Application of adaptive second-order dynamic terminal sliding mode control to near space vehicle

In order to overcome chattering problem,a second-order dynamic terminal sliding mode control scheme was proposed. The terminal sliding mode control speeds up the convergence of tracking error and the second-order dynamic sliding mode control obtains continuous controller in time domain by embedding discontinuous functions into the first-order differential of controller and making the sliding surface and its derivatives equal to zero. Thereafter,a nonlinear disturbance observer was used to approximate compound disturbance. Adaptive compensation term was added to the controller,relaxing the prerequisite of nonlinear disturbance observer. The system was proved stable based on Lyapunov theorem. Finally,the simulation applied to near space vehicle has demonstrated the superiority and effectiveness of the control scheme.