US-12617456-B2 - Steering control device

US12617456B2US 12617456 B2US12617456 B2US 12617456B2US-12617456-B2

Abstract

A steering control device includes: a target rotation angle calculation circuit that calculates a target rotation angle of a shaft; an offset angle calculation circuit that calculates an offset angle relative to the target rotation angle; a final target rotation angle calculation circuit that calculates a final target rotation angle of the shaft; and a feedback control circuit that executes feedback control that adapts a real angle to the final target rotation angle. The offset angle calculation circuit calculates an estimated rotation angle deviation based on a value of a current of a turning motor immediately before a specific event occurs, and calculates the offset angle by subtracting the real angle and the estimated rotation angle deviation from the target rotation angle.

Inventors

Junya MIYAKE
Toru Takashima
Hidetsugu TOYAMA

Assignees

JTEKT CORPORATION
TOYOTA JIDOSHA KABUSHIKI KAISHA

Dates

Publication Date: 20260505
Application Date: 20241021
Priority Date: 20231027

Claims (7)

1 . A steering control device configured to control electric power supply to a turning motor that drives a steering device that turns a turning wheel of a vehicle, the steering control device comprising: a target rotation angle calculation circuit configured to calculate, according to a steering angle of a steering wheel, a target rotation angle of a shaft that rotates in conjunction with a turning action of the turning wheel; an offset angle calculation circuit configured to calculate an offset angle relative to the target rotation angle when a specific event occurs in a state where there is a discrepancy between the target rotation angle and a real angle of the shaft; a final target rotation angle calculation circuit configured to calculate a final target rotation angle of the shaft by subtracting the offset angle from the target rotation angle; and a feedback control circuit configured to execute feedback control that adapts the real angle to the final target rotation angle; wherein the offset angle calculation circuit is configured to calculate an estimated rotation angle deviation based on a value of a current of the turning motor immediately before the specific event occurs, and is configured to calculate the offset angle by subtracting the real angle and the estimated rotation angle deviation from the target rotation angle.
2 . The steering control device according to claim 1 , wherein the offset angle calculation circuit is configured to gradually reduce the offset angle toward zero after calculating the offset angle.
3 . The steering control device according to claim 1 , wherein: the feedback control circuit is configured to execute proportional control that controls the real angle in proportion to a deviation of the real angle from the final target rotation angle; and when the estimated rotation angle deviation is “Δθ p {circumflex over ( )},” the value of the current of the turning motor immediately before the specific event occurs is “I b ,” a proportional gain of the feedback control circuit is “G p ,” a rated current of the turning motor is “I t ,” and a rated pinion torque is “T p ,” the offset angle calculation circuit is configured to calculate the estimated rotation angle deviation based on the following Formula (A): Δθ p ⋀ = I b / { G p · I t / T p } ( A )
4 . The steering control device according to claim 1 , wherein the specific event is that execution of a current restriction process in which a current supplied to the turning motor is restricted is ended.
5 . The steering control device according to claim 1 , wherein the specific event is that a power source of the vehicle is turned on.
6 . The steering control device according to claim 1 , wherein the steering device is a steer-by-wire steering device in which power transmission between the steering wheel and the turning wheel is cut off.
7 . The steering control device according to claim 1 , wherein the steering device is an electric power steering device in which the steering wheel and the turning wheel are coupled to each other so as to transmit power, and the electric power steering device has a variable-gear-ratio function of changing a steering gear ratio that is a ratio of a turning angle of the turning wheel to the steering angle of the steering wheel.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to Japanese Patent Application No. 2023-184775 filed on Oct. 27, 2023. The disclosure of the above-identified application, including the specification, drawings, and claims, is incorporated by reference herein in its entirety. BACKGROUND 1. Technical Field The present disclosure relates to a steering control device. 2. Description of Related Art There is a so-called steer-by-wire steering device in which power transmission between a steering wheel and turning wheels is cut off. The steering device includes a reaction force motor that is a generation source of a steering reaction force to be applied to a steering shaft, and a turning motor that is a generation source of a turning force for turning the turning wheels. A control device of the steering device generates the steering reaction force through control of electric power supply to the reaction force motor, and turns the turning wheels through control of electric power supply to the turning motor. For example, the control device of Japanese Unexamined Patent Application Publication No. 2020-83059 (JP 2020-83059 A) executes an output restriction process that restricts an output of a turning motor when an output restriction condition is met. Examples of the output restriction condition include that a temperature of the turning motor exceeds a temperature threshold value, and that a voltage supplied to the turning motor falls below a voltage threshold value. Through the execution of the output restriction process, a temperature rise of the turning motor or power consumption of the turning motor is restricted. SUMMARY In conventional control devices having the function of restricting the output of the turning motor, including the control device of JP 2020-83059 A, there is a concern as follows: When the restriction on the output of the turning motor is canceled as the output restriction condition fails to be met or a specified output restriction cancelation condition is met, the output of the turning motor may change rapidly. A rapid change in the output of the turning motor constitutes a factor in causing abnormal sound or vibration. One aspect of the present disclosure is a steering control device. The steering control device is configured to control electric power supply to a turning motor that drives a steering device that turns a turning wheel of a vehicle. The steering control device includes: a target rotation angle calculation circuit or unit configured to calculate, according to a steering angle of a steering wheel, a target rotation angle of a shaft that rotates in conjunction with a turning action of the turning wheel; an offset angle calculation circuit or unit configured to calculate an offset angle relative to the target rotation angle when a specific event occurs in a state where there is a discrepancy between the target rotation angle and a real angle of the shaft; a final target rotation angle calculation circuit or unit configured to calculate a final target rotation angle of the shaft by subtracting the offset angle from the target rotation angle; and a feedback control circuit or unit configured to execute feedback control that adapts the real angle to the final target rotation angle. The offset angle calculation circuit or unit is configured to calculate an estimated rotation angle deviation based on a value of a current of the turning motor immediately before the specific event occurs, and is configured to calculate the offset angle by subtracting the real angle and the estimated rotation angle deviation from the target rotation angle. According to this configuration, when the specific event occurs, the final target rotation angle does not match the present value of the real angle of the shaft. Therefore, while the absolute value of the current supplied to the turning motor decreases rapidly, the absolute value of the current supplied to the turning motor does not instantly reach “0.” Thus, a rapid change in the output of the turning motor and, by extension, a rapid change in the turning angle of the turning wheel due to the absolute value of the current supplied to the turning motor instantly reaching “0” can be made less likely. In the above-described steering control device, the offset angle calculation circuit may be configured to gradually reduce the offset angle toward zero after calculating the offset angle. According to this configuration, the real angle of the shaft can be adapted to the final target rotation angle while a rapid change in the output of the turning motor is made less likely. In the above-described steering control device, the feedback control circuit may be configured to execute proportional control that controls the real angle in proportion to a deviation of the real angle from the final target rotation angle. When the estimated rotation angle deviation is “Δθp{circumflex over ( )}” the value of the current of the turning motor immediately