A Global Sliding Mode Based Tracking Guidance Law with Fixed-Time Convergence for Reentry Vehicle

The model of reentry vehicle is strongly coupling, nonlinear, fast time-varying and uncertain. And its flight environment is complex and highly variable. To eliminate these bad effects in the design of control and guidance, a global sliding mode based tracking guidance law with fixed-time convergence is investigated in this paper. Firstly, the three-degree-of-freedom reentry guidance model is proposed. And we take the longitude as the dependent variable of the interpolation instead of the time in the standard reference trajectory. So the trajectory of the three variables is transformed into the tracking of the height and latitude. Then, a global sliding mode based tracking guidance law with fixed-time convergence is designed for the trajectory tracking matters. Finally, some simulations are shown to illustrate the effectiveness of the trajectory-tracking guidance algorithm.