Sliding mode state observer for 2-DOF twin rotor MIMO system

This paper presents a sliding mode state observer for the 2-DOF twin rotor MIMO (multi-input-multi-output) system which belongs to a class of inherently nonlinear systems. Design parameters are selected such that on the defined switching surface, asymptotically stable sliding mode is always generated. Robust sliding and global asymptotic stability conditions are derived by using Lyapunov method. The unknown nonlinearities are estimated and the state estimation errors tend to zero asymptotically.