Research And Realization On Adaptive Control Of Two-Dimensional Transverse Vibration Of Shafts

External load,mass imbalance,assembly errors,etc.,may give rise to vibration,especially lateral vibration problems on running shafts in equipment such as wind turbine towers,compressors,lathes,etc.Severe such vibration are likely to seriously interfere the running of the shafts so as to interrupt the operation,or even destroy the equipment.However,there is currently no simple and effective means for the two-dimensional lateral vibration control of shafts structure.Subjected to adaptive control regime,this paper,therefore,proposes a semi-active vibration control method and an active vibration control method to suppress the two-dimensional lateral vibration of a shaft.Based on these two methods,two prototypes were designed and tested,and the performance of the prototypes validate the feasibility of the two methods.The main research contents of this thesis are as below:(1)Research on vibration control mechanism.This part analyzes the semi-active vibration control mechanism of mechanical-electromagnetic coordination.The mechanical part uses a cantilever beam spring with an adjustable effective length to determine the main operating frequency band of the device.The electromagnetic part uses electromagnetic coils and permanent magnets to form an electromagnetic spring,which widens the frequency band and provides fine frequency resolution.At the same time,the circular section beam and the annular structure are designed to have the same rigidity in any direction in the transverse plane,so that the two-dimensional lateral vibration can be suppressed.In addition,the active vibration control mechanism that uses centrifugal force as the main power is also analyzed for finding a new measure to cancel part of the external exciting force,so as to attenuate the vibration.The permanent magnet is driven by some electromagnetic coils to perform a circular motion to bring about a centrifugal force.A control algorithm,meanwhile,is used to maintain a proper phase between the centrifugal force and the exciting force to achieve vibration control in the two-dimensional plane.(2)Mathematical model establishment of vibration control.The semi-active vibration control method is actually a self-tuning dynamic vibration absorber,which is simplified to an Euler-Bernoulli beam with a concentrated mass and an electromagnetic spring with adjustable stiffness at the end.The mathematical model of the natural frequency of the dynamic vibration absorber is established.At the same time,the electromagnetic force model between the permanent magnet and the electromagnetic coil is established.In a small displacement range,the relationship between the electromagnetic force and the vibration displacement can be linearized to obtain the electromagnetic spring stiffness.The mathematical model of the active vibration control mechanism is established through force analysis,and the establishment of the active force model can also be carried out based on circular motion knowledge.The limit speed model that the electromagnetic coil drives the permanent magnet can be established from the law of conservation of energy.(3)Prototype design and simulation verification.Based on the semi-active and active vibration control mechanism and mathematical model,in this section,a design and optimize upon main parameters,including the cantilever beam spring size and effective length range,electromagnetic spring size and control current range,is implemented.According to these parameters,the simulation model is established,by which the simulation and numerical calculation results are compared to verify each other and confirm the correctness of the established model.Moreover,a semi-active and active vibration control system is built in Simulink software to simulate the effect of the theoretical vibration control.(4)Prototype testing and validation.Two prototypes of semi-active and active vibration control device have been manufactured and their test systems have been built.Various performances have been tested,including bandwidth,frequency resolution and vibration control effect.By comparing the simulation and numerical analysis results,the proposed vibration control mechanism has been verified and the performances have been evaluated.In the end,errors between the experimental results and simulation results have been analyzed and reasons that can explain these phenomena have been given.Some methods that can improve the prototype design have also been proposed.