Steering System Degradation Evaluation for Fault-Tolerant Power Demand
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Solution Overview
Problem
Existing steering systems in road vehicles, particularly in electromechanical and autonomous steer-by-wire systems, lack comprehensive information on degradation or malfunction of individual components, hindering fault-tolerant operation and necessitating improved methods to determine the actual operation state.
Innovation Solution
A method to control steering systems by determining overall degradation levels through evaluating individual component levels, defining operation modes based on performance limits, and adjusting performance limits to meet power demands, with feedback to the driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If comprehensive degradation monitoring of individual components is implemented, then fault tolerance and safety are improved, but device complexity and information processing requirements increase
Solution Approach 1:
The steering system is divided into multiple individual components and sub-systems, each with its own degradation monitoring. The evaluator segments the overall degradation level into individual component degradation levels, allowing targeted monitoring without requiring complete system overhaul.
Solution Approach 2:
An evaluator component acts as an intermediary between individual component sensors and the controller. The evaluator collects single individual degradation levels, determines overall degradation level, and provides information to the controller, simplifying the information processing architecture.
2Adaptability or versatility
If multiple degraded operation modes are defined with different performance limits, then adaptability to degradation states is improved, but control system complexity increases
Solution Approach 1:
The control system dynamically adapts performance limits based on the determined overall degradation level. The controller modifies performance limits for degraded operation modes according to the actual degradation state, allowing flexible response to varying degradation conditions without requiring a completely different control architecture.
Solution Approach 2:
Performance limits are adjusted as parameters based on the degradation level. The controller modifies power demand calculations and performance thresholds according to the evaluated degradation state, enabling adaptive operation across different degradation scenarios.
3Reliability
If real-time degradation evaluation is performed to determine operation state, then safety and fault detection are improved, but processing time and computational load increase
Solution Approach 1:
The evaluator continuously monitors and evaluates degradation levels in advance, maintaining readiness to determine the overall degradation level when needed. Degradation information is collected and prepared beforehand, allowing rapid determination of operation state when degradation occurs or changes.
Solution Approach 2:
The system implements continuous feedback loops where degradation information flows from sensors to evaluator and then to controller. This closed-loop feedback enables real-time degradation evaluation and automatic adjustment of operation modes without requiring complex batch processing.
Data Source
AI summary
A method to control a steering system or a sub-system of a road vehicle including a controller to operate in a normal mode with full steering functionality and no quality problems and at least two degraded operation modes with degraded operation of the steering system, the controller including an evaluator including an allocation between degradation levels of the steering system or the sub-system and operation modes, and the method includes determining an overall degradation level for the steering system or the sub-system by collecting single individual degradation levels of the steering system or the sub-system in the evaluator and determining an overall degradation level as a level with a highest degradation of the single individual degradation levels which in a corresponding operation mode provides enough performance of the steering system for an expected maximum power request.