Research On Active Regulation And Fault Tolerant Control Of Thermal Deformation For Space Reflector Antenna

To carry out continuous and high-precision meteorological observation on the ground for a long time,a reflector antenna,with a diameter of 5-meter and tens of microns of the Root Mean Square(RMS)of surface deformation,should be arranged in geosynchronous orbit.However,the traditional structure protection design can not meet the above requirements due to the influence of the thermal environment of the geosynchronous orbit.Therefore,an active adjusting mechanism should be adopted to realize the antenna reflector protection.This paper studies the coupled control methods,the fault control strategies,and the optimization method of position layout of active adjustment mechanism on the basis of the above.The research content includes the following aspects:1.An layout optimization model of active adjustment of the space antenna reflector is presented.Firstly,under the restriction of the allowable stress of the back-support truss and the reflector,taking the minimum of the root mean square error of the three typical conditions as the objective,a optimization model of the active adjustment mechanism position is established.Secondly,the adaptive fuzzy particle swarm optimization algorithm is designed to solve the optimization model,and the optimal position of the active adjustment mechanism on the reflector support truss is determined.Finally,on the basis of establishing the controlmodel of the space antenna active adjustment system,a Linear Quadratic Regulator(LQR)controller is designed to adjust the thermal deformation of the reflecting surface of the space antenna.2.A fuzzy neural network Q-learning control method based on reference model is proposed to construct the dynamic Q-learning action function and improve its transfer ability.That can be further solved the problem of model uncertainty disturbance in the control model of space reflector antenna active adjustment system.First of all,the algorithm takes the ideal control model of the active adjustment system as a reference,and the Q-learning algorithm is used to adjust the error between the reference model and the actual model,so as to overcome the coupling of the active adjustment mechanism and the influence of uncertainty disturbance.Then,a fuzzy neural network is introduced into the Q-learning method,providing a continuously process for the Q-learning action space,improvement for the generalization ability of reinforcement learning action and the migration ability of the action value function,and obtaining a solution to the problem of uncertain disturbance change in the control model of the spatial reflector antenna active adjustment system.3.An adaptive decoupling control strategy based on fuzzy observer is proposed to solve the problem of the number of parameters identification and high algorithm complexity of the fuzzy neural network Q-learning in the thermal deformation adjustment of space reflector antenna panel.Firstly,the coupling and the external uncertainty among sub-loops are taken as the interference term by introducing the auxiliary state of the system.Then,a selfstructuring fuzzy disturbance observer is designed for each sub-loop to observe and estimate the disturbance online,which is feedbacked into the control law to offset the influence of the disturbance term so as to improve the operation speed of the algorithm and ensure the adjustment effect of the actual model with disturbance changes.Finally,the stability of the method is analyzed with help of Lyapunov stability theory.4.A self-constructing fuzzy Unscented Kalman Filter fault estimation approximation method is proposed to identify the fault information of the fault actuator in active adjustment mechanism of space reflector antenna.Firstly,the governing equation of the fault-free PZT actuator is transformed into an equivalent standard state space equation with faults.Then,the fault information of the actuator is approximated and identified by the proposed method,and the fault function curve is obtained.Finally,the fault threshold is obtained by using fuzzy clustering algorithm,and the fault judgment of a actuator is realized on the basis of it.5.An adaptive fault-tolerant control strategy is proposed for the fault tolerant control of the fault actuators in the space reflector antenna active adjustment system.First of all,an adaptive fault tolerant control law is designed,which is introduced into the control law of the reference model,so as to detect the faults of the actuator online without the help of the fault detection and diagnosis mechanism.Secondly,the Linear Matrix Inequality(LMI)theory is adopted to optimize the normal tracking performance of the error closed-loop system,which makes the fault model asymptotically track the reference model,and identifies the actuator failure rate online.