Four-Wheel Steering Control for Target Line Tracing
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Solution Overview
Problem
Existing vehicle steering systems struggle to effectively integrate automated driving techniques with manual steering, particularly in enhancing the utility of four-wheel steering systems by independently controlling front and rear wheels to maintain a target travel line.
Innovation Solution
A steering system that includes a controller to determine a driving support force for the front wheels based on the target operation amount and rear-wheel steering amount, incorporating a feedforward and feedback component to enhance line trace control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the driving support force is determined only based on the target operation amount, then the control is simple, but the line trace behavior is poor
Solution Approach 1:
The patent implements feedback by incorporating the rear-wheel steering amount into the determination of the driving support force. The controller continuously monitors the actual rear-wheel steering amount and uses this feedback information to adjust the driving support force, thereby improving line trace behavior while maintaining appropriate control complexity through systematic integration of multiple sensor inputs.
Solution Approach 2:
The patent applies preliminary action by proactively determining the driving support force based on both the target operation amount and the current rear-wheel steering amount before the vehicle deviates from the target travel line. This predictive approach allows the system to compensate for potential deviations and maintain precise line trace behavior.
2Manufacturing precision
If the driving support force is determined based on both target operation amount and rear-wheel steering amount, then the line trace behavior is improved, but the control calculation becomes more complex
Solution Approach 1:
The system uses feedback from the rear-wheel steering amount sensor to continuously adjust the driving support force calculation. By integrating this feedback loop, the controller achieves improved line trace behavior through dynamic adjustment of the driving support force based on actual vehicle state, while managing calculation complexity through systematic processing of multiple inputs.
Solution Approach 2:
The controller performs multiple functions by simultaneously processing both the target operation amount from the operation member and the rear-wheel steering amount from the rear-wheel steering device to determine the driving support force. This multi-functional approach consolidates control calculations within a single controller, improving line trace behavior while distributing the computational load across integrated control algorithms.
Data Source
AI summary
A steering system for a vehicle includes: an operation member operable by a driver; a front-wheel steering device to which the operation member is connected to enable a front wheel to be steered by a steering amount; a rear-wheel steering device configured to steer a rear wheel independently of the front wheel; and a controller configured to control the front-wheel and rear-wheel steering devices. The controller executes a front-wheel steering force application control to apply, to the front wheel, a steering force including, as a component thereof, a driving support force that causes the vehicle to travel along a target travel line. The controller determines, in the front-wheel steering force application control, the driving support force based on a target operation amount that is the operation amount of the operation member to cause the vehicle to travel along the target travel line and a steering amount of the rear wheel.