Steer-by-Wire Fallback via Differential Braking Control
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Solution Overview
Problem
Steering system failures in vehicles, such as those involving steer-by-wire technology, can render vehicles unsafe to operate, as they lack a reliable means to translate driver input into vehicle movement, particularly in cases of actuator failures or disconnects between steering and propulsion systems.
Innovation Solution
A brake-to-steer system that applies varying brake pressure to individual vehicle wheels based on driver input, using algorithms to convert steering requests into brake pressure requests, allowing the vehicle to maintain lateral movement and speed control even when the steer-by-wire system is faulty, by integrating an electronic braking system with the steer-by-wire system and propulsion controls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If steer-by-wire system is used for steering control, then steering precision and automation are improved, but system reliability deteriorates due to actuator failures or disconnects
Solution Approach 1:
The patent introduces a backup steering system using differential braking as an intermediary mechanism. When the primary steer-by-wire system fails, the electronic braking system acts as a mediator to translate driver steering input into vehicle directional control through selective application of brake force to individual wheels, ensuring continuous steering capability.
Solution Approach 2:
The system implements beforehand cushioning by pre-configuring a fallback steering mechanism using the existing electronic braking system. The controller is programmed to detect steer-by-wire failures and automatically switch to differential braking mode, providing a safety cushion that prevents complete loss of steering control.
2Reliability
If brake-to-steer system is implemented as fallback, then reliability is improved, but device complexity increases due to integration of braking and steering systems
Solution Approach 1:
The patent applies universality by enabling the electronic braking system to perform dual functions: its primary braking function and a secondary steering function. The same brake actuators and control electronics that manage vehicle deceleration are also utilized to generate differential brake forces for directional control, eliminating the need for separate backup steering hardware.
Solution Approach 2:
The system merges the steering and braking control functions by integrating them within a single controller architecture. The controller combines steering input signals with braking system commands, allowing the braking system to execute steering maneuvers through coordinated differential brake application, thereby reducing overall system complexity despite the multi-functional requirement.
3Ease of operation
If differential braking is used for steering, then ease of operation is improved during failure, but loss of time occurs during system switching
Solution Approach 1:
The system implements preliminary action by pre-mapping steering wheel inputs to corresponding differential brake forces before failure occurs. The controller maintains readiness to switch to brake-to-steer mode, and upon detection of steer-by-wire failure, the pre-established control algorithms immediately begin translating steering input into brake commands, minimizing switching time and maintaining operational continuity.
Data Source
AI summary
A number of illustrative variations may include a system and method of using vehicle brakes to steer a vehicle where steer-by-wire steering systems have failed. The system may include supplying varying brake pressure, as needed, to different vehicle wheels to steer the vehicle. The system may include supplying engine system commands to maintain vehicle speed or acceleration such that in the event of steering system failure, a vehicle may continue to operate safely without effecting driver input.