Active Vibration Control Of Flexible Components And Its Application To Spacecraft

With the development of the aerospace industry,the assembly and application of lightweight,large-size flexible components have become a development trend.However,due to the flexible components’ low damping ratio and modal frequency,large-scale and long-lasting vibrations are prone to occur,which affects the attitude and position control accuracy and even causes resonance among multiple structures.Therefore,active vibration control of flexible structures has always been a key fundamental issue in aerospace applications.In this dissertation,combining with the independent research and development project "Simulation of 32-point Excitation Force Control in Modal Test" of research by China Aerospace Science and Technology Corporation,the theoretical analysis and in-depth research is carried out on the spacecraft flexible structure components with piezoelectric actuators from dynamic modeling to active vibration control.The main contents are as follows:In view of the different constraint boundary conditions of the spacecraft flexible components,considering the plane stretching phenomenon,the nonlinear global modal flexible components and the spacecraft attitude dynamic model with flexible components are established by using the Hamilton principle.Considering the lack of modalities caused by the simplification of the modal constraints of the dynamic model based on the Galerkin method,a method of expressing the residual modal as model uncertainty and compensating it through control design is proposed to avoid the influence of control overflow.Aiming at the problem of obtaining vibration mode parameters of dynamic model of flexible components,a real domain second-order Quasi-Newton control method based on modal test multi-point excitation force control system is proposed.For the case of multifrequency disturbance of output signal,and considering the disturbance vibration conduction coupling caused by multi-point excitation,to make the multi-point excitation force control system of modal test achieve the desired excitation force control performance index,a real domain second-order Quasi-Newton iterative controller with proportional harmonic filter is designed based on the real domain transformation method;Furthermore,considering the long iterative period of multi-point excitation control,a real domain iterative controller optimization method is proposed based on fuzzy frequency response matrix.Finally,the control performance of the real domain second-order QuasiNewton controller of the multi-point excitation force control system is verified by simulation.The modal shapes of flexible components are extracted according to the simulation data,and the influence of the accurate mode shapes on the active vibration control is given.Aiming at the problem of active vibration control of flexible components,the stateconstrained sliding mode active vibration control method is proposed which considers distributed disturbance,piezoelectric actuator saturation,model uncertainty,and limited vibration displacement simultaneously.For the case that there is only distributed disturbance in the system,a sliding mode active vibration controller is designed by using nonsingular fast terminal sliding mode surface and exponential reaching law;For the case of distributed disturbance and vibration displacement limitation in the system,based on symmetric barrier function and asymmetric barrier function,respectively,combining with the nonsingular fast terminal sliding mode surface,a state constraint sliding mode active vibration controller is designed;Further,based on the above problems,for the model uncertainty caused by the simplification of the modal constraints of the dynamic model of flexible components and the input saturation of PZT piezoelectric actuator,a state constraint sliding mode active vibration controller based on RBF neural network and the auxiliary system is designed.The stability of the designed controller is proved by Lyapunov stability theory and compared with T-S fuzzy state feedback controller in numerical simulation analysis,which verify that the active vibration control system of flexible components has faster convergence time and higher vibration control accuracy with the designed controller.Aiming at the problem of active attitude vibration control of spacecraft with flexible components,an attitude control method and active vibration control method considering the coupling variables in the model uncertainty and the backlash hysteresis of PZT piezoelectric actuator are proposed.For the flexible spacecraft attitude control subsystem with external disturbance torque,model uncertainty,and attitude actuator saturation,taking into account the coupling phenomenon between attitude and vibration,based on the nonsingular fast terminal sliding mode surface and auxiliary system,combined with the variable upper bound of model uncertainty and adaptive control theory,a finite-time stable adaptive sliding mode attitude controller is designed;For the active vibration control subsystem of flexible components with PZT piezoelectric actuator hysteresis,model uncertainty,distributed disturbance,and vibration displacement constraints,using symmetric barrier function,a state constraint sliding mode inverse backlash active vibration controller is designed based on RBF neural network and nonsingular fast terminal sliding mode surface.The stability of the designed controller is proved by Lyapunov stability theory,and compared with PD controller in numerical simulation analysis,the effectiveness of the designed attitude active vibration control system of flexible spacecraft is verified.At the same time,the designed controller can effectively suppress the undesired vibration of spacecraft flexible components,and the spacecraft attitude convergence speed is faster and the pointing accuracy is higher.