Sliding mode attitude control with input constraints for near space vehicles in reentry phase

A stable adaptive auxiliary system is designed according to the input constraints problem for the near space vehicle (NSV) in reentry phase, which can realize the compensation for control saturation. The NSV flies with the large angle of attack during reentry, and the compound control mode of aero-surfaces and reaction control system is adopted. Then, the reentry attitude control system of the NSV is designed using the second-order terminal sliding mode control law combined with the saturation compensation. Finally, the sliding mode disturbance observer is employed to estimate the aerodynamic parameter uncertainty and external disturbance. Meanwhile, its compensation adaptive law is deduced. The simulation results show the effectiveness and robustness of this scheme.