Nonlinear attitude control based on extended state observer for hypersonic vehicles

In this paper, a dynamic surface control strategy based on extended state observer is proposed for reentry attitude control of hypersonic vehicles with the presence of external disturbances and modeling uncertainties. Firstly, according to time scale, the system is divided into two parts, i.e. the inner subsystem and outer subsystem. Secondly, based on the hierarchical idea, two extended state observers are designed to estimate the modeling uncertainties in outer loop and external disturbance in inner loop respectively. Then, control laws of two subsystems are designed using the back-stepping technique. In order to improve the robustness, sliding model surface is used, and dynamic surface control technique is adopted to avoid explosion complexity caused by repeated derivative in back-stepping. Finally, the numerical simulation shows the power of this approach.