Control Algorithm Researches And System Design Of Maglev Intelligent Spindle For Machine Tool

The machining technology of five axis machine tool represents the core competitiveness of the national manufacturing level,while the spindle is the core part of the machine tool.The traditional mechanical spindle is prone to chatter in the process of thin plate milling,and forming rough workpiece surfaces.Serious vibration will shorten the service life of spindle tool.An active magnetic intelligent spindle with active control which has become a research hot-spot and a powerful candidate of a novel spindle of “intelligent machine tools”.An active magnetic bearing is a complex non-linear mechatronics system which has the characteristics of open-loop instability and nonlinear model,and is easily affected by external disturbance.It is a frontier and challenging work to build a magnetic bearing machine tool system with active control characteristics and design an intelligent controller to meet the processing performance of the machining system.Focusing on the actual engineering requirements of intelligent manufacturing under machine tool processing,this research develops the intelligent magnetic bearing and its control system that can meet the needs of five-axis machine tool,and designs the highperformance suspension and rotation control algorithm of magnetic levitation.As a result,it realizes the excellent overall performance of machine tool-intelligent magnetic levitation motorized spindle system.According to the research objectives of this project,the following work has been completed in this thesis:The basic working principle of the magnetic suspension spindle system is briefly described by analyzing its control framework.The hardware and software controller system based on DSP chip is designed for the integration of machine tool and magnetic intelligent spindle.The basic dynamics model and nonlinear characteristics of the active magnetic bearings are introducedFor the problem of interference force and unmodeled dynamics in AMB system,an extension state observer is developed to estimate the external interference and internal uncertainty,and the magnetic levitating bearing closed loop systems with linear active disturbance rejection control(ADRC)and nonlinear sliding mode control are constructed.In order to present the advantage of the proposed method on resistance to interference investigation,the influence of parameter selection to the controller bandwidth,and the response of the closed-loop system under the unbalanced effect are discussed in magnetic bearing systems.It ensures the stability of the magnetic bearing system under external interference.In view of the inaccuracy of the linearization model of nonlinear electromagnetic force in the whole air gap,a serial of sub-systems of different operating points are established to approximate the nonlinear model of AMB in virtue of the interval type-two fuzzy model.The corresponding fuzzy control law is designed for AMB system.Based on Lyapunov theory,the stability conditions of the linear matrix inequality(LMI)of the controller,especially under the saturation constraint are demonstrated.The experiments prove that the proposed method can effectively improve the suspension performance of AMB which guarantees the suspension support foundation of the spindle rotor.Aiming at dealing with the unbalance effect in the rotating operation of AMB-rotor system and the problem of the lack of speed sensor in the actual scene,the characteristics of the unbalance effect are analyzed.Then,a synchronous signal processor is designed to extract the synchronous signal of vibration and estimate the real-time rotating speed where the effective of estimator is analyzed.The unbalanced vibration suppression framework based on vibration compensation is constructed for reducing the unbalanced vibration of AMB system,which lays the foundation for high quality machining.Finally,relying on the designed embedded hardware and software control system,the actual performance of milling process is verified at the rotating speed of 24000 rpm which reveals performance of the intelligent spindle-machine tool system.This thesis develops a magnetic intelligent spindle control system for the multi-axis machining machine tool of complex curved surface parts.The efficient and practical suspension and rotation control algorithms are designed to guarantee the system performance,that provides an alternative solution for the next generation of spindle in intelligent manufacturing.