Research On Vibration Control Method And Experiment Of High-speed Motorized Spindle Based On Piezoelectric Stack

Motorized spindle is the core component of CNC machine tools,and its dynamic performance not only affects its own life,but also directly affects the machining accuracy and efficiency of CNC machine tools.During the machining of CNC machine tools,the vibration of the motorized spindle rotor caused by the working conditions or internal disturbances will seriously affect the dynamic performance of motorized spindle.This thesis is funded by the National Natural Science Foundation of China(Grant number is 51005259 and 51475054).In this paper,the vibration control and experimental methods of motorized spindle are studied through theoretical analysis,simulations and experiments.Firstly,the output model of the piezoelectric stack actuator and the motorized spindle rotor's finite-element model are constructed.The electromechanical-coupling dynamic model of the motorized spindle bearing-rotor-piezo-stack system is established.The state space model of the high-speed motorized spindle bearing-rotor-piezo-stack system is obtained.The transformation method from continuous system state space into equivalent discrete system is discussed.Based on the method of state space expression,the controllability and observability of the model are analyzed.Secondly,based on the electromechanical-coupling state space model of high-speed motorized spindle bearing-rotor-piezo-stack system,the LQG control and H_? output feedback control are analyzed.Considering the poor robustness of LQG control and H_? output feedback control's lack of state estimation,the Kalman filter and the H_? norm are integrated to perform as the state estimator and the system minimization object,a new active vibration control method for high-speed motorized spindle based on mixed H_?/Kalman filter robust state feedback control is proposed.The control effects of LQG control,H_? output feedback control and mixed H_?/Kalman filter robust state feedback control are compared by simulation.Thirdly,based on the mixed H_?/Kalman filter robust state feedback active vibration control proposed,the experimental device of active vibration control is designed.The basic principle and main structure of the vibration control experiment of high-speed motorized spindle bearing-rotor system based on piezoelectric stack actuator are described.Two types of piezoelectric stack actuators with different specifications are used for active vibration control experiments under excitation and no-load conditions.The validity of LQG,H_? output feedback control and mixed H_?/Kalman filter robust state feedback control is verified.The mixed H_?/Kalman filter robust state feedback control has the best vibration control effect and performance robustness.Fourthly,based on the theory and experimental method of active vibration control for high-speed motorized spindle bearing-rotor-piezoelectric stack actuator system,a new adaptive signal separation method based on capacitive bridge circuit is proposed.The adaptive separation of weak sensing voltage signal from coupling voltage of piezoelectric actuator is realised by simulation.The validity of this separation method is verified by experiments,and the vibration signal extracted by this method can be used as displacement signal to realize active vibration control of motorized spindle without displacement sensor.Finally,based on the active vibration control method of high-speed motorized spindle bearing-rotor-piezoelectric stack actuator system,the performance of the semiactive vibration control method with piezoelectric shunt damping is analyzed.On the basis of self-powered SSDI,a new self-powered SSDV is proposed,the adjusting parameters of the shant circuit are optimized by simulation,and the validity of method is verified.Then,a semi-active vibration control experiment of high-speed motorized spindle bearing-rotor system with self-powered SSDV is been carried out.The vibration of high-speed motorized spindle bearing-rotor system can be effectively suppressed by this new piezoelectric shunt damping method without displacement sensor and controller.