Brake-by-wire Steering Coordination for Failure Stability
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Solution Overview
Problem
Brake-by-wire (BBW) systems face challenges in maintaining braking performance and stability when one of its devices fails, leading to partial braking and reduced maximum braking force, especially during rapid turns or when only two BBW devices are operational.
Innovation Solution
The integration of a steer-by-wire (SBW) controller and a rear wheel steering (RWS) controller to control the vehicle's steering and braking forces, using three electro-mechanical brakes when one BBW device fails, and adjusting steering angles to compensate for understeer or oversteer conditions by determining an understeer determination coefficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If braking force is generated by three BBW devices when one fails, then maximum braking force is maintained, but steering stability performance deteriorates during rapid turns
Solution Approach 1:
The system dynamically switches between different braking configurations based on failure detection. When a BBW device fails, the system transitions from using all four BBW devices to using three, and further to using only two (front or rear) based on the understeer determination coefficient, allowing adaptive response to maintain both braking force and steering stability
Solution Approach 2:
The system changes the operational parameters of the BBW devices based on the failure state and vehicle behavior. By monitoring the understeer determination coefficient and adjusting which BBW devices remain active, the system optimizes the balance between maintaining braking force and preserving steering stability during failure conditions
2Stability of the object's composition
If braking force is generated by only front or rear BBW devices, then steering stability performance is improved, but required braking force cannot be generated
Solution Approach 1:
The system dynamically selects between front-wheel-only and rear-wheel-only braking configurations based on the understeer determination coefficient. This dynamic selection allows the system to provide adequate braking force while maintaining steering stability by choosing the appropriate wheel configuration based on real-time vehicle behavior assessment
3Device complexity
If partial braking occurs due to BBW device failure, then device complexity is reduced, but braking performance deteriorates
Solution Approach 1:
The system continuously monitors the operational status of BBW devices and the vehicle's braking behavior through the understeer determination coefficient. This feedback mechanism allows the control system to detect failures and adjust the braking configuration accordingly, maintaining braking performance despite the reduced number of functional BBW devices
Solution Approach 2:
The braking system automatically adapts to failure conditions without external intervention. The control system detects BBW device failures and self-adjusts the braking configuration by selecting appropriate combinations of remaining functional devices, ensuring continued braking performance while managing the reduced system capability
Data Source
AI summary
A system and a method of improving a braking performance during a failure of a brake-by-wire (BBW) device, includes BBW devices including electro-mechanical brakes provided for respective wheels of a vehicle and independently performing braking, and the BBW devices including controllers electrically connected to the electro-mechanical brakes, and the system includes a steer-by-wire controller configured for controlling front wheels through an electronic signal and a rear wheel steering (RWS) controller configured for controlling steering of rear wheels such that a rear wheel steering angle is to be controlled in the same or an antiphase of a front wheel steering angle, wherein when one of the controllers fails, at least one of the steer-by-wire controller and the RWS controller is configured to control steering based on whether a driver's required braking force exceeds a maximum braking force which may be generated by any one of the front and rear wheels.