Switching LPV Control Method in Wide Flight Envelope for Hypersonic Vehicles

Hypersonic vehicles traverse a broad flight envelope with a wide parameter variation range and strong parameter uncertainties.Therefore it is important to improve the controller performance and robustness in a wide envelope.A new hysteresis switching linear parameter varying(LPV) control method using polytope theory and gap-metric is presented in this paper.The design envelope is firstly divided into several sub-regions in accordance with the time-varying parameters.A new LPV control method with the optimal gap-metric is proposed,and then a family of single LPV controllers are designed independently using the new method to improve the performance and robustness,each suitable for a specific sub-region.They are switched according to the time-varying parameter trajectories using the hysteresis switching strategy based on overlap regions to avoid chattering.The stability of the closed-loop switching system is also proved.Finally,the new switching LPV design approach is applied to a hypersonic vehicle.Simulation results show that this new method can improve the performance and enhance the robustness of the LPV controllers in a wide design envelope.The performance of command tracking and the robustness of the switching LPV control system are satisfactory.The stability of the system is also guaranteed.