A Structure-graph Approach to Diagnosis and Control Reconfiguration Design - exemplified by Station-keeping Control

This paper addresses the design process of diagnosis and fault-tolerant control when a system should operate despite multiple failures in sensors or actuators. Graph-theory based analysis of system's structure is demonstrated to be a unique design methodology that can cope with the diagnosis design for systems of high complexity, and also analyse the cases of cascaded or multiple faults. The paper demonstrates the design method on a ship with three actuators: two shafts with CP propellers and a bow thruster, and navigation instruments: global position sensors (GPS), inertial navigation units and conventional gyros to provide ship motion information. A salient feature of the design method is shown to be the ability to analyse cases where one or more faults have occurred and rapidly determine where in the faulty system reconfigurability, diagnosability and controllability are retained.