UBC Theses and Dissertations
Implementation of a health monitoring system within a fault tolerant steer-by-wire system Li, Mo
The objective of this thesis is to examine the improvement of the design and implementation of a fault tolerant Steer-by-Wire system. This application integrates the methods of multi-level redundancy developed in previous work with a tool set for monitoring the health of the computer controlled system. It allows the system to tolerate faults at all levels of its organization. The health monitoring system adopted is based on a simplified representation of the dynamic model of the Steer-by-Wire application. By comparing the output of a system model to the actual output achieved by the application, it provides three measures of component health, all of which indicate errors based on the performance of a system state relative to a base model. The analytical redundancy provided by the health monitoring system may be used to either reduce overall system cost through replacement of a physical sensor, or as an additional sensor to allow continued voting after the first failure of a physical sensor thus avoiding significant system degradation. The health monitoring system has been implemented on a prototype of a three-wheeled vehicle. The vehicle has two "independent" steering systems: the first resembles a conventional power assist, the second a Steer-by-Wire configuration.
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