EPS Steering Torque Compensation for Low-Adhesion Roads
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Solution Overview
Problem
Existing EPS assist torque adjustment methods based on steering wheel angle lookup tables fail to adapt to low-adhesion roads, leading to excessive steering holding torque compensation and abnormal steering feel, compromising driving safety.
Innovation Solution
Adaptive steering holding torque compensation method that adjusts the compensation value based on road adhesion coefficient changes using a preset algorithm, limiting the steering holding torque compensation integral value and attenuation coefficient with rack force as an influencing factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EPS assist torque adjustment method based on steering wheel angle lookup tables is used, then steering holding torque is improved under high-adhesion roads, but steering holding torque becomes excessively light and overcompensated under low-adhesion roads
Solution Approach 1:
The patent transforms the static lookup table method into a dynamic compensation method by introducing rack force as a real-time variable. The steering holding torque compensation value is dynamically adjusted based on the relationship between rack force and steering wheel angle, allowing the system to adapt to varying road adhesion conditions rather than relying on pre-defined static tables.
Solution Approach 2:
The patent implements feedback control by using rack force information to continuously adjust the steering holding torque compensation value. The control unit monitors rack force in real-time and modifies the compensation output accordingly, creating a closed-loop system that automatically adapts to changing road conditions without requiring manual intervention or reconfiguration.
2Ease of operation
If steering holding torque compensation value is increased to improve steering feel under high-adhesion roads, then steering holding torque becomes excessively heavy under low-adhesion roads
Solution Approach 1:
The patent changes the key parameter from steering wheel angle alone to a combination of rack force and steering wheel angle. By using rack force as the primary basis for compensation adjustment, the system automatically scales the compensation magnitude according to actual road conditions, preventing both overcompensation and undercompensation across different adhesion scenarios.
Data Source
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AI summary
A steering moment compensation method and apparatus, a medium, and a vehicle. The steering moment compensation method comprises: acquiring a steering wheel angle, a vehicle speed and a rack force of a vehicle; on the basis of the steering wheel angle, the vehicle speed and the rack force, determining a steering moment compensation integral value by using a preset steering moment compensation algorithm, wherein the steering moment compensation integral value is used for representing an absolute value of a steering moment compensation value, and the preset steering moment compensation algorithm is used for limiting an upper limit value of the steering moment compensation integral value, and under the steering moment working condition, enabling the steering moment compensation integral value to reach the upper limit value and to decrease along with decrease of the absolute value of the rack force; and multiplying the steering moment compensation integral value by a positive/negative symbol of the rack force to obtain the steering moment compensation value. According to the compensation method, the steering moment compensation value can be adaptively adjusted along with the change of a road adhesion coefficient, thereby avoiding the problem of excessive steering moment compensation on a low-adhesion road, and ensuring the driving safety.