Terminal sliding mode attitude controller design for a near-space hypersonic vehicle

A six-degree-of-freedom near-space hypersonic vehicle model is developed for control studies. This vehicle model has fast variability, is highly nonlinear, multivariable, and coupled, and includes parametric uncertainties. To improve the robustness of the attitude control system, a terminal sliding mode control is proposed and used for the design of attitude controller of a near-space hypersonic vehicle. Because the sliding surface is identical to zero, the approach process of SMC does not exist, which insures that the closed-loop control system is steady and has robustness along all system trajectories. In order to guarantee the performance of the control system, simulations are conducted for the responses of the commands of pitch angle, yaw angle, and rolling angle. The simulations demonstrate that the proposed attitude controller is robust with respect to the parametric uncertainties and atmospheric disturbances.