Robust exact differentiator based full-order nonsingular terminal sliding mode for re-entry attitude control

Considering the reentry vehicle with strong inherent coupling and highly nonlinear, a full-order nonlinear terminal sliding mode control scheme was proposed based on terminal sliding mode and robust exact differentiator (RED). Firstly, a novel full-order nonsingular terminal sliding mode control function was designed so that the derivatives of terms with fractional powers could not appear in the controller. Thus the control singularities could be avoided. Moreover, the tracking errors could be converged to 0 in finite time. Then, to obtain the derivatives of the angular velocity signal in the sliding mode manifold, a super-twisting algorithm (STA) was applied as robust exact differentiator. The interfering noise magnified with the common differentiator could be avoided because of the robustness of the RED. Furthermore, the filter and boundary layer technique were combined to alleviate chattering of the sliding mode controller. Finally, simulations were provided for the reentry vehicle with uncertain parameters and external disturbances to illustrate the effectiveness and robustness of the attitude control system.