Research Of Missile Guidance And Control System Based On Active Anti-disturbance Control Theory

Missile is a kind of guidance weapon with two important components,which are guidance system and stability control system.The guidance system measures the relevant distance and movement information between missile and target,or the difference between the actual route and the designed route of the missile,and develops the guidance command according to the guidance law.The stability control system maintains the stability of the missile during the flight,and adjust the missile attitude according to the guidance command.The design of the missile guidance and stability system is influenced by many factors,such as the parameter perturbation,model uncertainty,external disturbance and so on.These factors degrade the guidance performance of the missile severely.In order to improve the hit accuracy,enhancing the anti-disturbance performance becomes an important research objective of the missile guidance and stability system.Since the active anti-disturbance technique can suppress disturbances rapidly,it has been widely recognized by the academic world and has been applied in the missile system design successfully.The application of the active anti-disturbance technique in the missile guidance and stability control system under different kinds of disturbances is studied in this thesis.The main contents are as follows: the design of an adaptive missile autopilot with the consideration of time-varying parameters;the study of a3 D missile guidance law based on the nonlinear disturbance observer with the consideration of autopilot dynamics;the study of a 3D missile guidance law based on the generalized proportional integral disturbance observer with the consideration of autopilot dynamics;the study of a composite sub-optimal 3D guidance law.The main research contents are as follows:(1)Considering that the parameters of the missile stability control system are time-varying,a composite autopilot with an adaptive disturbance observer is designed.First,the nonlinear couplings of the autopilot model are regarded as a part of the lumped disturbance,and the three channels of the autopilot are separated in this way.Next,a linear disturbance observer is designed to estimate the lumped disturbance.Then,the nominal model of the linear disturbance observer is improved based on the one-dimensional interpolation algorithm,so that it can change along with the flight condition.In the end,a state feedback controller is designed for the linear part of the autopilot model,the lumped disturbance is compensated by feed-forward control based on the estimation,and a composite autopilot is obtained.The simulation results show that the proposed autopilot improves the estimation performance of the linear disturbance observer under time-varying parameters,and enhances the robustness of the missile stability control system.(2)With the consideration of the first-order autopilot dynamics,an anti-disturbance composite 3D guidance law is developed for the missile intercepting targets in 3D space.First,a first-order inertial element is used to simulate the autopilot dynamics.Next,the unknown target acceleration are regarded as the disturbance,and a nonlinear disturbance observer is designed to estimate the disturbance.Finally,the estimation of the target acceleration is included in the virtual control law design based on the backstepping control method,and the mismatched disturbance is fed forward and compensated in this way.The simulation results show that the proposed nonlinear disturbance observer can estimate the target accelerations of the constant/slow timevarying type,and the corresponding composite 3D guidance law can enhance the robustness of the missile guidance system.(3)As the nonlinear disturbance observer can only be used to estimate constant disturbances or slow time-varying disturbances,the above composite 3D guidance is improved for a better engineering practicability in this thesis.Considering that the target acceleration can not be measured precisely,a composite 3D guidance law is developed based on the generalized proportional integral disturbance observer for the missile guidance model with the first-order autopilot dynamics.First,the autopilot dynamics simulated by the first-order inertial element are introduced into the 3D missile-target interception model.Next,the unknown target acceleration is regarded as the disturbance,which is mismatched.Then,the generalized proportional integral disturbance observer is designed to estimate the unknown target acceleration and its derivatives.Finally,the estimation of the target acceleration is involved in the virtual control law based on the backstepping control method,and the feedforward compensation is realized in this way.The composite 3D guidance laws based on the generalized proportional integral disturbance observer and the nonlinear disturbance observer are compared in the simulation part.The simulation results demonstrate that generalized proportional integral disturbance observer can estimate the disturbance expressed by a polynomial,and the corresponding composite 3D guidance law has a wider engineering application range.(4)An anti-disturbance 3D sub-optimal guidance law is proposed for the optimal problem of the missile3 D guidance law.First,a 3D sub-optimal guidance law is proposed based on the ?-D method for the 3D missile-guidance interception model without considering the target maneuvering.Then,the target acceleration is seemed as a disturbance,and a nonlinear disturbance observer is designed to obtain the estimation.In the end,the influence of the target acceleration is compensated by the feed-forward control.The effect of the nonlinear disturbance observer for the 3D sub-optimal guidance law is studied in the simulation part.The simulation results demonstrates that the proposed composite 3D sub-optimal guidance law raises the hit accuracy of the missile.