Application of sliding mode observer for high dynamic near space UAV

Based on characters of high dynamic near space unmanned aerial vehicle (UAV) in re-entry mode, which has a large dynamic flight range and paramter uncertainty, a multiple-time-scale continuous sliding mode control (SMC) system is designed with Lyapunov methods. The outer loop is designed by using the conventional method, and the inner loop controller design, the moment control quantity is divided into two parts. One part is designed for stabilizing the known dynamic parts of the UAV and the other part, generated by sliding mode observer (SMO), is used to weaken and stabilize the disturbance items in order to improve robustness of control system. Requiring no more gain scheduling, this controller can adapt to the nonlinear, strong-coupled plant characteristics and large-scaled changes of the environment and it also has the ability to decrease the dependencies of the aerodynamics and structure parameters in different flight conditions. Validity, with high tracking accuracy, is demonstrated by the results of simulation.