4WS Lateral Assistance Control With Rear-Wheel Steering Correction
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Solution Overview
Problem
Existing vehicle steering assistance systems for vehicles with four wheels struggle to effectively account for the steering angle of the rear wheels when correcting the steering of the front wheels, leading to inadequate lane keeping and comfort issues due to independent control systems and lack of consideration for rear wheel dynamics.
Innovation Solution
A method that calculates the steering angle of the front wheels by measuring and incorporating the steering angle of the rear wheels, using gain factors and a dynamic vehicle model to ensure safety and comfort criteria, including transverse correction factors and slip resistance adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If independent control systems are used for front and rear wheels, then safety is improved, but coordination between wheel steering and lane keeping performance deteriorates
Solution Approach 1:
The patent merges the independent front and rear wheel control systems by introducing a coordination module that integrates rear wheel steering angle information into the front wheel steering assistance calculation. This allows both systems to maintain their safety functions while coordinating their actions through shared information processing, resolving the contradiction between independent safety operation and coordinated performance.
Solution Approach 2:
The patent introduces an intermediary coordination mechanism that processes rear wheel steering angle data and uses it to adjust front wheel steering commands. This intermediary layer enables communication and coordination between the otherwise independent control systems, improving lane keeping performance without compromising the safety functions of either system.
2Device complexity
If rear wheel steering angle is not considered in front wheel correction, then control system complexity is reduced, but lane keeping accuracy and dynamic response deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-calculating the relationship between rear and front wheel steering angles through offline gain factor determination. This pre-computation stores coordination parameters that can be quickly applied during real-time operation, adding accuracy without significantly increasing real-time computational complexity.
Solution Approach 2:
The patent changes parameters by introducing gain factors that adjust the influence of rear wheel steering angle on front wheel correction. These parameter adjustments allow the system to adapt the level of coordination based on driving conditions, improving lane keeping accuracy while maintaining manageable system complexity through configurable parameters.
3Speed
If gain factors are determined offline, then real-time calculation speed is improved, but adaptability to different driving conditions deteriorates
Solution Approach 1:
The patent applies dynamics by making the previously static offline-determined gain factors adaptive to real-time driving conditions. The system now adjusts these parameters dynamically based on detected conditions such as vehicle speed and steering angle, maintaining fast real-time calculation while improving adaptability to different driving scenarios.
Data Source
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AI summary
Disclosed is a driving assistance method for a motor vehicle comprising a front-wheel and rear-wheel assistance control system and means for measuring the spatial position and movement of the vehicle, which involves calculating a steering angle of front steered wheels of the vehicle in such a way as to keep the vehicle in a traffic lane based on a dynamic model of the vehicle, characterised in that the method comprises a correction due to the steering of the rear wheels comprising the following sequence of steps: - a step of measuring driving parameters comprising a measurement of the steering angle (δr) of the rear wheels, - an off-line step of determining transverse correction gain factors based on driving safety criteria and driver comfort criteria, - a step of determining a correction (δ4RD) to the steering angle of the front wheels due to the steering of the rear wheels (δr) determined with the measurement of the steering angle of the rear wheels and front wheel steering correction factors (K) from the preceding step.