Multiplicative fault estimation for a type of nonlinear uncertain system

This paper investigates the parameter estimation problem for a type of nonlinear system with multiplicative component faults and model uncertainties. Multiplicative faults are parameter changes within a process. Model uncertainties can be treated as an unknown input by appropriate transformation. An adaptive observer is proposed to estimate the multiplicative faults which are affected by system states and inputs. The component faults triggering oscillatory failures are considered. The proposed design is applied to a hydraulic rig model to verify its effectiveness.