A Robust Approach For Missile Attitude Control Based On Disturbance Estimation And Compensation

Because of high speed,strong penetration ability,flexible way of use and high combat effectiveness,the short-range tactical ballistic missile has been widely used in modern high-tech local wars.As the offense-defense confrontation between missile technology and anti-missile technology becomes more and more intensified,developing missiles with full-range controllability,high agility and multiple trajectories becomes an inevitable trend.As a result,the corresponding flight dynamics exhibits high nonlinearity,strong coupling,and large parameter variations and suffer from various uncertainties and disturbances,which brings great challenges to missile attitude control system design.To this end,this dissertation mainly focus on the attitude control system design and presents a robust design approach based on disturbance estimation and compensation.The main research contents and results are as follows:Since classical robust control method cannot achieve a satisfactory tradeoff between robust stability and performance when the system undergoes great uncertainties and disturbances,to tackle this problem,an improved robust approach based on disturbance estimation and compensation is proposed.All the model uncertainties,disturbances and nonlinear items are regarded as a lumped disturbance imposed on the input channel and a linear generalized extended state observer is designed to estimate the lumped disturbance and simultaneously compensate it in real time.In doing so,the plant model uncertainty can be reduced within an appropriate range for robust control design.Then effective robust control approaches can be utilized to design controllers that achieve the desired closed-loop specifications such as tracking performance,control effort limitation and robust stability.Also,the closed-loop stability properties with consideration of the dynamics of observer is investigated.The proposed approach has strong applicability in that there is no requirement for accurate plant model,full system state available or any prior information about the uncertainty and disturbance.A tactical missile engineering example is taken as the object and two robust approaches based on disturbance estimation and compensation are applied to the pitch attitude control system design.And performance comparisons with classical H-infinity mixed sensitivity method with the existence of parameter perturbations,disturbance and noise demonstrate the efficacy and robustness of the presented approach.The application of the proposed robust control approach to attitude control system design of a missile three channels is conducted.Since there is strong cross coupling among the three channels,in order to apply the proposed robust approach to the three channels control system design problem,the cross coupling items among the three channels are treated as a source of equivalent input disturbance.Thus the three channels can be decoupled and linearized.The lumped disturbances are estimated and compensated through generalized extended state observers.The corresponding controllers can be designed using robust control approach for the rest linear parts of the three channels to achieve the desired closed-loop performance specifications.In this control framework,the design procedure and the parameters tuning of the three channels are unified,which extremely reduce the complexity of three channels control system design.The approach is employed to the three channels control system design of angle of attack,sideslip angle and roll angle tracking control for a BTT short-range tactical ballistic missile engineering example.Also,some principles for tuning the parameters of the control system are studied,which provides some guidance for applying the proposed method to other controlled plants when selecting the parameters.Finally,a 6DOF trajectory simulation is implemented to validate the performance and potential of the designed control system.Simulation results shows that the designed control system still offers good tracking performance in the presence of various uncertainties,measurement noise and disturbance,which sufficiently demonstrates the effectiveness and robustness of the proposed robust approach based on disturbance estimation and compensation.In conclusion,this dissertation systematically investigates the missile robust attitude control approach.The research results possess some theoretical value for high-precision,strong-robustness control method and provide some design references and ways of engineering realization for aircraft control systems which are subjected to various uncertainties and severe disturbances.