Composite terminal sliding mode control for class of high-order nonlinear dynamic system

A composite control method is proposed based on adaptive terminal sliding mode control and disturbance observer theory for a class of high-order nonlinear dynamic systems. In this control method, the disturbance observer is introduced to estimate system disturbance and the estimated value is used to compensate sliding mode controller's outputs to restrain the unknown uncertainty. For controller output chattering case, an adaptive law based on disturbance observer is designed. Under the adaptive law, the controller's switching gain can be adjusted automatically, which can reduce the high frequency chattering of outputs. The Lyapunov theory is applied to prove the stability of the control method. Finally, the simulation results of an example show the feasibility and effectiveness of the proposed approach.