Entry trajectory tracking of RLV based on fuzzy variable structure control

To reduce the dependence of trajectory tracking of reusable launch vehicle (RLV) on the aerodynamic parameters and initial conditions, and improve the robustness of traditional control method, a new entry trajectory tracking method based on the fuzzy variable structure is proposed from the perspective of longitudinal tracking guidance. Also, a method of on-line planning the point of the bank angle reversal is designed in the aspect of lateral trajectory control. The simulation results show that the longitudinal tracking control method which is based on the fuzzy variable structure can track the designed trajectory perfectly and stably, and has strong robustness in the condition of big initial state error and aerodynamic coefficient error. The online searching of the bank angle reversal point can be realized by using the proposed lateral guidance method, which can also improve the lateral guidance accuracy effectively.