Research On Multi Degree Of Freedom Decoupling And Anti-interference Control Of Magnetic Liquid Double Suspension Bearing

The magnetic liquid double suspension bearing adopts two kinds of hybrid support forms of electromagnetic suspension and hydrostatic pressure,which has the advantages of strong bearing capacity,large support stiffness,no friction and wear,fast adjustment response and good active control.However,due to the complexity of the mathematical model and nonlinearity,the coupling of the two systems,and the complexity of the controller,the stability and control accuracy of the double suspension bearings are affected.Therefore,this paper deduces the mathematical model of the five degree of freedom double suspension bearing,and focuses on its multi degree of freedom centralized compound anti-interference and decoupling control system.The main research contents of this paper are as follows:(1)Based on the analysis of the mechanical structure,load-bearing mechanism and control regulation principle of the magnetic liquid double suspension bearing,the linear dynamic model and state space equation of the radial four degree of freedom centralized control system and the axial single degree of freedom decentralized control system are established.(2)For the axial single degree of freedom support system,a discrete geso anti-interference controller is established to estimate the uncertainty disturbance caused by the matched(or unmatched)external interference force in real time.The pole assignment of the axial support system is realized by the state feedback method,and the external interference force is suppressed and eliminated by the feedback interference compensation gain.Considering the sampling period,the control accuracy and anti-jamming ability of the discrete geso anti-jamming controller are verified by simulation.(3)The linear quadratic optimal control state regulator(LQ)and the generalized extended state observer(GESO)are used to construct the composite anti-interference controller for the centralized control of the radial four degree of freedom support system.The state regulation effect of LQ control at different rotating speeds is compared,and the simulation results show that the compensation and suppression effect and control accuracy of the combined anti-interference controller for different types of interference forces.(4)In this paper,the coupling interference mechanism between the radial four degree of freedom support systems is studied,which is regarded as the internal interference of the system and constitutes the lumped disturbance together with the external interference force.Four GESO decoupling controllers are constructed to accurately observe the lumped disturbance on each degree of freedom,and the lumped disturbance compensation decoupling is realized by combining the feedback interference compensation gain.The decoupling effect of the radial four degree of freedom support system is analyzed by simulation and dynamic regulation performance.