Dynamic-Command-Limiting-Based AOA Constraint Control of Hypersonic Flight Vehicle

In order to reduce the loss of maneuverability of hypersonic flight vehicle (HFV) when the angle of attack (AOA) is constrained, a dynamic protection control method based on command limiting is proposed in this article. First, a protection system is constructed based on the closed-loop dynamic approximation model, and the dynamic command bound is obtained online and fed back into the control system. Then, an adaptive AOA constraint controller based on command limiting is designed in the backstepping framework. Taking the advantage of bound estimation, the proposed control method only needs one adaptive law to deal with the lumped uncertainty. To avoid the violation of AOA limitation, the virtual command designed in the control system will be constrained and modified by using the bound obtained from the protection system, and a compensation signal is designed to attenuate the effect of command constraint. Rather than setting a conservative and constant value on the AOA command bound, the proposed constraint control scheme predicts the command bound dynamically and modifies the actual command online, which brings the advantage that the remaining AOA in a given interval can be fully utilized. Besides, the proposed controller does not have strict limitations on the initial state value. Even if the AOA exceeds the bound, the proposed algorithm remains effective. Finally, simulation results demonstrate the effectiveness of the proposed method.