Steering Control System End-of-Travel Harshness Reduction
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Solution Overview
Problem
Current vehicle steering systems experience harsh, abrupt feelings when steering into corners due to metal-on-metal clunk in the steering rack end of travel hardware, leading to both audible and tactile annoyances, which existing solutions often cannot address cost-effectively or timely due to deficiencies in rack and pinion travel stop compliance.
Innovation Solution
A control system for the steering system that includes modules to determine a gain curve based on the hand wheel position, adjusting motor assist commands to reduce end-of-travel harshness by applying gain and damping values, with specific gain and damping curves defined for entering, exiting, and operating within the end-of-travel region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If rack and pinion travel stop compliance is modified to reduce end-of-travel harshness, then subjective steering impression improves, but cost and development time increase
Solution Approach 1:
The patent replaces mechanical modifications to the rack and pinion travel stops with an electronic control system. The ECU receives steering angle sensor signals and dynamically adjusts motor assist torque based on detected end-of-travel conditions, eliminating the need for physical hardware changes while reducing cost and development time.
Solution Approach 2:
The system changes the steering assist parameter (motor torque) dynamically based on steering angle position. When end-of-travel is detected through the steering angle sensor, the ECU modifies the assist torque parameter to reduce harshness, providing adaptive control without mechanical complexity.
2Ease of operation
If motor assist torque is increased to improve steering effort, then steering ease improves, but end-of-travel harshness worsens
Solution Approach 1:
The system dynamically adjusts motor assist torque based on real-time steering angle position. The ECU continuously monitors the steering angle sensor and modifies the assist torque level, providing high assist during normal operation while reducing assist near end-of-travel positions to eliminate harshness.
Solution Approach 2:
The system uses feedback from the steering angle sensor to continuously monitor steering position and adjust motor torque accordingly. When the steering angle indicates approach to end-of-travel, the ECU receives this feedback and reduces motor assist to prevent harshness, creating a closed-loop control system.
Data Source
AI summary
A control system for controlling a steering system is provided. The control system includes a first module that selectively determines a gain curve based on a position of a hand wheel of the steering system. A second module determines a motor assist command based on the gain curve.