Variable Structure State and Input Observation

The robust observation of dyamical systems maybe regarded as a problem of simultaneous state and input estimation. Under certain structural (matching) conditions this problem can be solved by the design of switched observers. Recent results on globally stable, switched observers are restricted to systems that have disturbance-to-output dynamics of relative degree one. In this paper a switched observer is proposed for systems with disturbance-to-output dynamics of relative degree two. The result is applied for the state and input observation of a two-link robot.