SBW Failure Steering Control Using Inner-Wheel Braking
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Solution Overview
Problem
Steer-by-wire (SBW) systems in vehicles lack a mechanism to ensure steering stability in the event of a failure without dualizing the system configuration, posing a safety risk, especially for autonomous vehicles.
Innovation Solution
A vehicle control apparatus and method that applies partial braking to turn-direction inner wheels and compensating driving force to the driving wheels using a controller, determining yaw moments based on desired and actual yaw rates to maintain steering stability, with additional controls to prevent wheel locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dualization of electric/electronic systems is applied to ensure safety against SBW system failure, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent extracts the essential safety function from the complex dualized SBW system by identifying that only partial braking force application to specific wheels is needed for failure compensation, rather than duplicating the entire steering system
Solution Approach 2:
The controller is designed to perform multiple functions: normal steering control under healthy conditions and failure compensation through partial braking and driving force adjustment when SBW system fails, eliminating the need for separate dedicated safety systems
2Stability of the object's composition
If partial braking is applied to turn-direction inner wheels to maintain steering stability during SBW failure, then steering stability is improved, but braking force loss occurs
Solution Approach 1:
Instead of applying braking force uniformly to all wheels or using full braking systems, the patent applies partial braking force selectively to specific turn-direction inner wheels, creating a localized solution that achieves steering stability while minimizing overall braking force consumption
Solution Approach 2:
The patent compensates for the braking force loss by applying driving force to the driving wheels, creating a counterbalancing effect that offsets the reduction in braking force while maintaining the desired steering stability
3Stability of the object's composition
If compensating driving force is applied to driving wheels to compensate for braking force reduction, then steering stability is maintained, but wheel locking may occur on low-friction roads
Solution Approach 1:
The patent dynamically adjusts the braking and driving forces based on real-time wheel slip detection, modifying the control forces in response to changing road conditions to prevent wheel locking while maintaining steering stability
Solution Approach 2:
The system incorporates wheel slip feedback to monitor the effect of applied forces and adjust the braking and driving force magnitudes accordingly, preventing excessive force application that would cause wheel locking on low-friction surfaces
Data Source
AI summary
A vehicle control apparatus includes a vehicle state sensor configured to detect state information of a vehicle, a braking force adjuster configured to adjust a braking force of the vehicle, a driving force adjuster configured to adjust a driving force of the vehicle, and a controller configured to control the braking force adjuster and the driving force adjuster, in which, when a steering system fails, the controller is configured to apply partial braking to the vehicle by providing a braking force to turn-direction inner wheels of the vehicle through the braking force adjuster according to a steering situation to allow the vehicle to turn left or right, and is configured to apply compensated driving to the vehicle by providing a compensating driving force corresponding to a reduction in braking force by the partial braking to driving wheels of the vehicle through the driving force adjuster.