Fault reconstruction and state estimation with sliding mode observers for Lipschitz non-linear systems

This study considers the design of sliding mode observers for fault reconstruction and state estimations. In the sliding-mode observer design the switching terms are designed such that the faults are tracked and reconstructed from their respective sliding surfaces. As the fault reconstruction relies only on output estimation error, the reconstruction can be performed online with the state estimation. The stability condition for the reduced-order system is analysed and the feedback gain is designed such that the reduced-order system is stable. An application example to robotic manipulator is examined to demonstrate the effectiveness of the proposed method in reconstruction of unknown inputs/faults.