Steering Assist Torque Control for Excessive Initial Turn Speed
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Solution Overview
Problem
Conventional steering assist devices struggle to maintain the driver's sense of independence while ensuring the steering amount is optimal, and the initial steering speed during turning can become excessive.
Innovation Solution
A vehicle steering assist device that includes a control unit to calculate a target steering angle and torque based on road curvature and vehicle speed, reducing return torque where the steering angle is smaller than the target, and applying a control steering torque to adjust steering angular velocity, maintaining optimal steering assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the return torque is corrected by the steering guide torque to reduce the steering reaction force, then the ease of operation is improved, but the steering speed at the initial stage of turning becomes excessive
Solution Approach 1:
The steering guide torque is made dynamically adjustable based on steering angular velocity. When the steering angular velocity exceeds a predetermined threshold, the steering guide torque is reduced or deactivated, allowing the return torque to increase naturally and limit excessive steering speed. This dynamic adjustment resolves the contradiction by adapting the assist torque to real-time steering conditions.
Solution Approach 2:
The system continuously monitors the steering angular velocity and uses this feedback to adjust the steering guide torque. When excessive steering speed is detected, the feedback mechanism reduces the steering guide torque to prevent further speed increase. This closed-loop feedback control ensures that steering assistance is provided while preventing excessive steering speed.
2Manufacturing precision
If the steering guide torque is applied to correct the return torque, then the steering amount control precision is improved, but the driver's sense of independence deteriorates
Solution Approach 1:
The steering guide torque is applied partially rather than continuously. It is activated only when the steering angular velocity is within the normal range and steering assistance is needed. When the steering angular velocity exceeds the threshold, the steering guide torque is reduced or deactivated, preventing excessive intervention that would compromise driver independence. This partial application resolves the contradiction by providing assistance only when necessary.
Solution Approach 2:
The system changes the parameter of steering guide torque magnitude based on steering angular velocity conditions. When steering angular velocity is normal, a larger steering guide torque is applied for precise steering control. When steering angular velocity exceeds the threshold, the steering guide torque parameter is reduced or set to zero, maintaining driver independence. This parameter adjustment resolves the contradiction between precision and independence.
Data Source
AI summary
A vehicle steering assist device in which the steering assist ECU calculates a target steering angle for driving a vehicle along a traveling path, and is vehicle steering assist device that a calculates a target steering guide torque for facilitating the steering angle to become a target steering angle by reducing a return torque for urging the steering wheel to a neutral position in an area where the steering angle is smaller than the target steering angle, wherein when the steering angular velocity is higher than the target steering angular velocity, the steering support ECU calculates a target steering angular velocity control torque acting in a direction opposite to a direction in which the steering angle changes, and controls the control steering torque generating device so as to generate a control steering torque including a sum of the target steering guide torque and the target steering angular velocity control torque.