Modeling and control of hypersonic vehicle dynamic under centroid shift

Due to the huge flight scale and the fast speed of hypersonic vehicle, the system must be of strong nonlinearity, coupling, and fast time variability, which give rise to the huge challenge for the design of controller. The good control performance must be based on the elaborately designed controller, which is established in the carefully designed center of mass. Once the center of mass moves unexpectedly, it is bound to affect the ability of existing flight controller to maintain the stability of hypersonic vehicle, resulting in serious consequences, even loss of control. Based on Newton's laws and Varignon's theory, a mathematical model for hypersonic vehicle with centroid shift is built up to research the influence of centroid on the motion of hypersonic vehicle. The zero-input response tests are conducted from the different aircraft body axes of the coordinate. Simulation results show that such influence is coupling, abrupt, irregular, and time-variant. In order to inhibit the bad influence of unexpected centroid shift, terminal sliding mode controller combined with radial basis function neural networks and just terminal sliding mode controller alone are adopted to handle such problems in view of robust control itself and auxiliary compensation. Simulation results show that such influence can be inhibited and compensated in a certain region, and the further research is still needed.