Vehicle Control System Feed-Forward Correction for Stability
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Solution Overview
Problem
Existing rear wheel steering control systems face stability issues when both feed-forward and feedback controls are used in limit driving conditions due to excessive control amounts, which can lead to vehicle instability.
Innovation Solution
A vehicle control system that includes a feed-forward computing unit, a feedback computing unit, and a correcting unit to adjust the feed-forward control amounts based on feedback control, using degenerate gains to prevent excessive control actions, particularly in the rear wheel steering, power distribution, brake, and damper systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If both feed-forward control and feedback control are used together in limit driving condition range, then the vehicle behavior can be controlled, but the control amount increases excessively and vehicle stability cannot be maintained
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the feed-forward control amount based on the feedback control amount. When the feedback control amount increases (indicating approaching limit driving conditions), the feed-forward control amount is reduced proportionally. This parameter adjustment prevents excessive total control amount while maintaining effective vehicle behavior control throughout the operating range.
2Ease of operation
If the front wheel steering angle is increased in limit driving condition, then the feed-forward control amount significantly increases, but vehicle stability is compromised
Solution Approach 1:
The patent implements feedback control by continuously monitoring the actual vehicle state (yaw rate, slip angle) and comparing it with target values. The feedback control amount is computed from the deviation between target and actual states. This feedback mechanism detects when the vehicle approaches limit driving conditions and triggers the reduction of feed-forward control amount, thereby preventing instability while allowing full steering angle range for ease of operation.
Data Source
AI summary
A vehicle control system (30) for controlling a behavior control device (20) that controls a behavior of a vehicle (1), comprising: a feed-forward computing unit (71) that computes a feed forward control amount of the behavior control device according to a steering angle of the vehicle; a feedback computing unit (72) that computes a feedback control amount of the behavior control device according to a difference between a target vehicle state amount computed from the steering angle and an actual vehicle state amount; a correcting unit (73) that computes a corrected feed-forward control amount by correcting the feed forward control amount according to the feedback control amount; and a target control amount computing unit (74) that computes a target control amount of the behavior control device according to the feedback control amount and the corrected feed forward control amount.