A new result of terminal sliding mode finite-time state and fault estimation for a class of descriptor switched systems

The paper investigates the finite-time state and fault estimation problem for continuous-time descriptor switched systems. A more representative faulty plant is considered, where unknown additive sensor and process faults, the Lipschitzian disturbance in state dynamics, and the external composite disturbance in the measured output exist simultaneously. Compared to some existing actuator models, a more representative actuator fault model is given, where some bounded conditions of the degradation and the additive fault are canceled. The actuator empirical efficiency is also introduced to estimate the time-varying actuator degradation. An important highlight is the extension of the Lyapunov terminal sliding mode (TSM) condition of finite-time stability into descriptor switched systems, where the method of average dwell time (ADT) is considered. A novel adaptive sliding mode observer is developed by constructing an augmented system model, and the relevant rank conditions are proved. To validate the effectiveness of the proposed observer, a descriptor switched circuit system is simulated under different control inputs and various actuator fault models. It can be seen that the TSM finite-time state and fault observer acquires the fast and accurate estimation of the targeted vector.