Multi-model Switching Control Of Hypersonic Vehicle With Variable-Geometry Scramjet Inlet

AIR-BREATHING HYPERSONIC VEHICLE(AHV)may offer a reliable and more cost-efficient way to access space by reducing flight time.In practice,hypersonic aircraft always fly within a large flight condition range.However,for the AHV with fixed geometry-geometry scramjet inlet,once it is running at a low Mach,the shockwave would deviate from the scramjet lip,this will lead to the scramjet engine could not get sufficient stream,so that thrust will be generated insufficiently.In order to solve the above issue,a widely used variable geometry inlet scheme —translating cowl,was proposed by the ONERA.By moving the movable inlet lip along the flow direction,the internal contraction ratio could be enlarged,and the propulsion efficiency could be improved.This variable geometry inlet scheme is easy to operate,which only need to translate the movable cowl to ensure that the shockwave can project right on the inlet lip.Thus,it provides a feasible idea for us to study the AHV control combine with the variable geometry scramjet inlet.However,the variable-geometry scramjet inlet can cause the uncertainties of model structures and parameters in the meanwhile.So,it's impossible to describe the AHV by a single mathematical model.For this reason,we decide to adopt the multi-model switching control(MMSC)method to design the controller of the AHV with variable-geometry scramjet inlet to tackle the strong nonlinearity and interaction characteristics.According to the working conditions,we build several nonlinear aerodynamic models with different length of the movable lip.For each model,a specific neural network controller has been adopted.By constructing the common Lyapunov function,it is proved that all signals of the closed-looped system are uniformly ultimately bounded by the continuous controller.The global controller of the system is obtained by fuzzy-weighting the local controllers to realize the soft-switching.Numerical simulations are presented to verify the feasibility of the proposed control approach.