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EP-4470882-B1 - STEERING CONTROL DEVICE

EP4470882B1EP 4470882 B1EP4470882 B1EP 4470882B1EP-4470882-B1

Inventors

  • HOSONO, HIROSHI
  • TAMAIZUMI, TERUTAKA
  • INDEN, YUKI
  • TAKAHASHI, SAKI

Dates

Publication Date
20260513
Application Date
20240529

Claims (6)

  1. A steering control device (50) configured to control, as an object of control, a steering system including a reaction force motor (22) that applies a steering reaction force to a steering shaft (14) and a turning motor (42) that turns a turning wheel (34) in a state where power transmission from the steering shaft (14) is cut off, the steering control device comprising a processor (52) configured to execute reaction force setting processing, reaction force application processing, and axial force gradient calculation processing, wherein the reaction force setting processing is processing of setting the steering reaction force using phase compensation processing, the reaction force application processing is processing of operating the reaction force motor (22) with a reaction force set by the reaction force setting processing as input thereto, the phase compensation processing is processing of performing phase compensation on the steering reaction force, the axial force gradient calculation processing is processing of calculating an axial force gradient, the axial force gradient is a variable indicating a ratio of a change in resisting force against rotation of the steering shaft (14) to a change in rotation angle of the steering shaft (14), characterized in that the processor (52) is further configured to execute interlocking processing, wherein the interlocking processing is processing of changing one of both a value of a phase compensation regulation variable and the axial force gradient according to the other, and the phase compensation regulation variable is a variable that regulates a manner of the phase compensation.
  2. The steering control device (50) according to claim 1, wherein the reaction force setting processing includes assist amount setting processing and axial force setting processing, the axial force setting processing is processing of setting an axial force that is a resisting force against a rotating operation of the steering shaft (14) by a driver, the assist amount setting processing is processing that includes the phase compensation processing and sets an assist amount, the assist amount is an amount of assisting the driver to rotate the steering shaft (14), the steering reaction force is an amount determined according to a value obtained by subtracting the assist amount from the axial force, and the axial force gradient calculation processing is processing of calculating a change amount of the axial force set by the axial force setting processing with respect to the change in the rotation angle of the steering shaft (14).
  3. The steering control device (50) according to claim 1, wherein the interlocking processing is processing of changing a value of the phase compensation regulation variable with the axial force gradient as input.
  4. The steering control device (50) according to claim 2, wherein the assist amount setting processing is processing of setting the assist amount according to a detection value of steering torque input to the steering shaft (14), the phase compensation processing includes phase lag compensation processing, the phase lag compensation processing is processing of delaying a phase of the detection value and inputting the phase-delayed detection value to the assist amount setting processing, the phase compensation regulation variable includes a lag regulation variable, the lag regulation variable is a variable for regulating the phase lag compensation processing, and the interlocking processing includes processing of changing a value of the lag regulation variable with the axial force gradient as input.
  5. The steering control device (50) according to claim 2, wherein the assist amount setting processing includes basic assist amount setting processing, the basic assist amount setting processing is processing of setting a basic assist amount according to a detection value of steering torque input to the steering shaft (14), the phase compensation processing includes phase advance compensation processing, the phase advance compensation processing is processing of calculating an advance correction amount of the basic assist amount with the detection value as input, the assist amount setting processing is processing of setting the assist amount according to a value obtained by correcting the basic assist amount with the advance correction amount, the phase compensation regulation variable includes advance regulation variable, the advance regulation variable is a variable for regulating the phase advance compensation processing, and the interlocking processing includes processing of changing the value of the advance regulation variable with the axial force gradient as input.
  6. The steering control device (50) according to claim 2, wherein the axial force setting processing includes processing of setting the axial force according to a value of an axial force regulation variable, the axial force regulation variable is a variable for regulating a relationship of the axial force to a value of an angle variable of the steering system, and the interlocking processing includes processing of changing the value of the axial force regulation variable with the value of the phase compensation regulation variable as input.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present disclosure relates to a steering control device. 2. Description of Related Art For example, Japanese Unexamined Patent Application Publication No. 2017-144887 described below describes a control device for controlling an electric power steering device as a control target. This control device sets the torque of a motor for generating assist force by using phase compensation processing. This setting is aimed at stabilizing the system. EP 3 219 580 A1 discloses a steering control apparatus that allows steering feel resulting from transmission of road surface information to a steering wheel to be easily adjusted. SUMMARY OF THE INVENTION The inventor has studied control of a steering system in a state where power transmission between a steering shaft and turning wheels is cut off. In that case, the degree of freedom in adjusting the characteristics of the steering system by control is high. However, when the characteristics of the steering system are arbitrarily set, there is a risk that an effect of stabilization by phase compensation processing may be impaired. A steering control device according to a first aspect of the present disclosure is configured to control, as an object of control, a steering system including a reaction force motor that applies steering reaction force to a steering shaft and a turning motor that turns turning wheels in a state where power transmission from the steering shaft is cut off. The steering control device includes a processor. The processor is configured to execute reaction force setting processing, reaction force application processing, axial force gradient calculation processing, and interlocking processing. The reaction force setting processing is processing of setting the steering reaction force by using phase compensation processing. The reaction force application processing is processing of operating the reaction force motor with the reaction force set by the reaction force setting processing being used as input. The phase compensation process is processing of performing phase-compensation on the steering reaction force. The axial force gradient calculation processing is processing of calculating an axial force gradient. The axial force gradient is a variable indicating a ratio of the change in resisting force against rotation of the steering shaft to the change in a rotation angle of the steering shaft. The interlocking processing is processing of changing one of the value of a phase compensation regulation variable and the axial force gradient according to the other of the phase compensation regulation variable and the axial force gradient. The phase compensation regulation variable is a variable for regulating a manner of the phase compensation. The magnitude of the axial force gradient at which the phase compensation processing effectively functions changes according to the settings such as the time constant of the phase compensation processing. Therefore, in the above configuration, one of both the variable for regulating the manner of phase compensation and the axial force gradient is changed according to the other. This makes it possible to implement phase compensation processing suitable for the magnitude of the axial force gradient. In the steering control device according to a first aspect of the present disclosure, the reaction force setting processing may include assist amount setting processing, and axial force setting processing. The axial force setting processing may be processing of setting axial force which is a resisting force against a rotational operation of the steering shaft by a driver. The assist amount setting processing may be processing that includes the phase compensation processing and sets an assist amount. The assist amount may be an amount that assists the driver in rotating the steering shaft. The steering reaction force may be an amount that is determined according to a value obtained by subtracting the assist amount from the axial force. The axial force gradient calculation processing may be processing of calculating an amount of change in the axial force set by the axial force setting processing with respect to a change in the rotation angle of the steering shaft. In a steering system in which power is transmitted between a steering shaft and turning wheels, the axial force from the turning wheels acts as a force for impeding rotating the steering shaft by the driver. Therefore, the assist amount is an amount for assisting the driver's steering. On the other hand, in the above configuration, in a state where power transmission between the steering shaft and the turning wheels is cut off, an axial force that virtually resists the rotational operation of the steering shaft can be implemented through control. Therefore, the assist amount can be set based on the same concept as the steering system in which power is transmitted between the steering shaft and the turning whee