Steering control device and standard value adjustment method

Abstract

A steering operation control device and a standard value adjustment method are disclosed. A steering operation control device (1) includes a control unit (60). The control unit (60) is configured to execute a control angle calculation process, an angle feedback process, and a standard value adjustment process. The control angle calculation process is a process of calculating a control angle that is an absolute angle with respect to a standard value, and the angle feedback process is a process of performing feedback control on the control angle, and the standard value adjustment process is a process of adjusting a stored standard value. The standard value adjustment process includes a process of adjusting the standard value so that a deviation of the control angle from a value indicating a straight-ahead state is reduced when the control angle in the straight-ahead state deviates from the value indicating the straight-ahead state.

Description

Technical Field

[0001] This invention relates to a steering control device and a method for adjusting standard values. Background Technology

[0002] For example, the steering mechanism described in Japanese Unexamined Patent Application Publication No. 2020-142596 (JP 2020-142596 A) has been proposed as a steering mechanism installed in a vehicle. The steering mechanism described in JP 2020-142596 A is a so-called steer-by-wire type steering mechanism, in which the power transmission path between the vehicle's steering wheel and the vehicle's steering wheels is cut off. The steering mechanism described in JP 2020-142596 A includes a steering control unit and a steering unit. The steering control unit includes a steering control side actuator that operates to apply a steering control reaction force to the steering wheel. The steering unit includes a steering side actuator that operates to steer the steering wheels. Summary of the Invention

[0003] When controlling the operation of the steering unit, the steering control device described in JP 2020-142596 A, for example, uses the angle associated with steering as the control angle to perform feedback control so that the steering wheels turn to a target steering state. The angle associated with steering is angular information representing the steering state of the steering wheels and is specified as an absolute angle relative to a defined standard value. This standard value is a value associated with a neutral position, which is the mechanical state of the steering unit representing the forward straight-ahead state of the steering wheels. For example, the standard value is set during the work of assembling the steering unit in a factory or similar location. In some cases, the standard value is set during the work of assembling the steering unit to a value deviating from the neutral position representing the forward straight-ahead state of the steering wheels. In this case, even when the steering wheels are in the forward straight-ahead state, the angle associated with steering deviates from the value representing the forward straight-ahead state. This may lead to a reduction in the effectiveness of performing feedback control on the angle associated with steering. Such a problem not only occurs in steering control devices with steering by line but also in steering control devices that use angle information representing the steering state of the steering wheels as the control angle to perform feedback control.

[0004] A first aspect of the present invention is a steering control device. The steering control device controls a steering mechanism as a target, the steering mechanism including a steering unit that operates to steer the steering wheels of a vehicle. The steering control device includes a control unit that stores standard values ​​and controls the operation of the steering unit. The standard values ​​are values ​​associated with a mechanical state of the steering unit representing a forward straight-ahead state, which is the steering state of the steering wheels when the vehicle is moving forward straight. The control unit is configured to perform control angle calculation processing, angle feedback processing, and standard value adjustment processing. The control angle calculation processing is a process of calculating a control angle as an absolute angle relative to the standard value, wherein the control angle is angle information representing the actual steering state of the steering wheels; the angle feedback processing is a process of performing feedback control on the control angle to steer the steering wheels to the target steering state; and the standard value adjustment processing is a process of adjusting the stored standard values ​​in the event of a diagnostic state for diagnosing an abnormal state of the vehicle. The standard value adjustment processing includes the following process: when the control angle in the forward straight-ahead state deviates from the value representing the forward straight-ahead state, the standard value is adjusted so that the deviation between the control angle and the value representing the forward straight-ahead state is reduced.

[0005] According to this configuration, for example, when the standard value deviates from the value associated with the mechanical state of the steering unit, which represents the forward straight-line state of the steering wheels, due to reasons attributable to the work of assembling the steering unit, the standard value can be adjusted through a standard value adjustment process. This standard value adjustment process is performed when a diagnostic state occurs. A diagnostic state is, for example, a situation where it is not expected that a user of the vehicle will enter the vehicle and perform driving, and corresponds to a situation where the vehicle is undergoing maintenance. A situation where vehicle maintenance is underway is one where even if the feedback control of the control angle is affected by the adjustment of the standard value, it will not cause inconvenience to the user of the vehicle. Therefore, when the control angle deviates from the value representing the forward straight-line state of the steering wheels, this deviation of the control angle can be reduced without causing inconvenience to the user of the vehicle. Therefore, the reduction in the effectiveness of feedback control of the control angle can be effectively mitigated.

[0006] In the aforementioned steering control device, the standard value adjustment process may include the following process: adjusting the standard value to reflect the offset value obtained based on the control angle in the forward straight state.

[0007] Based on this configuration, the offset value can be obtained by simply creating a forward straight-line state for the steering wheels. This is effective in simplifying the standard value adjustment process.

[0008] In the aforementioned steering control device, the standard value adjustment process may include the following process: setting an upper limit for the absolute value of the offset value.

[0009] This configuration reduces the likelihood of large absolute values ​​of the offset, which can lead to significant differences in the steering range of the steering wheels between the left and right. Therefore, the standard value can be adjusted without causing discomfort to the vehicle's occupants during driving.

[0010] In the aforementioned steering control device, the control unit can be configured to perform a standard value adjustment process during vehicle operation when a diagnostic state occurs. The standard value adjustment process may include obtaining a value as an offset value by accumulating a unit quantity, where the unit quantity is smaller than the value representing the deviation of the control angle from the value indicating the forward straight-ahead state.

[0011] According to this configuration, for example, the standard value can be adjusted during driving while the vehicle is in motion, even when the maintenance worker is driving it. In this case, since the vehicle can actually be driven, the deviation between the control angle of the steering wheel in the forward straight-line state and the value representing the forward straight-line state can be accurately reflected in the adjustment of the standard value. Furthermore, since the value obtained by accumulating unit quantities can be used as the offset value, the adjustment of the standard value can be performed stepwise. This is effective in ensuring the safety of the maintenance worker when adjusting the standard value while the vehicle is in motion.

[0012] In the aforementioned steering control device, the control unit can be configured to perform standard value adjustment processing when the vehicle is stationary in the event of a diagnostic condition. The standard value adjustment processing may include obtaining the control angle as an offset value while traveling straight forward.

[0013] According to this configuration, for example, a maintenance worker can adjust the standard value when the vehicle is stationary. In this case, since the vehicle is stationary, the adjustment of the standard value can be performed without considering the impact of the adjustment on the feedback control of the control angle. This is effective in ensuring the safety of maintenance workers and achieving efficient work when adjusting the standard value.

[0014] A second aspect of the invention is a standard value adjustment method. The standard value adjustment method adjusts a standard value, which is information stored in a control unit belonging to a steering control device that controls a steering mechanism as a target. The steering mechanism includes a steering unit that operates to steer the vehicle's steering wheels. The standard value is a value associated with the mechanical state of the steering unit, representing a forward straight-ahead state, which is the steering state of the steering wheels when the vehicle is moving forward straight. The standard value adjustment method includes a diagnostic state setting step and a standard value adjustment step. In the diagnostic state setting step, the standard value is used when the control unit calculates a control angle as an absolute angle relative to the standard value, where the control angle is angle information representing the actual steering state of the steering wheels; the control angle is used as a control quantity when the control unit performs feedback control to steer the steering wheels to the target steering state while controlling the operation of the steering unit; and a diagnostic state for diagnosing abnormal conditions of the vehicle is set by operating a diagnostic tool connected externally to the vehicle. In the standard value adjustment step, the standard value stored in the control unit is adjusted when the diagnostic state is set. The standard value adjustment procedure includes the following steps: when the control angle in the forward straight-ahead state deviates from the value representing the forward straight-ahead state, the standard value is adjusted by operating the diagnostic tool so that the deviation between the control angle and the value representing the forward straight-ahead state is reduced.

[0015] According to this method, for example, when a standard value deviates from the value associated with the mechanical state of the steering unit, representing the forward straight-line state of the steering wheels, due to reasons attributable to the work of assembling the steering unit, the standard value can be adjusted through a standard value adjustment process. This standard value adjustment process is performed in the event of a diagnostic state. A diagnostic state is, for example, a situation where it is not expected that a user of the vehicle will enter the vehicle and perform driving, and corresponds to a situation where the vehicle is undergoing maintenance. A situation where vehicle maintenance is underway is one where even if the feedback control of the control angle is affected by the adjustment of the standard value, it will not cause inconvenience to the user of the vehicle. Therefore, when the control angle deviates from the value representing the forward straight-line state in the forward straight-line state of the steering wheels, this deviation of the control angle can be reduced without causing inconvenience to the user of the vehicle. Therefore, the reduction in the effectiveness of feedback control of the control angle can be effectively mitigated.

[0016] According to the present invention, the reduction in the effectiveness of feedback control on the control angle can be effectively mitigated. Attached Figure Description

[0017] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, in which similar reference numerals denote similar elements, and in the drawings:

[0018] Figure 1 This is a diagram illustrating a schematic configuration of a steer-by-wire steering system;

[0019] Figure 2 This is a block diagram illustrating the functions of the steering control device;

[0020] Figure 3 This is a flowchart illustrating the standard value adjustment process in the first embodiment;

[0021] Figure 4 This is a flowchart illustrating the standard value adjustment method in the first embodiment;

[0022] Figure 5 This is a view showing the state in which the standard value deviates from the rack neutral position, which represents the forward straight-ahead state of the steering wheel;

[0023] Figure 6 This is a view showing how the standard values ​​are adjusted in the first embodiment;

[0024] Figure 7 This is a flowchart illustrating the standard value adjustment process in the second embodiment;

[0025] Figure 8 This is a flowchart illustrating the standard value adjustment method in the second embodiment; and

[0026] Figure 9 This is a view showing how the standard values ​​are adjusted in the second embodiment. Detailed Implementation

[0027] First Implementation Method

[0028] The steering control device 1 according to the first embodiment will now be described. Figure 1 As shown, the steering control device 1 controls the steering device 2, which is the target. The steering device 2 is configured as a steer-by-wire vehicle steering device. The steering device 2 includes a steering control unit 4 and a steering unit 6. The steering control unit 4 is operated by the driver via the vehicle's steering wheel 3. The steering unit 6 turns the vehicle's left and right steering wheels 5 according to the driver's steering input to the steering control unit 4. The steering device 2 of this embodiment has a structure in which the power transmission path between the steering control unit 4 and the steering unit 6 is always mechanically cut off. Therefore, the steering device 2 has a structure in which the power transmission path between the steering control side actuator 12 (described later) and the steering side actuator 31 (described later) is always mechanically cut off.

[0029] The steering control unit 4 includes a steering control shaft 11 and a steering control side actuator 12. The steering control shaft 11 is connected to the steering wheel 3. The steering control side actuator 12 has a steering control side motor 13 as a drive source and a steering control side reduction mechanism 14. The steering control side motor 13 is a reaction force motor, which applies a steering control reaction force as a force resisting steering control to the steering wheel 3 via the steering control shaft 11. The steering control side motor 13 is connected to the steering control shaft 11 via, for example, the steering control side reduction mechanism 14 formed by a worm and a worm wheel. As the steering control side motor 13 in this embodiment, a three-phase brushless motor is used, for example.

[0030] The steering unit 6 includes a pinion shaft 21, a rack shaft 22 serving as a steering shaft, and a rack housing 23. The pinion shaft 21 and the rack shaft 22 are connected to each other at a predetermined intersection angle. The pinion teeth 21a formed on the pinion shaft 21 mesh with the rack teeth 22a formed on the rack shaft 22 to form a rack and pinion mechanism 24. Therefore, the pinion shaft 21, corresponding to its rotation angle, can be converted into a rotation axis that serves as the steering angle θi of the steering position of the steering wheel 5. The rack housing 23 houses the rack and pinion mechanism 24. One end of the pinion shaft 21 protrudes from the rack housing 23 on the side opposite to the side connected to the rack shaft 22. Both ends of the rack shaft 22 protrude from both ends of the rack housing 23 in the axial direction. A tie rod 26 is connected to the corresponding end of the rack shaft 22 via a rack end 25 formed by a ball joint. The front end of the tie rod 26 is connected to a steering knuckle (not shown) that is combined with the left steering wheel and the right steering wheel 5, respectively.

[0031] The steering unit 6 includes a steering-side actuator 31. The steering-side actuator 31 includes a steering-side motor 32 as a drive source, a transmission mechanism 33, and a conversion mechanism 34. The steering-side motor 32 applies a steering force to the rack shaft 22 to turn the steering wheel 5 via the transmission mechanism 33 and the conversion mechanism 34. The steering-side motor 32 transmits rotation to the conversion mechanism 34 via the transmission mechanism 33, which is, for example, a belt drive mechanism. The transmission mechanism 33 converts the rotation of the steering-side motor 32 into the reciprocating motion of the rack shaft 22 via the conversion mechanism 34, which is, for example, a ball screw mechanism. The steering-side motor 32 in this embodiment is, for example, a three-phase brushless motor.

[0032] In the steering control device 2 constructed in this way, the steering angle θi of the steering wheel 5 changes as the motor torque is applied as a steering force from the steering-side actuator 31 to the rack shaft 22 according to the driver's steering operation. In this case, a steering reaction force resisting the driver's steering operation is applied from the steering-side actuator 12 to the steering wheel 3. Therefore, in the steering control device 2, the steering torque Th required to turn the steering wheel 3 is changed by the steering reaction force, which is the motor torque applied from the steering-side actuator 12.

[0033] The reason for providing the pinion shaft 21 is to support the rack shaft 22 together with the pinion shaft 21 within the rack housing 23. That is, the rack shaft 22 is supported by a support mechanism (not shown) provided in the steering control device 2, allowing it to move axially and be pressed against the pinion shaft 21. Therefore, the rack shaft 22 is supported within the rack housing 23. However, another support mechanism can be provided to support the rack shaft 22 within the rack housing 23 without using the pinion shaft 21.

[0034] Electrical configuration of steering control device 2

[0035] like Figure 1 As shown, the steering control side motor 13 and the steering side motor 32 are connected to the steering control device 1. The steering control device 1 controls the operation of the steering control side motor 13 and the steering side motor 32.

[0036] The detection results from various sensors are input into the steering control unit 1. Various sensors are connected to the steering control unit 1. These sensors include, for example, a torque sensor 41, a steering side rotation angle sensor 42, a steering side rotation angle sensor 43, and a vehicle speed sensor 44.

[0037] Torque sensor 41 detects steering torque Th, which represents the torque applied to steering shaft 11 by the driver's steering operation. Steering-side rotation angle sensor 42 detects rotation angle θa, which is the angle of the rotation shaft of steering-side motor 13, within a 360-degree range. Steering-side rotation angle sensor 43 detects rotation angle θb, which is the angle of the rotation shaft of steering-side motor 32, within a 360-degree range. Vehicle speed sensor 44 detects vehicle speed V, which is the vehicle's travel speed.

[0038] Specifically, the torque sensor 41 is positioned on the steering wheel 3 side of the steering shaft 11 relative to the steering control side deceleration mechanism 14. The torque sensor 41 detects the steering torque Th based on the torsion of the torsion bar 41a located in the middle portion of the steering shaft 11. For example, the steering torque Th is detected as positive when the vehicle is turning right and as negative when the vehicle is turning left.

[0039] A steering-side rotation angle sensor 42 is installed in the steering-side motor 13. The rotation angle θa of the steering-side motor 13 is used to calculate the steering angle θh. The steering-side motor 13 and the steering shaft 11 operate in conjunction with each other via a steering-side reduction mechanism 14. Therefore, there is a correlation between the rotation angle θa of the steering-side motor 13 and the rotation angle of the steering shaft 11, and thus a correlation with the steering angle θh, which represents the rotational position of the steering wheel 3. Therefore, the steering angle θh can be obtained based on the rotation angle θa of the steering-side motor 13. The steering angle θa is detected as a positive value, for example, when the vehicle is turning right, and as a negative value when the vehicle is turning left.

[0040] A steering-side rotation angle sensor 43 is installed in the steering-side motor 32. The rotation angle θb of the steering-side motor 32 is used to calculate the pinion angle θp. The steering-side motor 32 and the pinion shaft 21 operate in conjunction with each other via a transmission mechanism 33, a conversion mechanism 34, and a rack and pinion mechanism 24. Therefore, there is a correlation between the rotation angle θb of the steering-side motor 32 and the pinion angle θp, which is the rotation angle of the pinion shaft 21. Therefore, the pinion angle θp can be obtained based on the rotation angle θb of the steering-side motor 32. The pinion shaft 21 meshes with the rack shaft 22. Therefore, there is also a correlation between the pinion angle θp and the amount of movement of the rack shaft 22. Therefore, the pinion angle θp is angular information representing the steering state of the steering wheel 5, and is a value reflecting the steering angle θi, which is the steering position of the steering wheel 5. The rotation angle θb is detected as a positive value, for example, when the vehicle is turning right, and as a negative value when the vehicle is turning left.

[0041] Diagnostic tool 45 can be connected to steering control unit 1. Diagnostic tool 45 is used, for example, in a vehicle repair shop such as a dealership. Diagnostic tool 45 is connected to the vehicle from the outside. The steering control unit 1 of this embodiment has a connector 45a. Diagnostic tool 45 is connected to the vehicle from the outside via connector 45a of steering control unit 1. Connector 45a may be part of a control device separately installed in the vehicle from steering control unit 1, or it may be installed in the vehicle as a dedicated connector. Diagnostic tool 45 is a tool used to diagnose abnormal conditions of the vehicle.

[0042] When connected to the steering control unit 1, the diagnostic tool 45 commands the vehicle, i.e., the steering control unit 1, to be set to factory mode for diagnostic purposes via an operation command from the mechanic. Factory mode is set when it is not desired that the vehicle user will enter the vehicle and perform driving actions, and when the vehicle is undergoing maintenance. In factory mode, the mechanic can use the diagnostic tool 45 to check the results of diagnosing any abnormal conditions in the vehicle, i.e., the steering control unit 1. The mechanic can then take appropriate action based on the diagnostic results through the operation of the diagnostic tool 45.

[0043] Functions of steering control device 1

[0044] The steering control unit 1 includes a central processing unit (CPU) and a memory (neither shown). The steering control unit 1 performs various processes when the CPU executes a program stored in the memory at predetermined computation cycles. The CPU and memory constitute a microcomputer as processing circuitry. The memory includes computer-readable media, such as random access memory (RAM) or read-only memory (ROM). However, this is one example of various processes implemented in software. The processing circuitry belonging to the steering control unit 1 can be configured to implement at least some of the processes via hardware circuitry, such as logic circuitry.

[0045] Figure 2 Some processes performed by the steering control unit 1 are shown. Figure 2 The processes shown are some of the processes that are implemented when the CPU executes a program stored in memory, as described by the type of process to be implemented.

[0046] The steering control device 1 includes a steering control side control unit 50 and a steering side control unit 60. The steering control side control unit 50 controls the power supply to the steering control side motor 13. The steering control side control unit 50 includes a steering control side current sensor 54. The steering control side current sensor 54 detects the actual steering control side current value Ia, which is obtained based on the current value of each phase of the steering control side motor 13 flowing through the connection line between the steering control side control unit 50 and the motor coils of each phase of the steering control side motor 13. The steering control side current sensor 54 obtains the voltage drop as current from the shunt resistor connected to the source side of each switching element in an inverter (not shown), which is configured to correspond to the steering control side motor 13. Figure 2 In this diagram, for ease of description, the connection lines of each phase and the current sensors of each sensor are collectively shown as a single connection line and a single current sensor.

[0047] The steering-side control unit 60 controls the power supply to the steering-side motor 32. The steering-side control unit 60 has a steering-side current sensor 65. The steering-side current sensor 65 detects the actual steering-side current value Ib, which is obtained from the current value of each phase of the steering-side motor 32 flowing through the connection line between the steering-side control unit 60 and the motor coils of each phase of the steering-side motor 32. The steering-side current sensor 65 obtains the voltage drop as current from the shunt resistor connected to the source side of each switching element in an inverter (not shown), which is configured to correspond to the steering-side motor 32. Figure 2 In this embodiment, for ease of description, the connection lines of each phase and the current sensors of each phase are collectively shown as one connection line and one current sensor. In this embodiment, the steering-side control unit 60 is an example of a control unit that controls the operation of the steering unit 6 (i.e., the steering-side actuator 31) of the steering control device 2.

[0048] Steering control side control unit 50

[0049] like Figure 2 As shown, the steering torque Th, vehicle speed V, rotation angle θa, actual steering side current value Ib, and steering conversion angle θp_s (described later) are input to the steering control side control unit 50. The steering control side control unit 50 controls the power supply to the steering control side motor 13 based on the steering torque Th, vehicle speed V, rotation angle θa, actual steering side current value Ib, and steering conversion angle θp_s. The steering conversion angle θp_s is calculated based on the pinion angle θp.

[0050] The steering control unit 50 includes a steering angle calculation unit 51, a target reaction torque calculation unit 52, and a current application control unit 53. The rotation angle θa is input to the steering angle calculation unit 51. The steering angle calculation unit 51 converts the rotation angle θa into an integrated angle encompassing a range exceeding 360°, for example, by counting the revolutions of the steering-side motor 13 from the steering neutral position (which is the position of the steering wheel 3 when the vehicle is moving straight forward). The steering angle calculation unit 51 calculates the steering angle θh by multiplying the integrated angle obtained through the conversion by a conversion factor based on the speed ratio of the steering-side reduction gear 14. That is, the steering angle calculation unit 51 calculates the steering angle θh as an absolute angle relative to the steering neutral position. The resulting steering angle θh is output to the target reaction torque calculation unit 52 and the steering control unit 60.

[0051] The steering torque Th, vehicle speed V, actual steering side current value Ib, steering conversion angle θp_s (described later), and steering angle θh are input into the target reaction torque calculation unit 52. The target reaction torque calculation unit 52 calculates the target reaction torque command value Ts* based on the steering torque Th, vehicle speed V, actual steering side current value Ib, steering conversion angle θp_s, and steering angle θh. The target reaction torque command value Ts* is the target reaction force control quantity of the steering reaction force of the steering wheel 3 generated by the steering side motor 13. The obtained target reaction torque command value Ts* is output to the current application control unit 53.

[0052] The target reaction torque command value Ts*, the rotation angle θa, and the actual steering side current value Ia are input to the current application control unit 53. The current application control unit 53 calculates the current command value Ia* for the steering side motor 13 based on the target reaction torque command value Ts*. Then, the current application control unit 53 obtains the deviation between the current value in the dq coordinate system (obtained by converting the actual steering side current value Ia detected by the steering side current sensor 54 based on the rotation angle θa) and the current command value Ia*, and controls the power supply to the steering side motor 13 to eliminate this deviation. As a result, the steering side motor 13 generates torque according to the target reaction torque command value Ts*. Therefore, the driver can feel an appropriate steering response corresponding to the road reaction force.

[0053] Steering side control unit 60

[0054] like Figure 2 As shown, the vehicle speed V, rotation angle θb, and steering angle θh are input to the steering-side control unit 60. The steering-side control unit 60 controls the power supply to the steering-side motor 32 based on the vehicle speed V, rotation angle θb, and steering angle θh.

[0055] The steering side control unit 60 includes a pinion angle calculation unit 61, a steering angle ratio variable control unit 62, and an angle feedback control unit. Figure 2 The “pinion angle feedback control unit” 63 and the current application control unit 64 are included.

[0056] The rotation angle θb is input to the pinion angle calculation unit 61. The pinion angle calculation unit 61 converts the rotation angle θb into an integrated angle encompassing a range exceeding 360° by counting the revolutions of the steering-side motor 32 from the rack neutral position (which is the position of the rack shaft 22 when the vehicle is moving forward straight). The pinion angle calculation unit 61 calculates the pinion angle θp, which is the actual rotation angle of the pinion shaft 21, by multiplying the integrated angle obtained through conversion by a conversion factor based on the speed ratio of the transmission mechanism 33, the lead of the conversion mechanism 34, and the speed ratio of the rack and pinion mechanism 24. Therefore, the pinion angle calculation unit 61 calculates the pinion angle θp as an absolute angle relative to the rack neutral position. The thus obtained pinion angle θp is output to the steering angle ratio variable control unit 62 and the angle feedback control unit 63.

[0057] Vehicle speed V, steering angle θh, and pinion angle θp are input to the variable steering angle ratio control unit 62. The variable steering angle ratio control unit 62 calculates a target pinion angle θp* based on the steering angle θh. The target pinion angle θp* is a target control quantity for the pinion angle θp (i.e., the steering state of the steering wheel 5) obtained as a result of steering the steering wheel 5. Taking into account the steering angle ratio, which is the ratio between the steering angle θh and the pinion angle θp, the target pinion angle θp* is calculated relative to the steering angle θh as an angle scaled to the pinion angle θp. The variable steering angle ratio control unit 62 calculates the steering conversion angle θp_s based on the pinion angle θp. Taking into account the steering angle ratio, the steering conversion angle θp_s is calculated relative to the pinion angle θp as an angle scaled to the steering angle θh.

[0058] The variable steering angle ratio control unit 62 changes the steering angle ratio according to the vehicle speed V. For example, the variable steering angle ratio control unit 62 changes the steering angle ratio to change the pinion angle θp more significantly with respect to the change in steering angle θh when the vehicle speed V is low, compared to when the vehicle speed V is high. That is, in the calculation of the target pinion angle θp*, a conversion calculation is performed so that the positional relationship between the target pinion angle θp* and the steering angle θh satisfies a predetermined correspondence. In the calculation of the steering conversion angle θp_s, for example, a reverse conversion calculation using the reciprocal of the value used in the conversion calculation mentioned above is performed so that the positional relationship between the steering conversion angle θp_s and the pinion angle θp satisfies a predetermined correspondence. The target pinion angle θp* obtained thereby is output to the angle feedback control unit 63. The steering conversion angle θp_s is output to the steering control side control unit 50, i.e., the target reaction torque calculation unit 52.

[0059] The target pinion angle θp* and the pinion angle θp are input to the angle feedback control unit 63. The angle feedback control unit 63 calculates the steering force command value Tp* as the target control quantity for steering force by performing feedback control on the pinion angle θp to adapt the pinion angle θp to the target pinion angle θp*. The resulting steering force command value Tp* is output to the current application control unit 64. In this embodiment, the pinion angle θp is an example of a control angle.

[0060] The steering force command value Tp*, the rotation angle θb, and the actual steering side current value Ib are input to the current application control unit 64. The current application control unit 64 calculates the current command value Ib* for the steering side motor 32 based on the steering force command value Tp*. Then, the current application control unit 64 obtains the deviation between the current value in the dq coordinate system obtained by converting the actual steering side current value Ib detected by the steering side current sensor 65 based on the rotation angle θb and the current command value Ib*, and controls the power supply to the steering side motor 32 to eliminate this deviation. As a result, the steering side motor 32 rotates by an angle corresponding to the steering force command value Tp*. Therefore, the steering side control unit 60 controls the operation of the steering control device 2, i.e., the steering unit 6, such that the positional relationship between the steering control angle θh and the pinion angle θp, i.e., between the steering control angle θh and the steering angle θi, satisfies a predetermined correspondence defined according to the steering control angle ratio.

[0061] Regarding the standard value θsd

[0062] like Figure 2 As shown, the steering control unit 60 has a storage unit 66. Storage unit 66 is a predetermined storage area in the memory of the steering control device 1. Storage unit 66 stores a standard value θsd, which is a value associated with the mechanical state of the steering unit 6 representing a forward straight-ahead state, the steering state of the steering wheel 5 when the vehicle is moving forward straight. That is, the standard value θsd represents the rack's neutral position. Therefore, the pinion angle calculation unit 61 performs a control angle calculation process, calculating the pinion angle θp as an absolute angle relative to the standard value θsd.

[0063] For example, a standard value θsd is set during the assembly of the steering unit 6 at a factory or similar location. During this assembly, the standard value θsd is set to the value representing the zero value of the pinion angle θp when the steering wheel 5 is in a forward straight-line state and the rack shaft 22 is in the rack neutral position. The zero value of the pinion angle θp corresponds to the zero value of the steering angle θh, which represents the position of the steering wheel 3, corresponding to the neutral position of the steering operation. In some cases, the standard value θsd is set to a value deviating from the rack neutral position due to reasons attributable to the assembly of the steering unit 6. In this case, the zero value of the pinion angle θp is not the value corresponding to the zero value of the steering angle θh, which represents the position of the steering wheel 3, corresponding to the neutral position of the steering operation. This leads to a situation where, when the steering-side control unit 60 performs feedback control on the pinion angle θp to satisfy the angle corresponding to the steering angle θh, a deviation occurs in the relationship between the position of the steering wheel 3 and the steering state of the steering wheel 5. To address this situation, the steering-side control unit 60 adjusts the standard value θsd stored in the storage unit 66. The standard value adjustment process for adjusting the standard value θsd will be described in detail below.

[0064] Standard value adjustment processing

[0065] like Figure 3 As shown, the steering-side control unit 60 performs a standard value adjustment process at a predetermined control cycle. In the standard value adjustment process, the steering-side control unit 60 determines whether a factory mode has appeared (step S10). In step S10, the steering-side control unit 60 determines whether a mode setting command for setting the factory mode has been input via the diagnostic tool 45. When the steering-side control unit 60 determines that no mode setting command has been input and therefore no factory mode has appeared (step S10: No), the steering-side control unit 60 ends the standard value adjustment process and moves to another process.

[0066] On the other hand, when the steering side control unit 60 determines in step S10 that a mode setting command has been input and thus a factory mode has appeared (step S10: Yes), the steering side control unit 60 determines whether the system including the steering control device 2, which includes the steering control device 1, is functioning correctly (step S11). In step S11, the steering side control unit 60 determines whether normal steering side control can be properly performed for the steer-by-wire steering control device 2. Normal steering side control means reflecting the state of the steering control unit 4 in the state of the steering unit 6, thereby controlling the steering wheel 5 to rotate at an angle corresponding to the steering operation performed by the driver. When the steering side control unit 60 determines that normal steering side control cannot be properly performed (step S11: No), the steering side control unit 60 ends the standard value adjustment process and moves to another process. When the steering side control unit 60 determines that normal steering side control cannot be properly performed, the steering side control unit 60 outputs information about this result to the diagnostic tool 45.

[0067] On the other hand, when the steering side control unit 60 determines in step S11 that normal steering side control can be properly performed (step S11: Yes), the steering side control unit 60 determines whether an offset command has been input through the diagnostic tool 45 (step S12). When no offset command has been input (step S12: No), the steering side control unit 60 ends the standard value adjustment process and moves to another process.

[0068] On the other hand, when an offset command is input in step S12 (step S12: Yes), the steering-side control unit 60 updates the offset value θofs (step S13). In step S13, the steering-side control unit 60 updates the offset value θofs to reflect the leftward adjustment amount θl or rightward adjustment amount θr commanded by the offset command. The offset value θofs is the value used to adjust the standard value θsd. The steering-side control unit 60 uses the value obtained by adding the offset value θofs to the standard value θsd stored in the storage unit 66 or subtracting the offset value θofs from the standard value θsd as the adjusted standard value θsd used to calculate the pinion angle θp. For the offset value θofs, zero is set as the initial value. Therefore, when the offset value θofs is zero, the adjusted standard value θsd is the same value as the standard value θsd stored in the storage unit 66 that was set during the work of assembling the steering unit 6 at the factory, etc.

[0069] In step S13, the steering control unit 60 increases or decreases the offset value θofs by a predetermined unit amount according to the offset command determined in step S12. For example, when the offset command commands a leftward adjustment θl, the steering control unit 60 increases the offset value θofs by a unit amount. This means adjusting the standard value θsd to shift to the rightward steering control side, which is the positive direction of the rotation angle θb. On the other hand, when the offset command commands a rightward adjustment θr, the steering control unit 60 decreases the offset value θofs by a unit amount. This means adjusting the standard value θsd to shift to the leftward steering control side, which is the negative direction of the rotation angle θb. The unit amount is, for example, set to a value within an experimentally obtained range that is small compared to an imaginable deviation from the standard value θsd.

[0070] Then, the steering-side control unit 60 determines whether the absolute value of the offset value θofs, which has been updated in step S13, is equal to or less than the threshold θth (step S14). In step S14, the steering-side control unit 60 limits the upper limit of the absolute value of the offset value θofs so that the absolute value does not become too large. The threshold θth is, for example, a value set within an experimentally obtained range that ensures the difference in the steering range of the steering wheel 5 or the steering operation range between the left and right sides does not cause discomfort to the driver.

[0071] In step S14, when the absolute value of the offset value θofs, which has been updated in step S13, is equal to or less than the threshold θth (step S14: Yes), the steering side control unit 60 ends the standard value adjustment process and moves to other processes. In this case, the steering side control unit 60 uses the offset value θofs, which has been updated in step S13, to adjust the subsequent standard value θsd.

[0072] On the other hand, when the absolute value of the offset value θofs updated in step S13 is greater than the threshold θth (step S14: No), the steering control unit 60 limits the absolute value of the offset value θofs to the threshold θth (step S15). Upon reaching step S15, the steering control unit 60 uses the offset value θofs obtained by limiting the absolute value of the value updated in step S13 to the threshold θth for subsequent adjustments to the standard value θsd. Afterwards, the steering control unit 60 ends the standard value adjustment process and moves to other processes.

[0073] As a result of the standard value adjustment process, which involves repeatedly executing steps S10 to S15 at predetermined control cycles, each time an offset command is determined to have been input in step S12, the steering side control unit 60 cumulatively reflects the leftward adjustment amount θl or the rightward adjustment amount θr. Therefore, the steering side control unit 60 is configured to obtain an offset value θofs as the value obtained by accumulating a unit amount based on the leftward adjustment amount θ1 or the rightward adjustment amount θr. Furthermore, the steering side control unit 60 is configured to limit the offset value θofs to a range that does not cause discomfort to the driver, rather than accumulating the offset value θofs indefinitely.

[0074] Standard value adjustment method

[0075] like Figure 4 As shown, a worker at a vehicle repair shop (e.g., a dealership) adjusts the standard value θsd according to the following standard value adjustment method. In this standard value adjustment method, the worker connects a diagnostic tool 45 to the vehicle, i.e., the steering control unit 1 (step S100). Then, the worker sets the factory mode by operating the diagnostic tool 45 (step S101). In this case, the diagnostic tool 45 outputs a mode setting command to instruct the steering control unit 1 to set the factory mode. In this embodiment, steps S100 and S101 correspond to the diagnostic state setting steps.

[0076] Then, the worker drives the vehicle in factory mode (step S102). In step S102, the worker drives the vehicle so that the steering wheel 5 is in a forward-straight-forward state. For example, when the standard value θsd is a value deviating from the rack neutral position, positioning the steering wheel 3 to make the vehicle move forward straight causes the position of the steering wheel 3 to shift from the steering wheel neutral position toward either the left-hand steering or right-hand steering side. The amount of shift when the position shifts toward one steering side corresponds to the magnitude of the deviation of the standard value θsd from the rack neutral position.

[0077] Then, the operator outputs an offset command through the operation of the diagnostic tool 45 (step S103). In step S103, the operator operates the diagnostic tool 45 to output an offset command of either a leftward adjustment amount θl or a rightward adjustment amount θr, depending on the position of the steering wheel 3. For example, when the position of the steering wheel 3 has shifted from the neutral position toward the right steering control side, the operator executes the operation of outputting an offset command of a leftward adjustment amount θ1. This means adjusting the standard value θsd to shift toward the right steering control side in the positive direction of the rotation angle θb. On the other hand, when the position of the steering wheel 3 has shifted from the neutral position toward the left steering control side, the operator executes the operation of outputting an offset command of a rightward adjustment amount θr. This means adjusting the standard value θsd to shift toward the left steering control side in the negative direction of the rotation angle θb.

[0078] When an offset command is input, the steering-side control unit 60 adjusts the standard value θsd by updating the offset value θofs. The steering-side control unit 60 performs feedback control on the pinion angle θp obtained using the adjusted standard value θsd to satisfy the angle corresponding to the steering angle θh. The steering-side control unit 60 controls the steering mechanism 2 such that the positional relationship between the steering angle θh and the pinion angle θp, i.e., between the steering angle θh and the steering angle θi, approximates a predetermined correspondence defined according to the steering angle ratio. As a result, the operator notices that when the vehicle is driven so that the steering wheel 5 is in a forward straight-ahead state, the amount of displacement of the steering wheel 3 from its neutral position toward the right steering side decreases.

[0079] When checking the position of the steering wheel 3, the worker repeatedly outputs the offset command, bringing the position close to the neutral position of the steering wheel (step S103). When the repeated output of the offset command causes the steering-side control unit 60 to determine that the absolute value of the offset value θofs is greater than the threshold θth (step S14: No), the position of the steering wheel 3 stops changing. Steps S102 and S103 in this embodiment correspond to the standard value adjustment step.

[0080] Then, when the worker determines that the adjustment of the standard value θsd has been completed while checking the position of the steering wheel 3, the worker ends the factory mode by operating the diagnostic tool 45 (step S104). Then, the worker removes the diagnostic tool 45 from the steering control unit 1 (step S105) and ends the work of adjusting the standard value.

[0081] How to adjust the standard value θsd

[0082] As an example, the following situation will be described: where, such as Figure 5 As shown, due to reasons attributable to the assembly of steering unit 6, the standard value θsd deviates by a deviation D from the rack neutral position toward the right steering control side. In this example, when the vehicle is driven such that steering wheel 5 is in a forward straight-ahead state, the value of pinion angle θp is used as the representation of steering wheel 5 in... Figure 5 The deviation D is calculated based on the directional deviation in the direction of the dashed arrow. Therefore, the position of steering wheel 3 deviates from the neutral position towards the right steering control side by an amount corresponding to the deviation D. This can be achieved through the operation performed by the worker. Figure 4 The standard value adjustment method shown and through Figure 3 The standard value θsd is adjusted by the standard value adjustment process performed by the steering side control unit 60. In this case, in the standard value adjustment method, the operator repeatedly outputs a command to adjust the leftward by an offset of θl through the operation of the diagnostic tool 45.

[0083] like Figure 6 As shown, in the standard value adjustment process, each time a command to adjust to the left by an offset amount θl is input, the steering side control unit 60 cumulatively increases the offset value θofs by a unit amount Dua. For example, as the left adjustment amount θl is commanded n times, the offset value θofs matches the deviation amount D. When the offset value θofs corresponding to the deviation amount D is added, the adjusted standard value θsd is adjusted to shift towards the right steering control side by the deviation amount D. Therefore, the adjusted standard value θsd matches the deviation amount D, that is, matches the rack neutral position, which is the value of the pinion angle θp when the vehicle is driven so that the steering wheel 5 is in a forward straight state.

[0084] In this way, when the vehicle is driven so that the steering wheel 5 is in a forward straight-line state, the value of the pinion angle θp is used as an indicator of the position of the steering wheel 5. Figure 5 The zero value is calculated based on the direction of the solid arrow in the center. Therefore, the position of steering wheel 3 matches the neutral position of the steering wheel.

[0085] Work of the implementation method

[0086] According to this embodiment, when the standard value θsd deviates from the rack neutral position due to reasons attributable to the operation of the steering unit 6, the steering side control unit 60 can adjust the standard value θsd through a standard value adjustment process. This standard value adjustment process is performed when the factory mode is active. The factory mode is set when it is not expected that the vehicle user will enter the vehicle and perform driving, etc., and corresponds to the situation where the vehicle is undergoing maintenance. When the vehicle is undergoing maintenance, it is such that even if the feedback control of the pinion angle θp is affected by the adjustment of the standard value θsd, it will not cause inconvenience to the vehicle user. Therefore, when the pinion angle θp deviates from zero in the forward straight-line state of the steering wheel 5, this deviation of the pinion angle θp can be reduced without causing inconvenience to the vehicle user.

[0087] Advantages of the implementation method

[0088] In this embodiment, when the pinion angle θp deviates from zero in the forward straight-moving state of the steering wheel 5, this deviation of the pinion angle θp can be reduced without causing inconvenience to the vehicle user. Therefore, the reduction in the effectiveness of feedback control of the pinion angle θp can be effectively mitigated.

[0089] In this implementation, the offset value θofs can be obtained by simply creating a forward straight-line state for the steering wheel 5. This is effective in simplifying the standard value adjustment process. In this implementation, the occurrence of situations where the absolute value of the offset value θofs becomes large, thus causing a significant difference in the steering range of the steering wheel 5 between the left and right sides, can be reduced. Therefore, the standard value θsd can be adjusted without causing discomfort to the vehicle user while driving.

[0090] In this embodiment, the worker can adjust the standard value θsd while the vehicle is moving. In this case, since the vehicle can actually be moved, the deviation between the pinion angle θp and the zero value of the steering wheel 5 in its forward straight-line state can be accurately reflected in the adjustment of the standard value θsd. Furthermore, since the value obtained by accumulating unit quantities can be used as the offset value θofs, the adjustment of the standard value θsd can be performed stepwise. This is effective in ensuring the safety of maintenance workers when adjusting the standard value θsd while the vehicle is moving.

[0091] Second Implementation Method

[0092] Next, the steering control device 1 according to the second embodiment will be described. For ease of description, the same components as in the first embodiment will be indicated by the same reference numerals as in the first embodiment, and their descriptions will be omitted.

[0093] Standard value adjustment processing

[0094] like Figure 7 As shown, in the standard value adjustment process, the steering side control unit 60 determines whether the factory mode has occurred (step S20). In step S20, the steering side control unit 60, in conjunction with... Figure 3 The determination is performed in the same manner as in step S10. If the steering side control unit 60 determines that no mode setting command has been input and therefore no factory mode has appeared (step S20: No), the steering side control unit 60 ends the standard value adjustment process and moves to another process.

[0095] On the other hand, if the steering side control unit 60 determines in step S20 that a mode setting command has been input and therefore factory mode has appeared (step S20: Yes), the steering side control unit 60 determines whether the system including the steering control device 2, which includes the steering control device 1, is functioning correctly (step S21). In step S21, the steering side control unit 60, in conjunction with... Figure 3 The determination is performed in the same manner as in step S11. When the steering side control unit 60 determines that normal steering side control cannot be properly performed (step S21: No), the steering side control unit 60 ends the standard value adjustment process and moves to another process.

[0096] On the other hand, when the steering side control unit 60 determines in step S21 that normal steering side control can be appropriately performed (step S21: Yes), the steering side control unit 60 determines whether the vehicle is stationary (step S22). In step S22, the steering side control unit 60 determines whether the vehicle speed V is lower than the vehicle speed threshold Vth. The vehicle speed threshold Vth is set such that the vehicle speed V is a value within an experimentally obtained range that includes the speed of a stationary vehicle when it is lower than the vehicle speed threshold Vth. When the steering side control unit 60 determines that the vehicle speed V is equal to or higher than the vehicle speed threshold Vth and therefore the vehicle is not stationary (step S22: No), the steering side control unit 60 ends the standard value adjustment process and moves to another process.

[0097] On the other hand, when the steering side control unit 60 determines that the vehicle speed V is lower than the vehicle speed threshold Vth and therefore the vehicle is stationary (step S22: Yes), the steering side control unit 60 determines whether an offset command has been input through the diagnostic tool 45 (step S23). When no offset command has been input (step S23: No), the steering side control unit 60 ends the standard value adjustment process and moves to another process.

[0098] On the other hand, when an offset command is input in step S23 (step S23: Yes), the steering side control unit 60 sets the offset value θofs (step S24). In step S24, triggered by the input of the offset command, the steering side control unit 60 sets the current pinion angle θp to the offset value θofs. In this embodiment, the offset command is information used to instruct the steering side control unit 60 to adjust the standard value θsd so that the current pinion angle θp satisfies the standard value θsd.

[0099] In this embodiment, the offset command is input while the steering state of the steering wheel 5 has been adjusted to the forward straight-ahead state in the steering unit 6. Therefore, when the steering-side control unit 60 determines whether an offset command has been input, the steering wheel 5 is in the forward straight-ahead state. In this case, if the pinion angle θp deviates from zero, the standard value θsd deviates from the rack neutral position by an amount corresponding to that deviation. In step S24, the steering-side control unit 60 setting the offset value θofs means adjusting the standard value θsd to satisfy the value of the pinion angle θp at this time.

[0100] Then, the steering-side control unit 60 determines whether the absolute value of the offset value θofs set in step S24 is equal to or less than the threshold θth (step S25). In step S25, the steering-side control unit 60... Figure 3The determination is performed in the same manner as in step S14. When the absolute value of the offset value θofs set in step S24 is equal to or less than the threshold θth (step S25: Yes), the steering side control unit 60 ends the standard value adjustment process and moves to other processes. In this case, the steering side control unit 60 uses the offset value θofs set in step S24 to adjust the subsequent standard value θsd.

[0101] On the other hand, when the absolute value of the offset value θofs set in step S24 is greater than the threshold θth (step S25: No), the steering control unit 60 limits the absolute value of the offset value θofs to the threshold θth (step S26). After step S26, the steering control unit 60 uses the offset value θofs obtained by limiting the absolute value of the value set in step S24 to the threshold θth for subsequent adjustments to the standard value θsd. Afterwards, the steering control unit 60 ends the standard value adjustment process and moves to other processes.

[0102] Standard value adjustment method

[0103] like Figure 8 As shown, in the standard value adjustment method, the worker connects the diagnostic tool 45 to the vehicle, i.e., the steering control device 1 (step S110), and sets the factory mode through the operation of the diagnostic tool 45 (step S111). Steps S110 and S111 are related to... Figure 4 Steps S100 and S101 are the same. Therefore, steps S110 and S111 correspond to the diagnostic state setting steps.

[0104] Then, with the factory mode set, the worker creates a forward-straight-ahead state for the steering wheel 5 when the vehicle is stationary (step S112). In step S112, the worker adjusts the steering state of the steering unit 6 so that the steering wheel 5 is in a forward-straight-ahead state. For example, when the standard value θsd is a value deviating from the rack neutral position, the position of the steering wheel 3 shifts from the steering wheel neutral position toward one of the left-hand steering or right-hand steering sides, as in the first embodiment.

[0105] Then, the operator outputs an offset command through the diagnostic tool 45 (step S113). The operator's operation in step S113 means adjusting the standard value θsd so that the position of the steering wheel 3 matches the neutral position of the steering wheel. In this embodiment, steps S112 and S113 correspond to the standard value adjustment step.

[0106] Then, when the worker checks the position of the steering wheel 3 and confirms that the standard value θsd adjustment has been completed, the worker ends the factory mode by operating the diagnostic tool 45 (step S114). Then, the worker removes the diagnostic tool 45 from the steering control unit 1 (step S115) and ends the adjustment of the standard value. Steps S114 and S115 are related to... Figure 4 The steps S104 and S105 are the same.

[0107] How to adjust the standard value θsd

[0108] exist Figure 5 In one example shown, it can be done by Figure 8 The standard value adjustment method performed by the worker is shown, and through Figure 9 The standard value θsd is adjusted by the standard value adjustment process performed by the steering side control unit 60. In this case, in the standard value adjustment method, the operator outputs an offset command through the operation of the diagnostic tool 45.

[0109] like Figure 9 As shown, when an offset command is input in the standard value adjustment process, the steering side control unit 60 sets the offset value θofs to the deviation amount D. Therefore, the offset value θofs matches the deviation amount D. Since the offset value θofs corresponding to the deviation amount D is added to the standard value θsd, the adjusted standard value θsd is adjusted to be shifted towards the right steering control side by the deviation amount D. Therefore, the adjusted standard value θsd matches the deviation amount D, which matches the rack neutral position, and the deviation amount D is the value of the pinion angle θp when the steering wheel 5 is in a forward straight-ahead state when the vehicle is stationary.

[0110] In this way, when creating a forward straight-line state for steering wheel 5 while the vehicle is stationary, the value of the pinion angle θp is calculated using the adjusted standard value θsd as zero. This zero value indicates that steering wheel 5 is in a forward straight-line state. Figure 5 The solid arrow in the diagram points in the direction of the direction. Therefore, the position of steering wheel 3 matches the neutral position of the steering wheel.

[0111] Advantages of the implementation method

[0112] In this implementation, the worker can adjust the standard value θsd when the vehicle is stationary. In this case, since the vehicle is stationary, the adjustment of the standard value θsd can be performed without considering the impact of the adjustment on the feedback control of the pinion angle θp. This is effective in ensuring the safety of maintenance workers and achieving efficient work when adjusting the standard value θsd.

[0113] Other implementation methods

[0114] Each of the above embodiments can be modified as follows. The following other embodiments can be combined with each other within a range that does not result in technical inconsistencies.

[0115] In the first embodiment, steps S14 and S15 of the standard value adjustment process can be omitted. The same applies to steps S25 and S26 of the standard value adjustment process in the second embodiment.

[0116] In the first embodiment, the threshold θth used in step S14 of the standard value adjustment process can be appropriately changed, as long as it is set from the viewpoint of reducing discomfort to the driver. For example, the threshold θth should be set to a value obtained experimentally that ensures the steering reaction force applied based on the steering angle θp_s or the vehicle's behavior does not cause discomfort to the driver. This also applies to the second embodiment.

[0117] In the first embodiment, the offset value θofs can be calculated instead of when the steering wheel 5 is in the forward straight-line state, after the steering wheel 5 has turned to its left or right limit. For example, in Figure 5 In one example shown, when the steering wheel 5 is turned to its left or right limit, the value of the pinion angle θp shifts by a deviation D from its original value. The same applies to the second embodiment.

[0118] In the first embodiment, in step S13 of the standard value adjustment process, as in step S24 of the standard value adjustment process in the second embodiment, the steering side control unit 60 can be triggered by inputting an offset command to set the value of the pinion angle θp at this time to the offset value θofs.

[0119] In the first embodiment, steps S12 and S13 of the standard value adjustment process can be implemented as follows: the steering side control unit 60 calculates the pinion angle θp when the steering wheel 5 is in a forward straight-line state, and automatically updates the offset value θofs, regardless of whether an offset command is input. In this case, step S103 of the standard value adjustment method can be omitted. This also applies to steps S23 and S24 of the standard value adjustment process in the second embodiment. In this case, step S113 of the standard value adjustment method can be omitted.

[0120] In the first embodiment, in the process of determining whether normal steering side control can be properly executed, step S11, this determination can be based on the diagnostic results of the diagnostic tool 45. In this case, the diagnostic tool 45 should output a diagnostic result command to the steering control device 1, i.e., the steering side control unit 60, indicating the result of determining whether normal steering side control can be properly executed. This also applies to the process of step S21 of the standard value adjustment process in the second embodiment.

[0121] In the first embodiment, before step S102, which causes the vehicle to move, the step of adjusting the toe angle of the left and right steering wheels 5 can be added to the standard value adjustment method. In this case, although the standard value θsd may deviate from the rack neutral position due to reasons attributable to the adjustment of the toe angle of the left and right steering wheels 5, this situation can be appropriately addressed. This also applies to the standard value adjustment method of the second embodiment. That is, before and after step S112, which creates a forward straight-moving state for the steering wheels 5 when the vehicle is stationary, the step of adjusting the toe angle of the left and right steering wheels 5 should be added to the standard value adjustment method.

[0122] In the first embodiment, the vehicle can be configured such that a factory mode can be set via special operation by a worker on the vehicle or steering control device 1. In this case, the vehicle can be configured such that an offset command can be input via special operation by a worker on the vehicle or steering control device 1. In these cases, diagnostic tool 45 is not required to adjust the standard value θsd. This also applies to the second embodiment.

[0123] In the first embodiment, the unit quantity can be a value that varies based on the value of the pinion angle θp when the steering wheel 5 is in a forward straight-line state (i.e., the magnitude of the deviation from the standard value θsd). For example, the unit quantity can be a value obtained by dividing the value of the pinion angle θp when the steering wheel 5 is in a forward straight-line state by a predetermined integer n.

[0124] In the second embodiment, in step S24 of the standard value adjustment process, as in step S13 of the standard value adjustment process in the first embodiment, the steering side control unit 60 can be triggered by inputting an offset command to update the offset value θofs by increasing or decreasing the offset value θofs by a unit amount.

[0125] In each of the above embodiments, the standard value adjustment process can be implemented as a process in which the steering control side control unit 50 and the steering side control unit 60 cooperate with each other. For example, the processes of steps S10 and S11 can be assigned to the steering control side control unit 50, and the processes of other steps S12 to S15 can be assigned to the steering side control unit 60. In this case, the steering control side control unit 50 and the steering side control unit 60 correspond to control units. This also applies to the standard value adjustment process of the second embodiment.

[0126] In each of the above embodiments, the diagnostic tool 45 can be configured to allow a worker to check the value of the pinion angle θp. In this case, the steering side control unit 60 should be configured to output the value of the pinion angle θp to the diagnostic tool 45 when the factory mode is set.

[0127] In each of the above embodiments, the notification device that informs the driver that the factory mode has been set, i.e., the standard value θsd is being adjusted, can be located inside the vehicle, for example, in the dashboard. Examples of notification actions by the notification device include displaying a message via characters, issuing a message via voice, or generating an electronic sound.

[0128] In each of the above embodiments, the steering angle ratio is set to an appropriate value according to product specifications, etc. For example, the steering angle ratio can be θh∶θi, i.e., θh∶θp = 1∶1 or 1∶3. When θh∶θp is 1∶3, a 10° change in the steering angle θh is accompanied by a 30° change in the steering angle θi. When θh∶θp is 1∶1, the steering conversion angle θp_s is substantially matched with the pinion angle θp. In either case, unless the standard value θsd deviates from the rack neutral position, the pinion angle θp is zero when the steering wheel 5 is in the forward straight-line state.

[0129] In each of the above embodiments, the steering control device 1 may have a control unit configured to integrate the functions of the steering control side control unit 50 that operates the steering control side motor 13 and the steering control side control unit 60 that operates the steering side motor 32.

[0130] In each of the above embodiments, when calculating the target reaction torque, the steering control unit 50 should at least use a state variable that changes according to the operating state of the steering wheel 3. In this case, instead of using vehicle speed V or steering torque Th, the steering control unit 50 may use other elements or combinations of other elements.

[0131] In each of the above embodiments, the steering control side control unit 50 can calculate the value as the target reaction torque by performing torque feedback control that adapts the steering torque Th to the target steering torque calculated based on the steering torque Th.

[0132] In each of the above embodiments, the steering control side control unit 50 can calculate the steering angle θh by taking into account the torsion of the steering shaft 11 corresponding to the steering torque Th and incorporating the torsion into the rotation angle θa by addition, subtraction, etc.

[0133] In each of the above embodiments, the steering angle θh can be obtained from the detection result of a steering control sensor installed on the steering control shaft 11 to detect the rotation angle of the steering control shaft 11.

[0134] In each of the above embodiments, the pinion angle θp can be determined using the detection result of a pinion angle sensor mounted on the pinion shaft 21 to detect the rotation angle of the pinion shaft 21. In each of the above embodiments, the steering-side motor 32 can be, for example, a motor mounted on the same axis as the rack shaft 22, or a motor connected to the pinion shaft forming part of the rack and pinion mechanism via a worm and worm wheel on the rack shaft 22.

[0135] In each of the above embodiments, the steering control device 2 has a linkageless structure in which the steering control unit 4 and the steering unit 6 are always mechanically separated from each other. However, the steering control device 2 is not limited to this and may have a structure in which the steering control unit 4 and the steering unit 6 can be mechanically separated by a clutch. Furthermore, the steering control device 2 may have a structure in which the steering unit 6 can independently steer the left steering wheel and the right steering wheel 5. Additionally, the steering control device 2 may be an electric steering control device that applies an auxiliary force as a force to assist the driver in steering operations. In this case, the pinion shaft 21 is mechanically connected to the steering wheel 3 via the steering control shaft 11. The steering control shaft 11 is mechanically connected to the pinion shaft 21 via a steering angle ratio variable mechanism that changes the steering angle ratio. The electric steering control device that can change the steering angle ratio can be configured such that when feedback control is performed on the pinion angle θp, the standard value θsd of each of the above embodiments can be adjusted. In this case, even if the same problem occurs as in each of the above embodiments, the problem can be solved by applying the configuration according to each of the above embodiments.

Claims

1. A steering control device (1) that controls a steering device (2) as a target, the steering device (2) including a steering unit (6) that operates to turn the steering wheels of a vehicle, the steering control device (1) characterized in that it includes a control unit (60) that stores standard values ​​and controls the operation of the steering unit (6), the standard values ​​being values ​​associated with a mechanical state of the steering unit representing a forward straight-ahead state, the forward straight-ahead state being the steering state of the steering wheels (5) when the vehicle is moving forward straight, wherein: The control unit (60) is configured to perform control angle calculation processing, angle feedback processing, and standard value adjustment processing; The control angle calculation process is a process of calculating a control angle as an absolute angle relative to the standard value, wherein the control angle is angle information representing the actual steering state of the steering wheel (5), and the angle feedback process is a process of performing feedback control on the control angle to make the steering wheel (5) turn to the target steering state, and the standard value adjustment process is a process of adjusting the stored standard value in the event of a diagnostic state for diagnosing an abnormal state of the vehicle. as well as The standard value adjustment process includes the following steps: when the control angle deviates from the value representing the forward straight-ahead state in the forward straight-ahead state, the standard value is adjusted to reduce the deviation between the control angle and the value representing the forward straight-ahead state. The standard value adjustment process includes: The process of obtaining a value as an offset value by accumulating a unit quantity, wherein the unit quantity is a smaller value than the value representing the deviation of the control angle from the value representing the forward straight-ahead state in the forward straight-ahead state; and The process involves gradually adjusting the standard value in units until it becomes the obtained offset value.

2. The steering control device (1) according to claim 1, characterized in that, The standard value adjustment process includes the following steps: setting an upper limit for the absolute value of the offset value.

3. The steering control device (1) according to claim 1 or 2, characterized in that: The control unit (60) is configured to perform the standard value adjustment process during vehicle operation when the diagnostic state occurs.

4. The steering control device (1) according to claim 1 or 2, characterized in that: The control unit (60) is configured to perform the standard value adjustment process when the vehicle is stationary in the event of the diagnostic state.

5. A standard value adjustment method for adjusting a standard value, the standard value being information stored in a control unit (60) belonging to a steering control device (1), the steering control device (1) controlling a steering device (2) as a target, the steering device (2) including a steering unit (6) that operates to turn the steering wheels (5) of a vehicle, the standard value being a value associated with a mechanical state of the steering unit (6) representing a forward straight-ahead state, the forward straight-ahead state being the steering state of the steering wheels (5) when the vehicle is moving forward straight, the standard value adjustment method being characterized by comprising: Diagnostic status setting steps, in which: When the control unit (60) calculates the control angle as an absolute angle relative to the standard value, the standard value is used, wherein the control angle is angle information representing the actual steering state of the steering wheel; When the control unit (60) performs feedback control to turn the steering wheel (5) to the target steering state while controlling the operation of the steering unit (6), the control angle is used as the control quantity; as well as The diagnostic status for diagnosing abnormal conditions of the vehicle is set by operating a diagnostic tool connected to the vehicle from the outside. as well as The standard value adjustment step, in which the diagnostic state is set, adjusts the standard value stored in the control unit (60), wherein the standard value adjustment step includes the following steps: when the control angle deviates from the value representing the forward straight-ahead state in the forward straight-ahead state, the standard value is adjusted by operating the diagnostic tool so that the deviation between the control angle and the value representing the forward straight-ahead state is reduced. The standard value adjustment steps include: The step of obtaining a value as an offset value by accumulating a unit quantity, wherein the unit quantity is a smaller value than the value representing the deviation of the control angle from the value representing the forward straight-ahead state in the forward straight-ahead state; and The step of gradually adjusting the standard value in units until it becomes the obtained offset value.

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