Research On Dynamic Modeling And Attitude Control Of Hypersonic Vehicle With Compound Actuators

Hypersonic vehicle has attracted great attention for its strategic value all over theworld. A country will occupy the strategic height in the international high-techcompetition if he can master the hypersonic technology. It is also an importantguarantee of national security. The complicated and ever-changing flying environmentand large-scale maneuvers of the hypersonic vehicle, lead to the complex nonlinearityand strong coupling of the system. Besides, there is a lot of parameter uncertainty andunknown interference outside. Therefore, it is a challenging but meaningful researchsubject to design an advanced control system to make sure steady flight of thehypersonic vehicle.The paper takes the problem of low efficiency of aerodynamic fins for the reentryhypersonic vehicle into consideration, and proposes a compound control mode ofmoving mass control and aerodynamic control. Then the problems of dynamic modelingand attitude control for the hypersonic vehicle are researched under the compoundcontrol mode.Firstly, the principle of the configuration of moving masses is given. Based on this,the complete six DOF reentry mathematical model of the vehicle is established. Thenthe open loop characteristics are analyzed. Accordingly, the attitude motion equationsare rationally simplified and the control-oriented model is obtained.Secondly, the compound control allocation (CA) strategy is studied. A mixedoptimal control index with minimal CA error and control energy consumption isestablished at first. Then the CA problem is turned into a standard quadraticprogramming (QP) problem, and solved with fixed point method (FPM).Thirdly, according to the time-scale separation principle, the attitude system ofhypersonic vehicle is divided into two subsystems, a quick loop and a slow loop. Withthe dynamic inverse (DI) method, the two loops are linearized and decoupled separately,and the controllers are designed accordingly. After the attitude control system isdesigned, the simulation is conducted to validate the control performance.Finally，in order to reduce the control performance degrading caused by modeluncertainty, the adaptive neural network(NN) with weights updating on-line isintroduced on the basis of DI control. The NN can approximate the system uncertaintyand eliminate the inversion error in real time. Under the assumption of great aerodynamic uncertainty, the simulation is provided for the neural network-basedadaptive DI attitude control system.