Brake-Based Steering Backup for Autonomous Vehicle Failures
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Solution Overview
Problem
In autonomous motor vehicles, drivers may lose control over steering and braking when these systems fail, posing a safety risk, particularly since fully autonomous vehicles lack the ability for timely driver intervention, and redundant solutions like doubling actuators are weight- and cost-intensive.
Innovation Solution
The system compensates for steering failures by using coordinated acceleration and deceleration of individual wheel drives or brakes based on current driving parameters like vehicle speed, yaw rate, and steering angles to adjust the vehicle's direction, leveraging existing vehicle dynamics control systems like ESC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant steering actuators are implemented to ensure steering safety in autonomous vehicles, then steering reliability is improved, but vehicle weight and cost increase significantly
Solution Approach 1:
The existing braking system, originally designed solely for deceleration and stopping, is made multi-functional by enabling it to perform steering assistance functions. The braking control unit is modified to calculate and execute asymmetric braking forces on individual wheels based on steering commands, allowing the same hardware to serve both braking and steering purposes, thereby providing redundancy without adding weight
Solution Approach 2:
The braking system serves itself by using its own actuators and control capabilities to perform the steering function. When steering actuator failure is detected, the braking system autonomously takes over steering control by applying differential braking forces to the wheels, eliminating the need for separate redundant steering actuators and reducing overall system complexity
2Reliability
If redundant steering actuators are implemented to ensure steering safety in autonomous vehicles, then steering reliability is improved, but manufacturing cost increases significantly
Solution Approach 1:
The braking control unit is enhanced with additional control logic to enable it to perform steering functions. By using the existing braking hardware for dual purposes (braking and steering), the patent eliminates the need to manufacture and install separate redundant steering actuators, significantly reducing component costs and assembly complexity while maintaining steering safety
Solution Approach 2:
The steering control function and braking control function are merged into a unified control approach. The braking control unit integrates both braking commands and steering commands, processing them through a single control system that can execute both functions using the same physical infrastructure, thereby reducing overall system cost
3Extent of automation
If the driver relinquishes complete control to the autonomous vehicle, then automation level is improved, but safety response capability deteriorates when steering failures occur
Solution Approach 1:
The braking system acts as an intermediary backup mechanism between the autonomous driving system and the vehicle's directional control. When the primary steering actuator fails, the braking system serves as a mediator to restore steering capability by applying asymmetric forces to the wheels, ensuring that even fully autonomous vehicles maintain safety response capability without requiring constant driver intervention
Data Source
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AI summary
A control system and method designed and intended for use in a motor vehicle, based on environmental data obtained from one or more environmental sensors assigned to the motor vehicle, to effect at least semi-autonomous driving operation of the motor vehicle by means of assigned actuators, and wherein the control system is designed and intended to detect a failure of a conventional steering system of the motor vehicle, and to effect a change in direction of the vehicle corresponding to a target steering angle from current driving parameters by means of coordinated acceleration and/or deceleration interventions of individual wheel drives or wheel brakes of the vehicle.