Vehicle Power Steering Torque Correction for Obstacle Avoidance
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Solution Overview
Problem
Existing vehicle power steering control systems fail to prevent excessive steering operations when avoiding obstacles, leading to unstable and dangerous vehicle situations, as they only increase assist torque in the correction region without adequately managing the steering torque during obstacle avoidance.
Innovation Solution
A vehicle power steering control apparatus that includes a base assist torque setting unit, an obstacle-ahead information detecting unit, and an assist torque correcting unit to predict and adjust the assist torque based on the steering conditions, increasing assist torque when necessary for obstacle avoidance and decreasing it when the obstacle is cleared, thereby controlling the steering torque effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the base assist torque is increased for correction when an obstacle is detected, then the driver can easily make steering operation for avoiding collision with low steering torque, but the vehicle may enter an unstable and dangerous situation due to excessive steering operation
Solution Approach 1:
The assist torque is made dynamic by continuously adjusting it based on real-time monitoring of steering angle and steering rate. The system transitions from a static high torque mode during obstacle detection to a dynamic reduction mode when avoidance is detected, allowing the torque to adapt to the changing steering conditions and prevent excessive steering
Solution Approach 2:
The system implements feedback control by detecting the steering angle and steering rate, comparing them against predetermined thresholds, and adjusting the assist torque accordingly. When the steering operation exceeds the threshold values indicating avoidance maneuver, the system reduces the assist torque to prevent over-steering and maintain vehicle stability
2Ease of operation
If the assist torque is increased only in the increasing region, then the driver gets assistance for steering, but excessive steering by the driver cannot be prevented
Solution Approach 1:
The system applies preliminary anti-action by detecting the tendency toward excessive steering through monitoring steering angle and rate, then preemptively reducing the assist torque before the excessive steering can cause harmful effects. This prevents the harmful effect of over-steering by counteracting it with reduced assistance
Solution Approach 2:
The assist torque characteristic is changed from a static increasing function to a dynamic function that can both increase and decrease based on real-time steering conditions. The system transitions torque from increasing to decreasing mode when avoidance maneuver is detected, allowing prevention of excessive steering while maintaining ease of operation during normal steering
Data Source
AI summary
There is provided a vehicle power steering control apparatus. A steering control unit sets a base assist torque Tb based upon a vehicle speed and a steering torque. When an obstacle ahead is detected by an image recognition device, the steering control unit calculates an overlapping ratio between the obstacle and the vehicle in the widthwise direction. When an absolute value of the overlapping ratio is larger than a predetermined threshold value, the steering control unit increases the base assist torque for correction, and when the absolute value is equal to or smaller than the predetermined threshold value, it decreases the base assist torque for correction. The steering control unit outputs the calculated value to a motor drive unit as a control quantity (assist torque).