Composite disturbance-observer-based control and terminal sliding mode control for complex models

A novel type of control scheme combined the distance-observer-based control (DOBC) with terminal sliding mode control is proposed for a class of continuous complex models subject to disturbances. The disturbances are supposed to include two parts. One in the input channel is generated by an exogenous system with uncertainty, which can represent the harmonic signals with modeling perturbations. The other is supposed to have the bounded H₂ norm. The disturbance observers based on regional pole placement and D-stability theory are presented, which can be designed separately from the controller design. By integrating DOBC with terminal sliding mode control laws, the disturbances can be rejected and the desired dynamic performances can be guaranteed for complex systems with known and unknown nonlinear dynamics, respectively. Simulations for a flight control system are given to demonstrate the effectiveness of the results and compare the proposed results with the previous schemes.