Redundant Steering Motor Switching for Autonomous Vehicle Fault Detection
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Solution Overview
Problem
Autonomous vehicles face challenges in safely navigating with redundant steering systems, as existing technologies struggle to monitor and manage the performance and offset of steering motors, potentially leading to faulty operations and unintended driver interventions.
Innovation Solution
A method that involves sending control commands to steering motors based on vehicle speed, yaw rate, and pre-determined offsets to determine an expected range of steering angles, with secondary motors activating if the primary motor's position or torque deviates, ensuring safe navigation and preventing false positives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a redundant steering system with multiple motors is used, then reliability is improved, but device complexity increases
Solution Approach 1:
The steering system is divided into multiple independent motor units (first motor and second motor), each capable of independently controlling the steering wheel. This segmentation allows the system to maintain reliability through redundancy while managing complexity by treating each motor as a separate controllable module with its own control algorithm.
Solution Approach 2:
The system dynamically changes operational parameters by switching between different motor units based on real-time performance monitoring. When the primary motor's steering angle deviates from the expected range (determined by vehicle speed and yaw rate), the system transitions to using the secondary motor, thereby adapting to changing system conditions and maintaining reliability.
2Reliability
If steering motor performance monitoring is implemented, then reliability is improved, but measurement precision requirements increase
Solution Approach 1:
The system implements continuous feedback monitoring of the steering motor's actual performance by comparing the measured steering angle against the expected steering angle range (calculated from vehicle speed and yaw rate). This feedback mechanism enables reliable fault detection without requiring extremely high measurement precision, as it monitors deviations from expected operational parameters rather than demanding absolute precision.
Solution Approach 2:
The system pre-calculates the expected steering angle range based on vehicle speed and yaw rate before actual steering operations occur. This preliminary action establishes a reference framework that simplifies real-time monitoring, allowing the system to detect faults by comparing actual measurements against pre-established expectations rather than requiring continuous high-precision measurements.
3Reliability
If expected steering angle range is calculated based on vehicle speed and yaw rate, then reliability is improved, but loss of time in calculation increases
Solution Approach 1:
The system calculates an expected steering angle RANGE rather than a single precise value, using partial information (vehicle speed and yaw rate) to establish bounds within which the steering angle should fall. This partial action approach provides sufficient fault detection capability without requiring complete real-time calculation of optimal steering angles, thereby reducing computational time while maintaining reliability.
Data Source
AI summary
Techniques are described for managing redundant steering system for a vehicle. A method includes sending a first control command that instructs a first motor coupled to a steering wheel in a steering system to steer a vehicle, receiving, after sending the first control command, a speed of the vehicle, a yaw rate of the vehicle, and a steering position of the steering wheel, determining, based at least on the speed and the yaw rate, an expected range of steering angles that describes values within which the first motor is expected to steer the vehicle based on the first control command, and upon determining that the steering position of a steering wheel is outside the expected range of steering angles, sending a second control command that instructs a second motor coupled to the steering wheel in the steering system to steer the vehicle.