| CNC machine tools are important processing equipment in the machinery manufacturing industry.However,the friction between the moving platform and the guide rails during the work will affect the processing accuracy of the product.In order to eliminate the adverse effects caused by friction,magnetic levitation technology with no friction and no wear has become a research hotspot in the field of precision machining.However,the magnetic levitation system is highly nonlinear and strongly coupled,which makes the control of the magnetic levitation system very challenging.Therefore,this article takes the vertical supporting part of the magnetic levitation platform as the research object and designs the magnetic levitation system controller to achieve high-performance control requirements.The details are as follows:Firstly,the research status of the magnetic levitation platform at home and abroad is introduced.On this basis,the structure and working principle of the magnetic levitation platform are described.The mathematical model of the single electromagnetic levitation system is established.On this basis,the nonlinear mathematical model is converted by the coordinate transformation theory.In order to facilitate the design of the controller.Secondly,for the characteristics of open loop instability and high nonlinearity of single electromagnetic suspension system,the second-order terminal sliding mode variable structure control strategy is adopted.The nonlinear sliding mode surface is designed and the synchronization error is taken into account,and the super spiral algorithm is used to calculate the control rate.This method effectively weakens the chattering phenomenon,and can keep the magnetic suspension system stable and has strong robustness and anti-interference ability.Thirdly,in view of the coupling problem between each single electromagnetic suspension system supporting the magnetic levitation platform,on the basis of realizing the stable suspension of the single electromagnetic suspension system,a synchronous controller combining a ring-shaped coupled synchronous control structure and fuzzy control is designed.The ring-coupled synchronization control strategy takes into account the tracking error of the single electromagnetic suspension system,and also considers the synchronization error between two adjacent systems.The synchronization error is fed back to the input of the system through the compensation module to achieve the stability of the magnetic suspension platform Suspended.Originally,the fuzzy controller was used as the compensation module,and the magnitude of the synchronization error and its rate of change were used as the input of the fuzzy controller to compensate the input end of the system more flexibly to improve the synchronous suspension performance of the magnetic levitation platform.Finally,Matlab / simulink is used to verify the above two control schemes.The simulation results show that the single electromagnetic suspension system control strategy can quickly suspend the system to the target height and maintain strong anti-interference ability.The synchronous control strategy adopted in this paper is simulated under the same conditions as the proportional gain loop coupling control,deviation coupling synchronization control and adjacent cross-coupling synchronization control.The simulation results show that the fuzzy loop coupling synchronization control has faster response speed and stronger Anti-interference ability. |
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