Gain Scheduling Control Of Systems With Input Constraint And Its Applications To Near Space Vehicle

Saturation nonlinearity exists in every practical control system. However, the actuator saturation nonlinearity on the physical actuator and the influence of saturation nonlinearity for the stability of the closed-loop system are not taken into consideration during the controller design in many modern control theory. Then the designed controller cannot be applied in the engineering practice. The consideration of the actuator saturation nonlinearity during the controller design may lead the suitable controller more difficult to design. So the system with input constraint has important research value. This thesis settles the controller design problem for systems with input constraint by solving the parametric Riccati equation. The effectiveness of the proposed approaches are validated by the controller design for near space vehicle. The following works are mainly considered.The controller design methods based on the parametric Lyapunov equation are proposed for switched systems with input constraint and uncertain switched systems. Each subsystem of switched systems with input constraint have different equilibrium points, the discrete gain scheduling controller is designed for switched systems with input constraint.The proposed gain scheduled controller improves the dynamic performance of the closedloop systems by increasing the design parameter representing the convergence rate of the closed-loop system. The robust discrete scheduling controller is proposed for uncertain switched systems with input constraint. The switching controller is used to guarantee that the actuator saturation not to occur, and the closed-loop system is stable. A condition for the closed-loop system to be robust stability can be obtained. The parametric Lyapunov method can deal with unstable plant, then the proposed approaches are extended to exponentially unstable linear systems. The approach is verified to be valid.The problem of robust control of systems with input constraint is studied. A robust continuous static gain scheduling state feedback controller is given to solve the problem of robust stabilization of systems with input constraint and uncertainties. And the stability problem of the system when the disturbance not equal and equal to zero are both studied.A robust continuous static gain scheduling output feedback controller is proposed to solve the problem of robust stabilization of systems with bounded input and input uncertainties.By scheduling the design parameters, the convergence rates of the closed-loop can be improved, and the approach is verified to be valid.The problem of controller design for systems with asymmetric input constraint is considered. The relation of the asymmetric saturation function and symmetric saturation function is given by using the simple variable substitution, and the invariant sets and stabilization problem of systems with asymmetric input constraint are investigated. For linear systems with asymmetric input constraint, by using the symmetric saturation nonlinearity,the discrete gain scheduling state feedback control approach is proposed. This method is given to estimate the maximal invariant set for systems with asymmetric input constraint.By increasing the parameter, the convergence rates of the closed-loop system can be improved. The resulting closed-loop system is exponentially stable. The proposed approach is applied to numerical example and BTT missile model. Numerical simulations show the validity of the proposed approach.The last part utilizes the results in Chapter 2, Chapter 3 and Chapter 4 to design controller for near space hypersonic vehicle with input constraint. The problem of controller design for switched system with asymmetric input constraint are designed by the approach developed in Chapter 2 and Chapter 4. The designed controllers are applied to the time-invariant system, switched system, time-varying system and nonlinear system.The proposed approaches can guarantee that control signal satisfies the actuator saturation constraint.