Research On Driving Control Of Hybrid Magnetic Levitation Needle

In order to further improve the knitting efficiency of existing knitting machines and equipment,this paper combines the working principle and knitting process of traditional computerized flat knitting machines,and designs a magnetic levitation needle drive controller for the hybrid array type magnetic levitation needle drive structure,which can control the size and direction of the current in the electromagnetic array coil with the lateral displacement of the machine head,so as to control the needle to complete the knitting trajectory in real time,and then complete the specified knitting action.This controller can control the current level and direction in the electromagnetic array coil with the lateral displacement of the machine head,so as to control the knitting needle to complete the knitting trajectory in real time and then finish the knitting action.First of all,the current-displacement mathematical model of single needle and multi-needle is established through the study of traditional computerized flat knitting machine and combined with the driving principle of hybrid array type magnetic levitation flat knitting machine,and the kinematic equation of permanent magnet needle is obtained,which provides an important theoretical basis for the study of the motion law of permanent magnet needle.And the numerical model of currentdisplacement of single needle is obtained by experiment.Secondly,we design an array type solenoid coil current controller based on STM32 main control chip and PWM switch type power amplifier for the control of the solenoid coil current driving the magnetically levitated knitting needle by combining the single needle driving model.Combined with the conventional computerized flat knitting machine knitting process,a hybrid magnetic levitation flat knitting machine knitting process is designed and a control scheme for stepping needle drive is proposed.The needle drive control board was designed and fabricated,and the control system program of the drive board and the GUI interface of the upper computer were written.Then,the system and the PID closed-loop control simulation model are built in Simulink software to obtain the timing diagram of the solenoid coil current variation by giving the reference excitation current.The simulation results show that the controller designed in this paper can provide fast and stable control of the solenoid coil current driving the magnetically levitated knitting needles.Finally,a single-needle drive coil current-displacement test platform is built to obtain the numerical model of coil current-displacement by experimental methods and compare it with the theoretical model.A single-needle stepper drive trajectory test platform was built to verify the single-needle stepper trajectory,and the experimental results basically matched with the expected design effect.A prototype experimental platform was also built to verify the rationality and feasibility of the control scheme.