Precision Measuring Method Research Of Linear Motor Mover Position Based On Aperiodic Sinusoidal Striped Image

Permanent magnet synchronous linear motor(PMSLM)servo system is widely used in additive manufacturing,laser processing,glass substrate testing machine,high-precision scanning detection and other precision processing fields because of its fast response,small power loss,high reliability,unlimited travel and other advantages.The precision and real-time of linear motor position measurement restrict the control accuracy of servo system,thus affecting the machining accuracy of products.At present,the displacement measurement of linear motor is mainly based on the displacement sensors such as magnetic grid and grating.They have certain application in the linear position measurement,but there are still many limitations in the practical application due to the high requirements of working environment and installation.Digital image measurement method(DIMM)is a new method of displacement measurement,which can realize non-contact full field measurement,it has the advantages of high precision,strong robustness,little environmental impact,and is widely used in target tracking,image matching and other research fields.The introduction of DIMM into the real-time precise measurement of the actuator position of linear motor is of great significance for improving the feedback accuracy of the actuator position and further improving the machining accuracy of the machine tool.In order to improve the accuracy and anti-interference of the position detection of linear motor's mover from the target shooting source,this thesis constructs a kind of aperiodic sinusoidal stripe image,and studies a mover position detection method based on aperiodic sinuoidal stripe image to realize the fast and high-precision position measurement of mover.This topic mainly carries on the following research:(1)Based on the image measurement technology,the position measurement model of the linear motor mover is established,and the principle of the mover position measurement for the linear motor is described briefly.In view of the fact that there is no gray scale change in fence image within the width of a single stripe,a sinusoidal stripe image is constructed,and the aperiodic sinusoidal stripe image with strong robustness is selected according to the gray level co-occurrence matrix,which is taken as the target image to ensure the accuracy of measurement.(2)According to the characteristics of the mover motion,this paper studies the mover position measurement method of linear motor based on the area array CCD,and explains the principle of image matching based on the area array image,and an image sub-pixel measurement method based on the gradient method of Barron operator is introduced.Simulation verification and result analysis are carried out,the robustness and measurement accuracy of different target images are compared,and the effectiveness of aperiodic sinusoidal stripe image is verified.(3)In order to improve the accuracy,stability and real-time performance of the mover position measurement of the linear motor,the mover position measurement method of the linear motor based on the linear CCD is studied.The linear array CCD camera can directly obtain one-dimensional stripe information by scanning the target image information,which reduces the amount of motion information,and improves the real-time performance of position detection;In addition,the Chirp Transform Algorithm(CTA)image displacement estimation algorithm is introduced to improve the accuracy and stability of position detection.Finally,the accuracy,stability and rapidity of the mover position measurement method based on linear CCD are verified through the experimental results.(4)According to the linear motor mover position measurement system,the area array CCD and line array CCD measurement experiment platform are built respectively.The aperiodic sinusoidal stripe image is taken as the target image,and the object image calibration coefficient is determined according to the calibration system.A series of comparative experiments are carried out,and the experimental results and error conditions are analyzed.The results show that the measurement method based on the aperiodic sinusoidal stripe image can realize the fast and high-precision mover position measurement of the linear motor,and the measurement system has high stability.