Observer based thrusters fault diagnosis and management for the open-frame underwater robot

In order to improve the open-frame underwater robot to be a more reliable and maintainable one, a second order sliding mode observer has been established based on its dynamic model. The conditions of thrusters can be diagnosed through the residue of command quantity so that the fault can be found and dealt with on time. Despite the fact that the model of underwater robot possesses some uncertain factors, the fault of thrusters can still be identified accurately through the feed back from sensors. The observer is verified via the depth control experiments in the pond.