Adaptive Robust Control for Concurrent Combined Disturbances of Hypersonic Morphing Vehicle with Optimal Fuzzy Approximation

This paper designs a robust control scheme with optimal adaptive fuzzy approximation and variable structure nonlinear dynamic inversion (VSNDI) to solve the problems of multi-mode variable structure flight and unknown combined concurrent disturbances of hypersonic morphing vehicle (HMV). First, an VSNDI controller is proposed in the affine HMV. Then fuzzy approximation estimates the nonlinear parameters, where the iterative optimization strategy minimizes the estimation errors and makes the nonlinear parameters accurate enough to ensure the VSNDI’s effectiveness. Aiming at the combination disturbances formed by the approximation errors and external multi-disturbances, the variable structure adaptive law in each channel is proposed to adjust the amplitudes of the fuzzy free parameter weights, thence combining the independently designed fuzzy robust compensator to real-time suppress disturbances. The variable structure residual adaptive laws for cross-channel nonlinear matrices in VSNDI solve the coupling problem of the combined concurrent disturbances caused by sea-skimming flight. Finally, variable structure and fuzzy control scheme enable HMV to achieve accurate tracking under multi-mode and complex disturbances. The system stability is proved by Lyapunov theory, and the effectiveness of the method is proved by simulation experiment.