Actuator Fault Estimation for Distributed Interconnected Lipschitz Nonlinear Systems with Direct Feedthrough Inputs

Distributed interconnected systems are complex dynamic systems where every single subsystem has an impact on other subsystems. Actuators are key components in interconnected dynamic systems, which are prone to faults due to age and unexpected conditions. Therefore, there is motivation to develop an effective diagnosis algorithm for distributed interconnected systems, which is a starting point for predictive maintenance. In this study, an actuator fault estimation approach is proposed for a class of nonlinear interconnected systems with direct feedthrough inputs. Specifically, the original interconnected system is transformed into an augmented system by setting an extended state vector composed of an original state vector and actuator fault vector. An additional control term is used to eliminate the impact from unknown disturbances on the estimator error dynamics. Regional pole constraints are considered in the design of the distributed robust observer so that the poles are placed into a desired stable region. The observer gains are obtained by solving simultaneous linear matrix inequalities. Finally, the effectiveness of the proposed method is demonstrated by simulation studies, and a comparison is also provided.