Body-flap attitude control method for lifting re-entry vehicle

An attitude output tracking control method is proposed for a lifting re-entry vehicle with a non-minimum phase property. Such problem is caused by body flaps which are the only actuators to be used for controlling three-channel. By using local differential homeomorphism, the attitude input-output model is transformed into normal form, and internal dynamics are obtained. A criterion of non-minimum phase is developed by analyzing the internal dynamics' stability, and this criterion is used to predict the non-minimum phase phenomena when aileron reversal exists. To solve this problem, the normal form is decomposed into a minimum phase subsystem (longitudinal channel) and a non-minimum phase subsystem (lateral-directional channel). And then, dynamics inversion is used to design the state-feedback controllers for these two subsystems. Moreover, a nonlinear auxiliary control input is introduced to stabilize the overall attitude control loop by both Lyapunov function and a minimum-norm control strategy. Simulation results demonstrate that in the case where body flap actuators are employed for attitude control, the control commands can be tracked and internal dynamics can be stabilized by the proposed method.