Nonlinear sliding mode observers for fault reconstruction and state estimations

In this paper, we shall examine the design of sliding mode observers for Lipschitz nonlinear systems for state and faults/unknown input estimations. The robust terms or the switching terms are designed such that the faults are tracked by their robust terms and so can be reconstructed from the sliding mode. The stability condition for the reduced order system is analyzed 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.