristics according to the intervention purpose of the main control device can be obtained.

[0021] In the steering control device according to this aspect of the invention, the controller can be configured to calculate the controlled variable by performing at least one of feedback control in which the detected value of the current follows the target value of the current and feedback control in which the detected value of the rotation angle of the shaft follows the target value of the rotation angle of the shaft, the current is supplied to the auxiliary motor, and the shaft rotates in conjunction with the operation of the steering wheel.

[0022] With the steering control device according to this aspect of the invention, since the control parameter for the controller is changed according to the purpose of intervention of the main control device with respect to the steering control, the responsiveness of at least one of the feedback control of the current supplied to the auxiliary motor and the feedback control of the rotation angle of the shaft rotating in conjunction with the operation of the steering wheel is changed. Therefore, more appropriate responsiveness according to the purpose of intervention of the main control device with respect to the steering control can be obtained as the responsiveness of the feedback control for at least one of the current supplied to the auxiliary motor and the rotation angle of the shaft rotating in conjunction with the operation of the steering wheel. In addition, more appropriate steering assist control characteristics according to the purpose of intervention of the main control device can be obtained.

[0023] With the steering control device according to this aspect of the invention, more appropriate control characteristics can be obtained according to the control content. 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 numerals represent like elements, and in which:

[0025] Figure 1is a configuration diagram of a steer-by-wire steering device equipped with a first embodiment of a steering control device;

[0026] Figure 2 is a control block diagram of a first embodiment of a steering control device;

[0027] Figure 3 is a control block diagram of a steering reaction force command value calculation unit in the first embodiment;

[0028] Figure 4 is a control block diagram of a steering angle feedback control unit in the first embodiment (third to sixth embodiments);

[0029] Figure 5 is a control block diagram of a steering angle feedback control unit in the second embodiment (third to sixth embodiments); and

[0030] Figure 6 This is a control block diagram of a seventh embodiment in which the steering control device is applied to an electric power steering device. DETAILED DESCRIPTION

[0031] First embodiment

[0032] A first embodiment in which the steering control device is applied to a steer-by-wire steering device will be described below.

[0033] like Figure 1 As shown, the steering device 10 of the vehicle includes a steering shaft 12 connected to a steering wheel 11. The steering shaft 12 constitutes a steering mechanism. In addition, the steering device 10 includes a plurality of Figure 1 The steering shaft 14 extends in the left and right directions (in the left and right directions). The left and right steering wheels 16 are respectively connected to both ends of the steering shaft 14 through the tie rods 15. The steering angle θw of the steering wheel 16 is changed by the linear movement of the steering shaft 14.

[0034] Configuration for generating steering reaction force: Reaction unit

[0035] The steering device 10 includes a reaction motor 31, a speed reducer 32, a rotation angle sensor 33, and a torque sensor 34 as a configuration for generating a steering reaction force. Incidentally, the steering reaction force is a force (torque) acting in the opposite direction to the direction in which the driver operates the steering wheel 11. By providing the steering reaction force to the steering wheel 11, the driver can feel an appropriate amount of reaction force (which can give the driver an appropriate road feel).

[0036] The reaction motor 31 is a source of the steering reaction force. For example, a brushless motor having three phases (U, V, and W) is used as the reaction motor 31. The reaction motor 31 (more precisely, the rotating shaft of the reaction motor 31) is connected to the steering shaft 12 through a speed reducer 32. The speed reducer 32 is provided at a portion on the steering shaft 12 that is closer to the steering wheel 11 than the clutch 21. The torque of the reaction motor 31 is provided to the steering shaft 12 as the steering reaction force.

[0037] The rotation angle sensor 33 is provided on the reaction motor 31. The rotation angle sensor 33 detects the rotation angle θa of the reaction motor 31, and the rotation angle θa of the reaction motor 31 is used to calculate the steering angle (steering angle) θs. The reaction motor 31 and the steering shaft 12 are interlocked with each other through the speed reducer 32. Therefore, the rotation angle θa of the reaction motor 31 has a correlation with the rotation angle of the steering shaft 12 and further with the steering angle θs (i.e., the rotation angle of the steering wheel 11). Therefore, the steering angle θs can be estimated based on the rotation angle θa of the reaction motor 31.

[0038] The torque sensor 34 detects the steering torque Th applied to the steering shaft 12 by the rotation operation of the steering wheel 11. The torque sensor 34 is provided at a portion on the steering shaft 12 and closer to the steering wheel 11 than the speed reducer 32.

[0039] Configuration for generating steering force: Steering unit

[0040] The steering device 10 includes a steering motor 41 , a speed reducer 42 , and a rotation angle sensor 43 as a configuration for generating a steering force, that is, a power for turning the steering wheel 16 .

[0041] The steering motor 41 is a source of steering force. For example, a brushless motor with three phases is used as the steering motor 41. The steering motor 41 (more precisely, the rotating shaft of the steering motor 41) is connected to the pinion shaft 44 through the reducer 42. The pinion 44a of the pinion shaft 44 is meshed with the rack 14b of the steering shaft 14. The torque of the steering motor 41 is provided to the steering shaft 14 as a steering force through the pinion shaft 44. In response to the rotation of the steering motor 41, the steering shaft 14 moves along the vehicle width direction (the left and right direction in the figure).

[0042] The rotation angle sensor 43 is provided on the steering motor 41. The rotation angle sensor 43 detects the rotation angle θb of the steering motor 41. Incidentally, the steering device 10 includes a pinion shaft 13. The pinion shaft 13 is arranged to intersect with the steering shaft 14. The pinion 13a of the pinion shaft 13 meshes with the rack 14a of the steering shaft 14. The reason for providing the pinion shaft 13 is that the pinion shaft 13 supports the steering shaft 14 together with the pinion shaft 44 in a housing (not shown). That is, by a supporting mechanism (not shown) provided in the steering device 10, the steering shaft 14 is supported so that the steering shaft 14 can move along the axial direction of the steering shaft 14 and be pressed toward the pinion shafts 13, 44. Thus, the steering shaft 14 is supported in the housing. However, another supporting mechanism that supports the steering shaft 14 in the housing without using the pinion shaft 13 may be provided.

[0043] Controls

[0044] The steering device 10 includes a control device 50. The control device 50 controls the reaction motor 31 and the steering motor 41 based on the detection results of various sensors. Regarding the sensors, in addition to the above-mentioned rotation angle sensor 33, torque sensor 34, and rotation angle sensor 43, there is a vehicle speed sensor 501. The vehicle speed sensor 501 provided in the vehicle detects a vehicle speed V, which is a running speed of the vehicle.

[0045] The control device 50 performs reaction force control by driving control of the reaction motor 31 to generate a steering reaction force corresponding to the steering torque Th. The control device 50 calculates a target steering reaction force based on the steering torque Th and the vehicle speed V, and calculates a target steering angle of the steering wheel 11 based on the calculated target steering reaction force, the steering torque Th and the vehicle speed V. The control device 50 calculates a steering angle correction amount by feedback control of the steering angle θs (the feedback control is performed so that the actual steering angle θs follows the target steering angle), and calculates a steering reaction force command value by adding the calculated steering angle correction amount to the target steering reaction force. The control device 50 supplies the reaction motor 31 with a current required to generate a steering reaction force corresponding to the steering reaction force command value.

[0046] The control device 50 performs steering control for rotating the steering wheel 16 by driving control of the steering motor 41 according to the rotation state. The control device 50 calculates the pinion angle θp, which is the actual rotation angle of the pinion shaft 44, based on the rotation angle θb of the steering motor 41 detected by the rotation angle sensor 43. The pinion angle θp is a value reflecting the steering angle θw of the steering wheel 16. The control device 50 calculates the target pinion angle using the above-mentioned target steering angle. Then, the control device 50 evaluates the deviation between the target pinion angle and the actual pinion angle θp, and controls the power supply to the steering motor 41 to eliminate the deviation.

[0047] The vehicle may be equipped with an automatic driving system that implements various driving assistance functions for improving the safety or convenience of the vehicle or an automatic driving function that enables the system to perform driving instead of the driver. In this case, in the vehicle, cooperative control is performed by the control device 50 and the control device of another vehicle-mounted system. Cooperative control is a technology in which the control devices of multiple vehicle-mounted systems cooperate with each other to control the vehicle's actions. For example, the vehicle is equipped with a main control device 500 that performs overall control of the control devices of various vehicle-mounted systems. The main control device 500 evaluates the optimal control method based on the vehicle state at the time, and commands the vehicle-mounted control device to perform various controls according to the evaluated control method.

[0048] The main control device 500 intervenes in the steering control of the control device 50. The main control device 500 switches the automatic driving control function of the main control device 500 between an on state (enabled) and an off state (disabled) by operating a switch not shown provided at the driver's seat or the like. In recent years, there are various driving assistances. In the present embodiment, the driving assistance is classified into a first driving assistance and a second driving assistance based on the difference in control characteristics required by the control device 50. For example, the first driving assistance includes lane departure prevention assistance, collision avoidance assistance, etc. The second driving assistance includes parking assistance, etc. In the control for performing the first driving assistance, responsiveness (following performance) is required as a control characteristic. In the control for performing the second driving assistance, quietness is required as a control characteristic.

[0049] The main control device 500 calculates each command value for the driving assistance content, and generates a final command value S* by adding each command value. In the present embodiment, the main control device 500 calculates a command value S1* for performing the first driving assistance and a command value S2* for performing the second driving assistance, and generates a final command value S* by adding the command values ​​S1* and S2*. Each of the command values ​​S1*, S2*, and S* is an additional angle command value. The additional angle command value is a target value of the steering angle (the angle that needs to be added to the current steering angle) required for the vehicle to travel along the target lane according to the driving state at the time. The control device 50 uses the command value S* calculated by the main control device 500 to control the reaction motor 31 and the steering motor 41.

[0050] The main control device 500 generates a mark as a command Sr1, Sr2 for the control device 50 for each driving assistance content. The command Sr1 is information indicating whether the first driving assistance control function is in an on state or in an off state. The command Sr2 is information indicating whether the second driving assistance control function is in an on state or in an off state. When the first driving assistance control function and the second driving assistance control function are in an on state, the main control device 500 sets the value of the mark as the command Sr1, Sr2 to "1". When the first driving assistance control function and the second driving assistance control function are in an off state, the main control device 500 sets the value of the mark as the command Sr1, Sr2 to "0".

[0051] Detailed configuration of the control device

[0052] Next, the control device 50 will be described in detail. Figure 2 As shown, the control device 50 includes a reaction force control unit 50a that performs reaction force control and a steering control unit 50b that performs steering control.

[0053] Reaction force control unit

[0054] The reaction force control unit 50 a includes a steering angle calculation unit 51 , a steering reaction force command value calculation unit 52 , and an energization control unit 53 .

[0055] The steering angle calculation unit 51 calculates the steering angle θs of the steering wheel 11 based on the rotation angle θa of the reaction motor 31 detected by the rotation angle sensor 33. The steering reaction force command value calculation unit 52 calculates the steering reaction force command value T* based on the steering torque Th, the vehicle speed V and the steering angle θs. The larger the steering torque Th and the smaller the vehicle speed V, the larger the absolute value of the steering reaction force command value T* calculated by the steering reaction force command value calculation unit 52. Incidentally, the steering reaction force command value calculation unit 52 calculates the target steering angle θ* of the steering wheel 11 in the process of calculating the steering reaction force command value T*. The steering reaction force command value calculation unit 52 will be described in detail later.

[0056] The power-on control unit 53 supplies the reaction motor 31 with electric power corresponding to the steering reaction force command value T*. Specifically, the power-on control unit 53 calculates a current command value for the reaction motor 31 based on the steering reaction force command value T*. In addition, the power-on control unit 53 detects the value of the actual current Ia generated in the power supply path to the reaction motor 31 by means of a current sensor 54 provided on the power supply path to the reaction motor 31. The value of the current Ia is the actual current value supplied to the reaction motor 31. Then, the power-on control unit 53 evaluates the deviation between the current command value and the value of the actual current Ia, and controls the power supply to the reaction motor 31 so as to eliminate the deviation (feedback control of the current Ia). As a result, the reaction motor 31 generates a torque corresponding to the steering reaction force command value T*. The driver can feel an appropriate amount of road surface reaction force (the driver can be given an appropriate sense of the road).

[0057] Steering control unit

[0058] The steering control unit 50 b includes a pinion angle calculation unit 61 , a pinion angle feedback control unit 62 , and an energization control unit 63 .

[0059] The pinion angle calculation unit 61 calculates the pinion angle θp, which is the actual rotation angle of the pinion shaft 44, based on the rotation angle θb of the steering motor 41 detected by the rotation angle sensor 43. The steering motor 41 and the pinion shaft 44 are interlocked with each other through the reducer 42. Therefore, there is a correlation between the rotation angle θb of the steering motor 41 and the pinion angle θp. By using this correlation, the pinion angle θp can be evaluated based on the rotation angle θb of the steering motor 41. In addition, the pinion shaft 44 is meshed with the steering shaft 14. Therefore, there is a correlation between the movement amount of the steering shaft 14 and the pinion angle θp. That is, the pinion angle θp is a value reflecting the rotation angle θw of the steering wheel 16.

[0060] The pinion angle feedback control unit 62 adopts the target steering angle θ* calculated by the steering reaction force command value calculation unit 52 as the target pinion angle θp*. In addition, the pinion angle feedback control unit 62 adopts the actual pinion angle θp calculated by the pinion angle calculation unit 61. The pinion angle feedback control unit 62 calculates the pinion angle command value Tp* by feedback control of the pinion angle θp so that the actual pinion angle θp follows the target pinion angle θp* (which is equal to the target steering angle θ* in the present embodiment).

[0061] The power-on control unit 63 supplies the steering motor 41 with power corresponding to the pinion angle command value Tp*. Specifically, the power-on control unit 63 calculates the current command value for the steering motor 41 based on the pinion angle command value Tp*. In addition, the power-on control unit 63 detects the value of the actual current Ib generated in the power supply path to the steering motor 41 through a current sensor 64 provided on the power supply path to the steering motor 41. The value of the current Ib is the actual current value supplied to the steering motor 41. Then, the power-on control unit 63 evaluates the deviation between the current command value and the value of the actual current Ib, and controls the power supply to the steering motor 41 so as to eliminate the deviation (feedback control of the current value Ib). As a result, the steering motor 41 rotates by an angle corresponding to the pinion angle command value Tp*.

[0062] Steering reaction force command value calculation unit

[0063] Next, the steering reaction force command value calculation unit 52 will be described in detail. Figure 3 As shown, the steering reaction force command value calculation unit 52 includes an adder 70, a target steering torque calculation unit 71, a torque feedback control unit 72, an axial force calculation unit 73, a target steering angle calculation unit 74, a steering angle feedback control unit 75 and an adder 76.

[0064] The adder 70 calculates the input torque Tin* as the torque applied to the steering shaft 12 by adding the steering torque Th detected by the torque sensor 34 and the first steering reaction force command value T1 * calculated by the torque feedback control unit 72 .

[0065] The target steering torque calculation unit 71 calculates the target steering torque Th* based on the input torque Tin* calculated by the adder 70. The target steering torque Th* is a target value of the steering torque Th that needs to be applied to the steering wheel 11. The greater the absolute value of the input torque Tin*, the greater the absolute value of the target steering torque Th* calculated by the target steering torque calculation unit 71.

[0066] The torque feedback control unit 72 uses the steering torque Th detected by the torque sensor 34 and the target steering torque Th* calculated by the target steering torque calculation unit 71. The torque feedback control unit 72 calculates the first steering reaction force command value T1* by feedback control of the steering torque Th so that the steering torque Th detected by the torque sensor 34 follows the target steering torque Th*.

[0067] The axial force calculation unit 73 adopts the target steering angle θ* calculated by the target steering angle calculation unit 74 as the target pinion angle θp*. In addition, the axial force calculation unit 73 adopts the value of the current Ib of the steering motor 41 detected by the current sensor 64 and the vehicle speed V detected by the vehicle speed sensor 501. The axial force calculation unit 73 calculates the axial force Fax acting on the steering shaft 14 through the steering wheel 16 based on the target pinion angle θp*, the value of the current Ib of the steering motor 41, and the vehicle speed V. Details are shown below.

[0068] The axial force calculation unit 73 calculates the ideal axial force F1, which is an ideal value of the axial force acting on the steering shaft 14 through the steering wheel 16, based on the target pinion angle θp*. The axial force calculation unit 73 calculates the ideal axial force F1 using an ideal axial force map stored in a storage device not shown of the control device 50. The greater the absolute value of the target pinion angle θp* (or the target steering angle obtained by multiplying the target pinion angle θp* by a predetermined conversion coefficient) and the lower the vehicle speed V, the greater the absolute value of the ideal axial force F1 is set. The vehicle speed V does not always have to be considered.

[0069] The axial force calculation unit 73 calculates the estimated axial force F2 acting on the steering shaft 14 based on the value of the current Ib of the steering motor 41. Here, a disturbance corresponding to the road surface state (frictional resistance of the road surface) acts on the steering wheel 16, and thereby generates a difference between the target pinion angle θp* and the actual pinion angle θp, thereby causing the value of the current Ib of the steering motor 41 to change. In other words, the value of the current Ib of the steering motor 41 reflects the actual road surface reaction force acting on the steering wheel 16. Therefore, the axial force reflecting the influence of the road surface state can be calculated based on the value of the current Ib of the steering motor 41. The estimated axial force F2 is evaluated by multiplying the value of the current Ib of the steering motor 41 by a gain (the gain is a coefficient according to the vehicle speed V).

[0070] The axial force calculation unit 73 individually sets the distribution ratio (gain) of the ideal axial force F1 and the distribution ratio of the estimated axial force F2. The axial force calculation unit 73 calculates the mixed axial force F3 by adding the values ​​obtained by multiplying the ideal axial force F1 and the estimated axial force F2 by the individually set distribution ratios. The distribution ratio is set according to various state variables reflecting vehicle behavior, road surface conditions, or steering conditions.

[0071] The target steering angle calculation unit 74 adopts the steering torque Th detected by the torque sensor 34, the first steering reaction force command value T1* calculated by the torque feedback control unit 72, the axial force Fax calculated by the axial force calculation unit 73, and the vehicle speed V detected by the vehicle speed sensor 501. The target steering angle calculation unit 74 calculates the target steering angle θ* of the steering wheel 11 based on the adopted steering torque Th, the first steering reaction force command value T1*, the axial force Fax, and the vehicle speed V. Details thereof are as follows.

[0072] The target steering angle calculation unit 74 estimates the final input torque Tin* of the steering wheel 11 by subtracting the torque conversion value (steering reaction force corresponding to the axial force) obtained by converting the axial force Fax into torque from the input torque Tin* (which is the sum of the first steering reaction force command value T1* and the steering torque Th). The target steering angle calculation unit 74 calculates the target steering angle θ* (target steering angle) from the final input torque Tin* based on an ideal model represented by the following expression (A). In this ideal model, the steering angle (steering angle) of the steering wheel 11 corresponding to the ideal steering angle depending on the input torque Tin* is modeled in advance by experiments or the like, on the premise of a steering device in which the steering wheel 11 is mechanically coupled to the steering wheel 16.

[0073] Tin*=Jθ*"+Cθ*'+Kθ*...(A)

[0074] Among them, "J" is the inertia coefficient corresponding to the inertia moment of the steering wheel 11 and the steering shaft 12, "C" is the viscosity coefficient (friction coefficient) corresponding to the friction between the steering shaft 14 and the housing, etc., and "K" is the spring modulus when each of the steering wheel 11 and the steering shaft 12 is regarded as a spring. The viscosity coefficient C and the inertia coefficient J are values ​​that depend on the vehicle speed V. In addition, "θ*"" is the second-order time differential value of the target steering angle θ*, and "θ*'" is the first-order time differential value of the target steering angle θ*.

[0075] Incidentally, in the case where the additional angle command value is calculated as the command value S* by executing driving assistance control or automatic driving control by the main control device 500, the command value S* is added to the target steering angle θ* calculated by the target steering angle calculation unit 74. The final target steering angle θ* after adding the command value S* is provided to each of the axial force calculation unit 73 and the steering angle feedback control unit 75.

[0076] The steering angle feedback control unit 75 uses the steering angle θs calculated by the steering angle calculation unit 51 and the target steering angle θ* calculated by the target steering angle calculation unit 74. The steering angle feedback control unit 75 calculates the second steering reaction force command value T2* by feedback control of the steering angle θs such that the actual steering angle θs calculated by the steering angle calculation unit 51 follows the target steering angle θ*.

[0077] The adder 76 calculates a steering reaction force command value T* by adding the first steering reaction force command value T1 * calculated by the torque feedback control unit 72 and the second steering reaction force command value T2 * calculated by the steering angle feedback control unit 75 .

[0078] Steering angle feedback control unit

[0079] Next, the steering angle feedback control unit 75 will be described in detail. In the present embodiment, the steering angle feedback control unit 75 performs proportional control as feedback control.

[0080] like Figure 4 As shown, the steering angle feedback control unit 75 includes a subtractor 81, two gradient processing units 82 and 83, two gain calculation units 84 and 85, and two multipliers 86 and 87. The constituent elements (81 to 87) constitute a proportional controller as a controller. The proportional controller calculates a manipulated variable having a value proportional to the difference between the target value and the current value. In the present embodiment, the target value is the target steering angle θ*, the current value is the steering angle θs, and the steering amount is the second steering reaction force command value T2*.

[0081] The subtractor 81 evaluates the difference δθ by subtracting the steering angle θs calculated by the steering angle calculation unit 51 from the target steering angle θ* calculated by the target steering angle calculation unit 74. The gradual change processing unit 82 adopts a flag according to the command Sr1 generated by the main control device 500. The gradual change processing unit 82 calculates the automatic driving rate DR1 by performing a gradual change process (a process of gradually changing a value) of the value of the flag as the command Sr1 with respect to time. The automatic driving rate DR1 corresponds to the command value S1* calculated by the main control device 500.

[0082] The gradual change processing unit 83 uses the flag of the command Sr2 generated by the main control device 500. The gradual change processing unit 83 calculates the automatic driving rate DR2 by performing a gradual change process of the value of the flag of the command Sr2 with respect to time. The automatic driving rate DR2 corresponds to the command value S2* calculated by the main control device 500.

[0083] By the way, the automatic driving rate is a value indicating the degree to which the system participates in the driving of the vehicle (in this embodiment, the degree to which the main control device 500 intervenes in the steering control). As the driving assistance system becomes more complex or sophisticated with the improvement of the technical level, the degree to which the system participates in driving increases. For example, when the automatic driving rate is "1 (100%)", the system completely performs driving instead of the driver. On the contrary, when the automatic driving rate is "0 (%)", the driver performs all driving environment recognition, danger judgment and driving operations of the vehicle (steering, acceleration, deceleration, etc.).

[0084] For example, one of the following two configurations (a1), (a2) is adopted as the gradation processing units 82, 83.

[0085] (a1) The gradual change processing units 82, 83 have a so-called change amount guard function with respect to time, which is a function of limiting the change amount of the value as a sign of the command Sr1, Sr2 per unit time to a predetermined limit value. The gradual change processing units 82, 83 can change the limit value according to the steering speed, the target steering speed, the steering torque, or the steering torque differential value.

[0086] (a2) A low-pass filter is used as the gradual change processing units 82 and 83. Each low-pass filter can change the cutoff frequency according to the steering speed, the target steering speed, the steering torque, or the steering torque differential value.

[0087] The gain calculation unit 84 calculates the gain G1 of the command value S1* calculated by the main control device 500 based on the automatic driving rate DR1 calculated by the gradual change processing unit 82. The gain G1 is calculated from the standpoint of adjusting the responsiveness of the first driving assist control according to the automatic driving rate DR1. For example, the larger the value of the automatic driving rate DR1, the larger the value of the gain G1 calculated by the gain calculation unit 84.

[0088] The gain calculation unit 85 calculates the gain G2 of the command value S2* calculated by the main control device 500 based on the automatic driving rate DR2 calculated by the gradient processing unit 83. The gain G2 is calculated from the standpoint of adjusting the responsiveness of the second driving assistance control according to the automatic driving rate DR2. For example, the larger the value of the automatic driving rate DR2, the smaller the value of the gain G2 calculated by the gain calculation unit 85.

[0089] The multiplier 86 multiplies the proportional gain Kp as a standard value stored in a not-shown storage device provided in the control device 50 by the gain G1 calculated by the gain calculation unit 84 and the gain G2 calculated by the gain calculation unit 85, thereby calculating a final proportional gain Kpf.

[0090] The multiplier 87 calculates a second steering reaction command value T2 * by multiplying the difference δθ calculated by the subtractor 81 by the final proportional gain Kpf calculated by the multiplier 86 .

[0091] Operation of the First Embodiment

[0092] Next, the operation of the first embodiment will be described. The responsiveness of the steering angle feedback control performed by the steering angle feedback control unit 75 increases as the value of the proportional gain Kp becomes larger, and decreases as the value of the proportional gain Kp becomes smaller. In addition, the quietness of the steering device 10 decreases as the responsiveness of the steering angle feedback control becomes higher, and increases as the responsiveness of the steering angle feedback control becomes lower.

[0093] When the first driving assistance control function is switched from the off state to the on state, the main control device 500 switches the value of the mark as the command Sr1 from "0" to "1". At this time, as the automatic driving rate DR1, the gradual processing unit 82 gradually changes the value of the mark as the command Sr1 from "0" to "1" based on "0.1", for example. As the automatic driving rate DR1 increases, the value of the gain G1 also gradually increases. Therefore, the value of the final proportional gain Kpf obtained by multiplying the proportional gain Kp as a standard value by the gain G1 also gradually increases. Therefore, compared with the case where the standard value is used as the proportional gain Kp, the responsiveness of the steering angle feedback control increases. In the first driving assistance, from the standpoint of ensuring higher safety, it is desired to more quickly reflect the command value S* calculated by the main control device 500 in the target steering angle θ*.

[0094] When the second driving assistance control function is switched from the off state to the on state, the main control device 500 switches the value of the mark serving as the command Sr2 from "0" to "1". At this time, as the automatic driving rate DR2, the gradient processing unit 83 gradually changes the value of the mark serving as the command Sr2 from "0" to "1" based on, for example, "0.1". As the automatic driving rate DR2 increases, the value of the gain G2 also gradually decreases. Therefore, the value of the final proportional gain Kpf obtained by multiplying the proportional gain Kp serving as a standard value by the gain G2 also gradually decreases. Therefore, the responsiveness of the steering angle feedback control is reduced compared to the case where the standard value is used as the proportional gain Kp. Due to the reduced responsiveness of the steering angle feedback control, the quietness of the steering device 10 increases.

[0095] Incidentally, it can be expected that the vehicle speed V at the time of parking is a very low speed. In addition, when parking, it is necessary to rotate the steering wheel 11 to a greater extent. Therefore, the reaction force of the road surface and the axial force acting on the steering shaft 14 may be large values. In addition, the value of the target steering angle θ* may be set to a large value, that is, the reaction motor 31 and the steering motor 41 need to generate a large torque, and therefore, sound and vibration are easily generated by actuating the reaction motor 31 and the steering motor 41. Therefore, when parking, the quietness of the steering device 10 may be required rather than the responsiveness of the steering angle feedback control.

[0096] Effects of the First Embodiment

[0097] Therefore, according to the first embodiment, the following effects can be obtained.

[0098] (1) The responsiveness of the feedback control in the control device 50 is changed according to the execution of the driving assistance. Specifically, the value of the proportional gain Kp as a control parameter for the steering angle feedback control unit 75 is set to an appropriate value according to the content of the driving assistance. Therefore, more appropriate control characteristics (responsiveness and quietness) can be obtained according to the content of the driving assistance control executed by the control device 50.

[0099] Incidentally, the axial force acting on the steering shaft 14 changes according to the vehicle speed V. In addition, the optimum value of the proportional gain Kp differs according to the magnitude of the axial force. From this point of view, it is also desirable to change the value of the proportional gain Kp according to different driving assistance contents within the expected vehicle speed range.

[0100] (2) When the automatic driving rates DR1, DR2 are switched between "0" and "1" immediately, although the value of the final proportional gain Kpf depends on the difference δθ, there is a concern that the value of the final proportional gain Kpf increases or decreases rapidly. In this regard, in this embodiment, when the first driving assist control function or the second driving assist control function is switched between the on state and the off state, the rapid change of the automatic driving rates DR1, DR2 is suppressed by performing the gradual change processing by the gradual change processing units 82, 83. Therefore, it is possible to suppress the rapid change of the second steering reaction force command value T2*, and thus suppress the rapid change of the steering reaction force provided to the steering wheel 11.

[0101] Second embodiment

[0102] Next, a second embodiment of the steering control device will be described. This embodiment is different from the first embodiment in the configuration of the steering angle feedback control unit 75 (proportional controller).

[0103] like Figure 5As shown, the steering angle feedback control unit 75 includes a single gain calculation unit 88 in addition to the subtractor 81 and the two multipliers 86 and 87. Figure 4 Each of the two gradient processing units 82, 83 and gain calculation units 84, 85 shown.

[0104] The gain calculation unit 88 includes table data 88a. The gain calculation unit 88 calculates the gain G3 by referring to the table data 88a. The table data 88a is information that specifies the correspondence between the values ​​("1" or "0") of the commands Sr1 and Sr2 and the gain G3. The gain calculation unit 88 sets the value of the gain G3 according to the values ​​of the commands Sr1 and Sr2. The details are as follows.

[0105] When the value of the flag as the command Sr1 is "1", that is, when the first driving assist control function is in the on state, the gain calculation unit 88 sets the gain G3 to the gain G3a. In addition, when the value of the flag as the command Sr2 is "1", that is, when the second driving assist control function is in the on state, the gain calculation unit 88 sets the gain G3 to the gain G3b. In addition, when each of the values ​​of the flags as the commands Sr1, Sr2 is "0", that is, when each of the first driving assist control function and the second driving assist control function is in the off state, the gain calculation unit 88 sets the gain G3 to the gain G3c.

[0106] From the perspective of adjusting the value of the proportional gain Kp for obtaining the control characteristics (responsiveness and quietness in this embodiment) required by the control device 50 when the control device 50 performs the first driving assistance control or the second driving assistance control, the values ​​of the three gains G3a, G3b, and G3c are set through experiments or simulations.

[0107] The gain G3a is set from the viewpoint of changing the value of the final proportional gain Kpf to a value larger than the standard value to increase the responsiveness of the steering angle feedback control. The gain G3b is set from the viewpoint of changing the value of the final proportional gain Kpf to a value smaller than the standard value to reduce the responsiveness of the steering angle feedback control. For example, the gain G3c is set from the viewpoint of maintaining the value of the final proportional gain Kpf at the standard value when there is no need to adjust the responsiveness of the steering angle feedback control. For example, the value of the gain G3c is set to "1". The magnitude relationship of the gains G3a, G3b, and G3c is expressed by the following expression (B).

[0108] G3a>G3c>G3b>0...(B)

[0109] When the gain calculation unit 88 calculates the gain G3a, the multiplier 86 multiplies the gain G3a by the proportional gain Kp as a standard value, thereby calculating a final proportional gain Kpf having a value larger than the standard value. When the gain calculation unit 88 calculates the gain G3b, the multiplier 86 multiplies the gain G3b by the proportional gain Kp as a standard value, thereby calculating a final proportional gain Kpf having a value smaller than the standard value. When the gain calculation unit 88 calculates the gain G3c, the multiplier 86 multiplies the gain G3c (in this embodiment, G3c=1) by the proportional gain Kp as a standard value, thereby calculating a final proportional gain Kpf having the same value as the standard value.

[0110] Therefore, with the second embodiment, the same effects as those described in (1) in the first embodiment can be obtained.

[0111] Third embodiment

[0112] Next, a third embodiment of the steering control device will be described. This embodiment is different from the first embodiment in the configuration of the torque feedback control unit 72.

[0113] The torque feedback control unit 72 has Figure 4 The steering angle feedback control unit 75 has the same configuration as shown. Figure 4 As shown in the reference numerals in brackets, the torque feedback control unit 72 adopts the commands Sr1, Sr2 generated by the main control device 500, and adjusts the proportional gain Kp according to the adopted commands Sr1, Sr2.

[0114] When the steering angle feedback control unit 75 adopts the target steering angle θ* and the steering angle θs, the torque feedback control unit 72 adopts the steering torque Th and the target steering torque Th* calculated by the target steering torque calculation unit 71. In addition, when the subtractor 81 of the steering angle feedback control unit 75 calculates the difference δθ between the target steering angle θ* and the steering angle θs, the subtractor 81 of the torque feedback control unit 72 calculates the difference δTh between the target steering torque Th* and the steering torque Th. The multiplier 87 of the torque feedback control unit 72 calculates the first steering reaction force command value T1* by multiplying the difference δTh between the target steering torque Th* and the steering torque Th by the final proportional gain Kpf adjusted according to the commands Sr1, Sr2.

[0115] Therefore, according to the third embodiment, in addition to the effects described in (1) and (2) in the first embodiment, the following effects can be obtained.

[0116] (3) The value of proportional gain Kp as a control parameter for torque feedback control unit 72 is set to an appropriate value according to the content of driving assistance. Therefore, more appropriate control characteristics (responsiveness and quietness) can be obtained according to the content of driving assistance control executed by control device 50.

[0117] Fourth embodiment

[0118] Next, a fourth embodiment of the steering control device will be described. This embodiment differs from the first embodiment in that Figure 2 The configuration of the power-on control unit 53 is shown.

[0119] The power-on control unit 53 includes a current command value calculation unit, a current feedback control unit, and a drive circuit (inverter circuit). The current command value calculation unit calculates a current command value for the reaction motor 31 based on the steering reaction force command value T*. The current command value is a current target value that needs to be provided to the reaction motor 31 and is required to generate a target steering reaction force of an appropriate size corresponding to the steering reaction force command value T*. The current feedback control unit generates a motor control signal by feedback control of the current Ia, and the feedback control of the current Ia makes the value of the actual current Ia detected by the current sensor 54 follow the current command value. The drive circuit provides the current corresponding to the motor control signal to the reaction motor 31. As a result, the reaction motor 31 generates a torque corresponding to the steering reaction force command value T*.

[0120] The current feedback control unit 53a has Figure 4 The steering angle feedback control unit 75 has the same configuration as shown. Figure 4 As shown in the reference numerals in brackets in , the current feedback control unit 53a adopts the commands Sr1, Sr2 generated by the main control device 500, and adjusts the proportional gain Kp according to the adopted commands Sr1, Sr2.

[0121] When the steering angle feedback control unit 75 adopts the target steering angle θ* and the steering angle θs, the current feedback control unit 53a adopts the value of the actual current Ia detected by the current sensor 54 and the current command value Ia* calculated by the current command value calculation unit. In addition, when the subtractor 81 of the steering angle feedback control unit 75 calculates the difference δθ between the target steering angle θ* and the steering angle θs, the subtractor 81 of the current feedback control unit 53a calculates the difference δIa between the current command value Ia* and the value of the actual current Ia. The multiplier 87 of the current feedback control unit 53a calculates the motor control signal Sa of the reaction motor 31 by multiplying the difference δIa between the current command value Ia* and the value of the actual current Ia by the final proportional gain Kpf adjusted according to the commands Sr1, Sr2.

[0122] Therefore, according to the fourth embodiment, in addition to the effects described in (1) and (2) of the first embodiment, the following effects can be obtained.

[0123] (4) The value of proportional gain Kp as a control parameter for current feedback control unit 53a is set to an appropriate value according to the content of driving assistance. Therefore, more appropriate control characteristics (responsiveness and quietness) can be obtained according to the content of driving assistance control performed by control device 50.

[0124] Fifth embodiment

[0125] Next, a fifth embodiment of the steering control device will be described. This embodiment differs from the first embodiment in that Figure 2 The configuration of the pinion angle feedback control unit 62 is shown.

[0126] The pinion angle feedback control unit 62 has Figure 4 The steering angle feedback control unit 75 has the same configuration as shown. Figure 4 As shown in the reference numerals in square brackets, the pinion angle feedback control unit 62 adopts the commands Sr1 and Sr2 generated by the main control device 500. The proportional gain Kp is adjusted according to the adopted commands Sr1 and Sr2.

[0127] When the steering angle feedback control unit 75 adopts the target steering angle θ* and the steering angle θs, the pinion angle feedback control unit 62 adopts the target steering angle θ* calculated by the steering reaction force command value calculation unit 52 as the target pinion angle θp*. In addition, the pinion angle feedback control unit 62 adopts the actual pinion angle θp calculated by the pinion angle calculation unit 61.

[0128] In addition, when the subtractor 81 of the steering angle feedback control unit 75 calculates the difference δθ between the target steering angle θ* and the steering angle θs, the subtractor 81 of the pinion angle feedback control unit 62 calculates the difference δθp between the target pinion angle θp* and the actual pinion angle θp. The multiplier 87 of the pinion angle feedback control unit 62 calculates the pinion angle command value Tp* by multiplying the difference δθp between the target pinion angle θp* and the actual pinion angle θp by the final proportional gain Kpf adjusted according to the commands Sr1, Sr2.

[0129] Therefore, according to the fifth embodiment, in addition to the effects described in (1) and (2) of the first embodiment, the following effects can be obtained.

[0130] (5) The value of proportional gain Kp as a control parameter for the pinion angle feedback control unit 62 is set to an appropriate value according to the content of driving assistance. Therefore, more appropriate control characteristics (responsiveness and quietness) can be obtained according to the content of driving assistance control performed by the control device 50.

[0131] Sixth Embodiment

[0132] Next, a sixth embodiment of the steering control device will be described. This embodiment differs from the first embodiment in that Figure 2 The configuration of the energization control unit 63 is shown.

[0133] The power-on control unit 63 includes a current command value calculation unit, a current feedback control unit, and a drive circuit (inverter circuit). The current command value calculation unit calculates a current command value for the steering motor 41 based on the pinion angle command value Tp*. The current command value is a current target value to be provided to the steering motor 41 and is required to achieve an appropriate steering angle θw corresponding to the pinion angle command value Tp*. The current feedback control unit generates a motor control signal through feedback control of the current Ib, and the feedback control of the current Ib makes the value of the actual current Ib detected by the current sensor 64 follow the current command value. The drive circuit provides the steering motor 41 with a current corresponding to the motor control signal. As a result, the steering motor 41 generates a torque corresponding to the pinion angle command value Tp*.

[0134] The current feedback control unit has Figure 4 The steering angle feedback control unit 75 has the same configuration as shown. Figure 4 As shown in the reference numerals in brackets, the current feedback control unit 63a adopts the commands Sr1, Sr2 generated by the main control device 500, and adjusts the proportional gain Kp according to the adopted commands Sr1, Sr2.

[0135] When the steering angle feedback control unit 75 adopts the target steering angle θ* and the steering angle θs, the current feedback control unit 63a adopts the value of the actual current Ib detected by the current sensor 64 and the current command value Ib* calculated by the current command value calculation unit. In addition, when the subtractor 81 of the steering angle feedback control unit 75 calculates the difference δθ between the target steering angle θ* and the steering angle θs, the subtractor 81 of the current feedback control unit 63a calculates the difference δIb between the current command value Ib* and the value of the actual current Ib. The multiplier 87 of the current feedback control unit 63a calculates the motor control signal Sb for the steering motor 41 by multiplying the difference δIb between the current command value Ib* and the value of the actual current Ib by the final proportional gain Kpf adjusted according to the commands Sr1, Sr2.

[0136] Therefore, according to the sixth embodiment, in addition to the effects described in (1) and (2) of the first embodiment, the following effects can be obtained.

[0137] (6) The value of proportional gain Kp as a control parameter for current feedback control unit 63a is set to an appropriate value according to the content of driving assistance. Therefore, more appropriate control characteristics (responsiveness and quietness) can be obtained according to the content of driving assistance control performed by control device 50.

[0138] Seventh embodiment

[0139] Next, a seventh embodiment will be described in which the steering control device is implemented as a control device for an electric power steering device (EPS). The same components as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions of these components are omitted.

[0140] In EPS, Figure 1 The steering wheel 11 and the steering wheel 16 are shown to be mechanically coupled to each other. That is, the steering shaft 12, the pinion shaft 13, and the steering shaft 14 serve as a power transmission path between the steering wheel 11 and the steering wheel 16. The steering shaft 14 moves linearly due to the rotation operation of the steering wheel 11, thereby changing the steering angle θw of the steering wheel 16. In addition, the EPS includes an auxiliary motor, which is provided at a position corresponding to the rotation operation of the steering wheel 11. Figure 1 The reaction motor 31 is shown at the same position as one of the steering motors 41. The assist motor generates a steering assist force (assist force).

[0141] like Figure 6 As shown, the control device 101 of the EPS 100 performs assist control to generate a steering assist force corresponding to the steering torque Th by controlling the energization of the assist motor 102. The control device 101 controls the power supply to the assist motor 102 based on the steering torque Th detected by the torque sensor 34, the vehicle speed V detected by the vehicle speed sensor 501, and the rotation angle θm detected by the rotation angle sensor 103 provided on the assist motor 102.

[0142] The control device 101 includes a pinion angle calculation unit 111, an assist command value calculation unit 112, and an energization control unit 113. The pinion angle calculation unit 111 adopts the rotation angle θm of the assist motor 102, and calculates the pinion angle θp, which is the rotation angle of the pinion shaft 13, based on the adopted rotation angle θm. The assist command value calculation unit 112 calculates the assist command value Tas* based on the steering torque Th and the vehicle speed V. The assist command value Tas* is a command value indicating the assist torque, which is the rotation force that needs to be generated by the assist motor 102. The energization control unit 113 supplies power corresponding to the assist command value Tas* to the assist motor 102. A current sensor 114 is provided on the power supply path to the assist motor 102. The current sensor 114 detects the value of the actual current Im supplied to the assist motor 102.

[0143] Next, the configuration of the assist command value calculation unit 112 will be described in detail. The assist command value calculation unit 112 includes a basic assist torque calculation unit 121, an axial force calculation unit 122, a target pinion angle calculation unit 123, a pinion angle feedback control unit (pinion angle F / B control unit) 124, and an adder 125.

[0144] The basic assist torque calculation unit 121 calculates the basic assist torque Tas1* based on the steering torque Th. The basic assist torque calculation unit 121 includes an adder 131, a target steering torque calculation unit 132, and a torque feedback control unit 133. The adder 131 calculates the input torque Tin* as the torque applied to the steering shaft 12 by adding the steering torque Th detected by the torque sensor 34 and the basic assist torque Tas1* calculated by the torque feedback control unit 133. The target steering torque calculation unit 132 calculates the target steering torque Th* based on the input torque Tin* calculated by the adder 131. The larger the absolute value of the input torque Tin* is, the larger the absolute value of the target steering torque Th* calculated by the target steering torque calculation unit 132 is. The torque feedback control unit 133 uses the steering torque Th detected by the torque sensor 34 and the target steering torque Th* calculated by the target steering torque calculation unit 132. The torque feedback control unit 133 calculates the basic assist torque Tas1 * by feedback control of the steering torque Th so that the steering torque Th detected by the torque sensor 34 follows the target steering torque Th*.

[0145] The axial force calculation unit 122 has Figure 3The axial force calculation unit 122 has the same function as the axial force calculation unit 73 in the first embodiment shown in the figure. The axial force calculation unit 122 uses the value of the current Im of the assist motor 102 detected by the current sensor 114, the target pinion angle θp* calculated by the target pinion angle calculation unit 123, and the vehicle speed V detected by the vehicle speed sensor 501. The axial force calculation unit 122 calculates the axial force Fax acting on the steering shaft 14 based on the value of the current Im of the assist motor 102, the target pinion angle θp*, and the vehicle speed V.

[0146] The target pinion angle calculation unit 123 has Figure 3 The target steering angle calculation unit 123 has the same function as the target steering angle calculation unit 74 in the first embodiment shown in the figure. The target pinion angle calculation unit 123 calculates the target pinion angle θp* based on the ideal model represented by the expression (A) using the basic assist torque Tas1* calculated by the basic assist torque calculation unit 121, the steering torque Th detected by the torque sensor 34, and the axial force Fax calculated by the axial force calculation unit 122.

[0147] The pinion angle feedback control unit 124 has Figure 3 The pinion angle feedback control unit 124 has the same function as the steering angle feedback control unit 75 in the first embodiment shown in the figure. The pinion angle feedback control unit 124 adopts the target pinion angle θp* calculated by the target pinion angle calculation unit 123 and the actual pinion angle θp calculated by the pinion angle calculation unit 111. The pinion angle feedback control unit 124 performs feedback control on the pinion angle θp so that the actual pinion angle θp follows the target pinion angle θp*. That is, the pinion angle feedback control unit 124 evaluates the deviation between the target pinion angle θp* and the actual pinion angle θp, and calculates the correction assist torque Tas2* as a correction component for the basic assist torque Tas1* to eliminate the deviation.

[0148] The adder 125 calculates the assist command value Tas* by adding the basic assist torque Tas1 * calculated by the basic assist torque calculation unit 121 and the correction assist torque Tas2 * calculated by the pinion angle feedback control unit 124 .

[0149] The energization control unit 113 calculates a current command value for the assist motor 102 based on the assist command value Tas*. In addition, the energization control unit 113 adopts the value of the current Im detected by the current sensor 114. Then, the energization control unit 113 evaluates the deviation between the current command value and the value of the actual current Im, and controls the power supply to the assist motor 102 to eliminate the deviation. As a result, the assist motor 102 generates a torque corresponding to the assist command value Tas*. That is, steering assist corresponding to the steering state is performed.

[0150] Pinion angle feedback control unit

[0151] The pinion angle feedback control unit 124 has Figure 4 The steering angle feedback control unit 75 has the same configuration as shown. Figure 4 As shown in the reference numerals in brackets, the pinion angle feedback control unit 124 adopts the commands Sr1, Sr2 generated by the main control device 500, and adjusts the proportional gain Kp according to the adopted Sr1, Sr2.

[0152] The steering angle feedback control unit 75 uses the target steering angle θ* and the steering angle θs, and the pinion angle feedback control unit 124 uses the target pinion angle θp* calculated by the target pinion angle calculation unit 123 and the actual pinion angle θp calculated by the pinion angle calculation unit 111 .

[0153] In addition, the subtractor 81 of the steering angle feedback control unit 75 calculates the difference δθ between the target steering angle θ* and the steering angle θs, and the subtractor 81 of the pinion angle feedback control unit 124 calculates the difference δθp between the target pinion angle θp* and the actual pinion angle θp. The multiplier 87 of the pinion angle feedback control unit 124 calculates the correction assist torque Tas2* by multiplying the difference δθp between the target pinion angle θp* and the actual pinion angle θp by the final proportional gain Kpf adjusted according to the commands Sr1 and Sr2.

[0154] Torque feedback control unit

[0155] The torque feedback control unit 133 has Figure 4 The steering angle feedback control unit 75 has the same configuration as shown. Figure 4 As shown in the reference numerals in brackets, the torque feedback control unit 133 adopts the commands Sr1, Sr2 generated by the main control device 500, and adjusts the proportional gain Kp according to the adopted commands Sr1, Sr2.

[0156] When the steering angle feedback control unit 75 adopts the target steering angle θ* and the steering angle θs, the torque feedback control unit 133 adopts the steering torque Th detected by the torque sensor 34 and the target steering torque Th* calculated by the target steering torque calculation unit 132. In addition, when the subtractor 81 of the steering angle feedback control unit 75 calculates the difference δθ between the target steering angle θ* and the steering angle θs, the subtractor 81 of the torque feedback control unit 133 calculates the difference δTh between the target steering torque Th* and the steering torque Th. The multiplier 87 of the torque feedback control unit 133 calculates the basic assist torque Tas1* by multiplying the difference δTh between the target steering torque Th* and the steering torque Th by the final proportional gain Kpf adjusted according to the commands Sr1, Sr2.

[0157] Power on control unit

[0158] The power-on control unit 113 includes a current command value calculation unit, a current feedback control unit, and a drive circuit (inverter circuit). The current command value calculation unit calculates a current command value for the assist motor 102 based on the assist command value Tas*. The current command value is a current target value that needs to be provided to the assist motor 102 and is required to generate a target assist force with an appropriate size corresponding to the assist command value Tas*. The current feedback control unit generates a motor control signal by feedback control of the current Im so that the value of the actual current Im detected by the current sensor 114 follows the current command value. The drive circuit provides the current corresponding to the motor control signal to the assist motor 102. As a result, the assist motor 102 generates a torque corresponding to the assist command value Tas*.

[0159] The current feedback control unit has Figure 4 The steering angle feedback control unit 75 has the same configuration as shown. Figure 4 As shown in the reference numerals in brackets, the current feedback control unit 113a adopts the commands Sr1 and Sr2 generated by the main control device 500, and adjusts the proportional gain Kp according to the adopted commands Sr1 and Sr2.

[0160] When the steering angle feedback control unit 75 adopts the target steering angle θ* and the steering angle θs, the current feedback control unit 113a adopts the value of the actual current Im detected by the current sensor 114 and the current command value Im* calculated by the current command value calculation unit. In addition, when the subtractor 81 of the steering angle feedback control unit 75 calculates the difference δθ between the target steering angle θ* and the steering angle θs, the subtractor 81 of the current feedback control unit 113a calculates the difference δIm between the current command value * and the value of the actual current Im. The multiplier 87 of the current feedback control unit 113a calculates the motor control signal Sm for the assist motor 102 by multiplying the difference δIm between the current command value Im* and the value of the actual current Im by the final proportional gain Kpf adjusted according to the commands Sr1, Sr2.

[0161] Therefore, with the seventh embodiment, in the steering device in which the power transmission between the steering wheel 11 and the steered wheels 16 is mechanically connected, in addition to the effects described in (1) and (2) in the first embodiment, the following effects can be obtained.

[0162] (7) The value of the proportional gain Kp as a control parameter for the pinion angle feedback control unit 62 is set to an appropriate value according to the content of the driving assistance. In addition, the value of the proportional gain Kp as a control parameter for the torque feedback control unit 133 is set to an appropriate value according to the content of the driving assistance. In addition, the value of the proportional gain Kp as a control parameter for the current feedback control unit 113a is set to an appropriate value according to the content of the driving assistance. Therefore, more appropriate control characteristics (responsiveness and quietness) can be obtained according to the content of the driving assistance control performed by the control device 50.

[0163] Other Implementations

[0164] The above-described embodiment may be performed while being modified as follows.

[0165] In the first embodiment, a configuration may be adopted in which the gradual change processing units 82, 83 are excluded from the steering angle feedback control unit 75. In this case, the values ​​of the commands Sr1, Sr2 are used as the automatic driving rates DR1, DR2 by the gain calculation units 84, 85. This is also true for the feedback control units in the third to seventh embodiments.

[0166] Figure 5 The second embodiment shown can be applied to the feedback control unit in the third to seventh embodiments.

[0167] In the first to seventh embodiments, the main control device 500 may generate the automatic driving rate as the command Sr1, Sr2 instead of generating a flag ("0" or "1"). In this case, after the gradual change processing of the gradual change processing units 82, 83, the automatic driving rate as the command Sr1, Sr2 is provided to the gain calculation units 84, 85.

[0168] In the first embodiment, in addition to the above-mentioned proportional control, the steering angle feedback control unit 75 can also perform at least one of integral control and differential control. Similar to the proportional gain Kp, the values ​​of the control parameters (integral gain Ki and differential gain Kd) for the integral control and the differential control are adjusted according to the commands Sr1, Sr2. This is also true for other feedback controllers as controllers other than the steering angle feedback control unit 75 in the first to seventh embodiments.

[0169] Incidentally, in the case where all of proportional control, integral control and differential control are executed by the controller including the steering angle feedback control unit 75, the manipulated variable u which is the operation amount of the control object for obtaining the target value is represented by the following expression (C).

[0170] u=Kp·ε+Ki·(integral value of ε)+Kd·ε'...(C))

[0171] Wherein "ε" is the deviation between the target value and the actual value, "ε'" is the differential value obtained by differentiating the deviation ε, "Kp" is the proportional gain, "Ki" is the integral gain, and "Kd" is the differential gain.

[0172] In addition to the proportional term, the integral term, and the differential term, at least one of a disturbance observer term, a dump term, and a feedforward term (F / F term) may be added to Expression (C).

[0173] In the first to sixth embodiments, the following configurations may be adopted as Figure 3 The steering reaction force command value calculation unit 52 shown in FIG. Figure 3 Instead of the target steering torque calculation unit 71 and the torque feedback control unit 72 shown in the figure, a target steering reaction force calculation unit is provided for calculating the first steering reaction force command value T1* as the target steering reaction force. For example, the target steering reaction force calculation unit does not use feedback control of the steering torque Th, but uses a three-dimensional map that specifies the relationship between the steering torque Th and the target steering reaction force according to the vehicle speed V to calculate the first steering reaction force command value T1* as the target steering reaction force.

[0174] Incidentally, the target steering reaction force calculation unit may adopt the axial force Fax of the steering shaft 14 calculated by the axial force calculation unit 73 in addition to the steering torque Th and the vehicle speed V, and may calculate the first steering reaction force command value T1* based on the adopted steering torque Th, the vehicle speed V and the axial force Fax. In addition, the target steering reaction force calculation unit may also adopt only the axial force Fax calculated by the axial force calculation unit 73 instead of the steering torque Th and the vehicle speed V, and may calculate the first steering reaction force command value T1* as the target steering reaction force based on the adopted axial force Fax.

[0175] In the seventh embodiment, the following configuration may be adopted as Figure 6 The basic assist torque calculation unit 121 shown. That is, the basic assist torque calculation unit 121 calculates the basic assist torque Tas1* using a three-dimensional map that specifies the relationship between the steering torque Th and the basic assist torque Tas1* according to the vehicle speed V, rather than using feedback control of the steering torque Th. The basic assist torque calculation unit 121 sets the absolute value of the basic assist torque Tas1* to be larger as the absolute value of the steering torque Th is larger and the vehicle speed V is lower.

[0176] In the first to sixth embodiments, a clutch may be provided in the steering device 10. In this case, Figure 1 As shown by the double-dotted line in FIG, the steering shaft 12 and the pinion shaft 13 are connected by a clutch 21. An electromagnetic clutch that connects and disconnects power by electrically connecting and disconnecting an excitation coil is used as the clutch 21. The control device 50 performs a connect-disconnect control to switch the clutch 21 between connection and disconnection. When the clutch 21 is disconnected, the power transmission between the steering wheel 11 and the steering wheel 16 is mechanically disconnected. When the clutch 21 is connected, the power transmission between the steering wheel 11 and the steering wheel 16 is mechanically connected.

Claims

1. A steering control device configured to control a motor, the motor being a source of driving force provided to a steering mechanism of a vehicle, the steering control device being characterized in that it includes a controller, the controller being provided at a subsequent stage of a target steering angle calculation unit that calculates a target steering angle of a steering wheel based on a steering torque, a first steering reaction force command value calculated by a torque feedback control unit, an axial force, and a vehicle speed, the controller being configured to calculate a controlled variable according to feedback control, the controlled variable being used in the control of the motor, the feedback control being performed based on a difference between a target value of a physical quantity and a detected value of the physical quantity, the physical quantity varying according to a final target steering angle, or an action of the steering mechanism based on the final target steering angle, the final target steering angle being calculated by adding a target steering angle calculated by the target steering angle calculation unit and an additional angle command value calculated by a main control device mounted on the vehicle performing driving assist control or automatic driving control, The controller is configured to modify a control parameter of the feedback control based on a command generated by a main control device according to a purpose of intervention in steering control, the main control device being mounted on the vehicle.

2. The steering control device according to claim 1, characterized in that: The steering control device is configured to control the motor, the motor includes a steering motor, the steering motor generates a steering force for turning a steering wheel as a driving force provided to a steering shaft of the steering mechanism, the steering shaft is configured to turn the steering wheel, and power transmission between a steering wheel and the steering wheel is disconnected; as well as The controller is configured to calculate the controlled variable by performing feedback control to cause a detection value of a physical quantity to follow a target value of the physical quantity, the physical quantity changing in accordance with a steering action of the steering wheel.

3. The steering control device according to claim 2, characterized in that: The controller is configured to calculate the controlled variable by performing at least one of feedback control for causing a detected value of a current to follow a target value of the current and feedback control for causing a detected value of a rotation angle of a shaft to follow a target value of the rotation angle of the shaft, the current being supplied to the steering motor and the shaft rotating according to a steering action of the steering wheel.

4. The steering control device according to claim 1, characterized in that: The steering control device is configured to control the motor, the motor includes a reaction motor, the reaction motor generates a steering reaction force as a driving force provided to a steering shaft of the steering mechanism, the steering shaft is configured to rotate in conjunction with the operation of the steering wheel, the power transmission between the steering wheel and the steering shaft is separated, and the steering reaction force is a torque in a direction opposite to the steering direction; as well as The controller is configured to calculate the controlled variable by performing feedback control that causes a detection value of a physical quantity to follow a target value of the physical quantity, the physical quantity changing according to an operation of the steering wheel.

5. The steering control device according to claim 4, characterized in that: The controller is configured to calculate the controlled variable by performing at least one of feedback control that causes a detected value of a current to follow a target value of the current and feedback control that causes a detected value of a rotation angle of a steering shaft to follow a target value of the rotation angle of the steering shaft, the current being supplied to the reaction motor.

6. The steering control device according to claim 1, characterized in that: The steering control device is configured to control an auxiliary motor, the auxiliary motor generates a steering assist force as a driving force provided to a steering shaft or a shaft of the steering mechanism, the shaft being configured to rotate in conjunction with the operation of the steering wheel, the steering shaft being configured to turn the steering wheel in conjunction with the rotation of the shaft, the steering assist force being a torque in the same direction as the steering direction; as well as The controller is configured to calculate the controlled variable by performing feedback control that causes a detection value of a physical quantity to follow a target value of the physical quantity, the physical quantity changing according to an operation of the steering wheel.

7. The steering control device according to claim 6, characterized in that: The controller is configured to calculate the controlled variable by performing at least one of feedback control that causes a detected value of a current to follow a target value of the current and feedback control that causes a detected value of a rotation angle of a shaft to follow a target value of the rotation angle of the shaft, the current being supplied to the auxiliary motor and the shaft rotating in conjunction with an operation of the steering wheel.

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