AN ACTUATOR FAULT TOLERANT APPROACH FOR UNDERWATER REMOTELY OPERATED VEHICLES

This paper presents a preliminary set of results on the design of Actuator Fault Detection Systems (AFDSs) for an underwater remotely operated vehicle (ROV) to prevent actuator faults and hence to reduce the risk of safety hazards. The approach consists of two phases. First a model-based approach is applied to the nonlinear model of the ROV. This solution permits to discover the redundancy of the system, and thus using it for fault detection purposes. Successively, by means of a Sliding Mode Control based approach, the fault is isolated and the control law is reconfigurated using the remaining working actuators. In both the phases the plant is assumed to be affected by “moderate” parametric variations. Moreover, it is supposed to undergo unknown faults, which cause the plant input components to be stuck at some uncertain but bounded time functions.