Application of a robust nonlinear fault detection observer to a hydraulic system

This paper proposes a method for fault detection of a nonlinear system by means of a nonlinear observer. The observer is designed such that the error dynamics are independent of state, input, output and unknown disturbances. The conditions necessary for the observer to exist and be robust with respect to the unknown input are given. The method is applied to a hydraulic test rig and a simulation study is carried out. Results from the implementation of the observer are included. This observer is used to form an intelligent monitoring system to enable the reliability and maintainability of a system to be improved.