Contribution to the Fault Tolerance for Hybrid Control Systems with Multiple Faults

Abstract

Many diagnosis approaches are based in the assumption of single faults. This assumption may result to erroneous diagnosis statement in case where multiple faults occurs. Thereby multiple fault diagnosis is a challenging task especially in the control of large scale complex systems that can be viewed as hybrid systems. This owed to the fact that multiple faults are hard to detect because there consequences can mask or compensate to each other. The goal is to detect multiple faults as early as possible and provide a timely warning. A key issue is to prevent local faults to be developed into system failures that may cause safety hazards, stop temporarily the production and possible detrimental environment impact. This can be achieved by fault tolerant witch means that despites the faults occurrences the system is able to recover its original task with the same or degraded performance. Fault tolerance can be considered that it is constituted by two basic tasks, fault diagnosis and control redesign. In our work we addressed mainly to the first task introducing a method for multiple fault diagnosis in hybrid systems, while we propose a framework for fault tolerant hybrid control systems, which allows retaining acceptable performance under systems faults. The method is tested via a simple application to an electric power transmission system presented in our previous work.