Research on multi-model of hypersonic vehicle based on bifurcation theory

The bifurcation theory was employed to divide the multi-model of hypersonic vehicle. The eigenvalue topologies of nonlinear dynamics of hypersonic vehicle were obtained through applying the continuation method, and the relation between the eigenvalue and dynamics of sub-model was established. Based on the variation of dynamic characteristics, the multi-models were successfully divided. Firstly, the relation between eigenvalue and dynamics of sub-model was established, and the topologies of eigenvalue of longitudinal model (short period mode) was being computed and the relation between eigenvalue and sub-model dynamics was given, after that the three sub-models for longitudinal model were obtained; Correspondingly, for the lateral dynamic model, the topologies of eigenvalue corresponding to Dutch roll mode and roll subsistence mode were computed and the lateral model was divided into 6 sub-models finally. Lastly, the eigenvalue topologies for 5 order coupled model was computed and coupled dynamic model was divided into 4 sub-models. The results above can provide the important information for strategies of control and switch of the sub-models as well as controller design for hypersonic vehicle.