State of Charge Estimation of Metal Hydride Storage Tank Based on a Switched Observer

State of charge is a crucial metric for monitoring and controlling metal hydride storage tanks. However, designing model-based estimators for this system is complex due to the nonlinear, time-varying, and switched dynamics of the system. Additionally, this switched system presents operational modes where the system becomes unobservable. Considering these obstacles, this paper proposes a novel nonlinear switched observer for metal hydride storage tanks. Leveraging differential detectability and recent advances in contraction theory for switched systems, we establish sufficient conditions for the observer’s convergence, assuming synchronized switching between the observer and the plant. Furthermore, to ensure this synchronization, we propose an unknown system dynamics estimator to identify the current operating mode. The proposed approach is validated through a numerical simulation.