Steering End-Position Updating for End Strike Relaxation Control
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Solution Overview
Problem
Existing electric power steering systems (EPS) face challenges in accurately determining the end position corresponding angles, leading to insufficient reduction of end strike impact due to deviations between stored and actual angles, especially after vehicle repairs.
Innovation Solution
A steering control device that includes an electronic control unit to detect absolute steering angles, compute current command values for motor torque, and execute end strike relaxation control by updating end position corresponding angles based on restriction position determination angles, thereby reducing deviations and improving vehicle performance during sharp turns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If end strike relaxation control is executed using stored end position corresponding angles, then the impact of end strike is reduced, but the stored angles may deviate from actual end angles causing insufficient torque reduction
Solution Approach 1:
The system performs preliminary action by detecting and storing restriction position determination angles when the steered shaft actually contacts the housing during normal operation. These detected angles are then used to correct the stored end position corresponding angles, ensuring they accurately reflect actual end positions before subsequent end strike relaxation control is executed.
Solution Approach 2:
The system implements feedback by continuously monitoring the absolute steering angle and comparing it with the stored end position corresponding angles. When deviation is detected between stored angles and actual restriction positions, the system feeds back correction information to update the stored angles, creating a closed-loop system that maintains accuracy.
2Measurement precision
If the end position corresponding angle is updated based on restriction position determination angle, then deviation is reduced, but additional control complexity is introduced
Solution Approach 1:
The system applies self-service by automatically detecting restriction positions during normal steering operations and autonomously updating its own end position corresponding angles without requiring external calibration procedures or manual intervention. The electronic control unit performs both the detection and update functions using existing sensors and processors.
Solution Approach 2:
The system uses partial action by selectively updating only those end position corresponding angles that show deviation beyond a predetermined threshold, rather than continuously updating all angles. This approach reduces computational overhead while maintaining sufficient accuracy for end strike relaxation control.
3Object-affected harmful factors
If the steered shaft is constrained to prevent end strike, then housing damage is prevented, but vehicle performance during sharp turns is impaired
Solution Approach 1:
The system changes the parameter of motor torque dynamically based on the detected end separation angle. When the steering angle approaches the end position corresponding angle, the motor torque is gradually reduced to prevent end strike. However, when restriction position determination indicates actual end contact, the system updates the reference angles to allow future excursions that maintain safe margins without unnecessarily limiting turning performance.
Solution Approach 2:
The system applies dynamics by making the end position corresponding angles adaptive rather than fixed. The angles are continuously refined based on actual operational data from restriction position determination, allowing the control parameters to evolve with usage patterns and maintain optimal balance between protection and performance.
Data Source
AI summary
A steering control device includes an electronic control unit that stores an end position corresponding angle. The electronic control unit is configured to execute end strike relaxation control, to execute partial release control in a case where turning of a vehicle is attempted during execution of the end strike relaxation control, to make a non-following determination and acquire a release-time restriction position determination angle that corresponds to the absolute steering angle detected at a time when the electronic control unit determines that the movement of the steered shaft is restricted, and to permit update of the end position corresponding angle based on the release-time restriction position determination angle, and update the end position corresponding angle in a case where the update of the end position corresponding angle is permitted.