Approach On Fault Tolerance And Disturbance Rejection Based Ram-type Wingless Supersonic Missile Control System Design

Ram-type wingless supersonic missiles are one of the most important modern national defense as its high control accuracy,high robustness,high survivability and low cost,which leads the future development of missile weapon systems.Taking ram-type wingless supersonic missiles as the object,and based on their dynamic characteristics and related constraints,this thesis conducts deep research on disturbance rejection and fault-tolerant reconfigurable control system design methods against internal and external disturbances and uncertainties,as well as partial loss of effectiveness failures and total loss of effectiveness failures of actuators faced during complex flight tasks.The symmetric cascade model of ram-type wingless supersonic missile based on control problem is established.According to the characteristics of wingless supersonic missile,the symmetric cascade coupled system model is derived and established for the sake of under-actuation control.The problem formulation of control system design is described.Meanwhile,the velocity angular rate and yaw angular rate are adopted as control objective variables.Considering the constraints of ramjet working conditions on angle of attack and sideslip angle,the saturation function is designed in the guidance phase.The actuator model and actuator failures of missile are defined to describe the over-actuated,fully-actuated and under-actuated missile system due to partial loss of effectiveness failures and total loss of effectiveness failures of fin servos.Based on the above,the control objectives are proposed.Disturbance rejection based linear control methods are proposed.According to internal and external disturbances and uncertainties,as well as partial loss of effectiveness failures and total loss of effectiveness failures of actuators faced by the missile,the equivalent-input-disturbance theory and definition from disturbance estimation based control is introduced.On the basis of equivalent-input-disturbance system,equivalent-input-disturbance and generalized extended state observer based control in time domain and equivalent-input-disturbance and H? based control in frequency domain are proposed with guaranteed stability and superiority analysis.Considering the characteristics of missile system and attitude dynamics in three channels,the control systems in pitch and yaw channel are designed on time domain method,and the control system in roll channel are designed on frequency domain,respectively.A reconfigurable fault-tolerant nonlinear control method is proposed.Considering the proper-actuated missile system resulting from total loss of effectiveness failures of actuators,the linearization diffeomorphism model is established with roll angle as a stable control variable to avoid zero dynamics.Backstepping method is applied to control system design with extended state observer adopted to estimate and compensate the lumped disturbance,which forms the basic control strategy.According to the under-actuated missile system resulting from total loss of effectiveness failures of actuators,the shape variable is introduced.The under-actuated system under different actuator total loss of effectiveness failure patterns is reconfigured to cascade model with roll angle as the shape variable and intermediate variable to change control input actuation.On a multi-model basis,the failure pattern selector is proposed with designed identification adaptive law to realize control system reconfiguration.Meanwhile,the nonlinear saturation problem of fin deflections is resolved through auxiliary system design with Nussbaum function technique.In addition,the global bounded stability of the designed control system is proved through Lyapunov stability analysis.The parameter design of control system and numerical simulation under different failure patterns are conducted.The parameters of linear and nonlinear control systems are designed and analyzed based on missile dynamic characteristics.Considering the proper-actuation failure patterns,the extreme bias simulation and Monte-Carlo simulations are implemented.The effectiveness of disturbance rejection based control system and reconfigurable fault-tolerant control system are validated in the presence of partial loss of effectiveness of actuators,total loss of effectiveness of single actuator,gust disturbance,sensor noise and other parameter bias with both satisfactory performance,and the nonlinear control system has better transient process.Considering the under-actuation failure patterns,the simultaneous failure scenarios and the series failure scenarios are implemented to verify the reconfigurable fault-tolerant nonlinear control system.The simulation results shows that the control system can reconfigure the system model and adjust control strategy with a fast response to overcome disturbances and uncertainties and realize desired tracking performance and fault-tolerant capability under total loss of effectiveness of two actuators.The thesis shows promising prospects and theoretical significance on practical engineering application to ram-type wingless supersonic missiles.Meanwhile,the research provides technical reserve and support for under-actuated control of symmetric model system and fault-tolerant control for actuator failures.