Compensation-based Robust Decoupling Control Of Flight Vehicles

In the thesis, we consider the problem of coupling and uncertainty in attitude control system. Firstly, we simplify the attitude control model and derive a nominal model. The nominal model is decoupled with backstepping design method. Then, we design the control law for the nominal model. Besides, the exten ded high-gain observer is designed for the attitude control model. The observer can estimate the uncertainty of the attitude control system and the uncertainty should be compensated to this system. The state value can be replaced by the observed value, because the performance of state feedback can be recovered by output feedback when the gain is really high. Then we finish the control law design of flight vehicles and perform the simulation verification. The main content of this thesis are as follows:Firstly, some common coordinate systems and the transformati onal relations of them are given. Then, we deduce and establish three-dimensional model of missile’s attitude control through knowledge of missile’s force and moment analysis, dynamics equation and kinematic equations. The model includes nominal model part and uncertainty part. So, we finish the preparations for the design of nominal model’s control law and extended observer.Secondly, we propose decoupling control method base d on backstepping for the multivariable attitude control system with strong coupling. Then we design the control law for the nominal model of attitude control model. The original complex system is separated to several subsystems. We design Lyapunov function for each subsystem to ensure the stability of the system and deduce medial virtual control to obtain the real control law of nominal model. So, we realize the decoupling of system and finish the design of nominal model’s control law.Thirdly, considering the uncertainty in the model, we design extended high-gain observer for the attitude control system in knowledge of high-gain observer. Meanwhile, the uncertainty should be extended. Then we simulate and compare the performance of observers in different parameters. Besides, we analyze the peak phenomenon of observers and propose the solution for it.Finally, we estimate the coupling and uncertainty part of system with extended observer, and uncertainty should be compensated to this system as well. The state feedback control is replaced by output feedback control. Besides, we use saturation control to deal with peak phenomenon. So we finish the decoupling control of system and make the system has high convergence speed and convergence accuracy. Then, we simulate for the flight vehicle’s control law and compare the decoupling and tracking performance of nominal closed-loop system to closed-loop system with high-gain observer to validate the control performance of the control law.