Research On Key Technology Of Controllable Light-pen Measuring System

The Light-pen coordinate measurement system is a portable on-line measurement equipment,achieving spatial point coordinate measurement based on machine vision technology.In addition to its high accuracy and wide measuring range,the portable,flexible operation and excellent measurement of hidden points make Light-pen an important technical branch of coordinate measurement.Based on years of painstaking research,our research group has developed two generations of monocular-type light pen measurement system,but the measurement accuracy is low,less than the international advanced level.This paper mainly focuses on the second generation Light-pen measurement system,investigates the influence factors of the error,and explores the related technical improvement scheme.Then the third generation of the luminous controllable Light-pen coordinate measuring system is proposed.The design work and key technology research are carried out,and the measurement accuracy of new Light-pen system is proved achieving significant improvement.The main work of this paper is as follows:1.This paper analyzes the Light-pen error factors in combination with the Light-pen measurement principle.The influences on system measurement accuracy by(1)the location error of the projection of the light target center(2)the position error of the light target,are simulated by simulation experiments;the two error sources are researched in depth.2.The solution of the luminous controllable Light-pen system is presented,and the new Light-pen system is designed.The hardware control system of the luminous controllable Light-pen is designed;the new image matching algorithm of the Light-pen is presented;two key technologies of the simultaneous lighting-espousing and double-exposure sampling of the Light-pen and the camera are put forward.3.The problem of the localization of infrared LED central projection is researched.The adaptive light-emitting technology is proposed to achieve the ideal imaging effect automatically;a Gaussian surface fitting method with threshold is proposed,which realizes the high-precision localization of the projection of the light target center.4.The calibration of light target position is researched.In this paper,a new calibration method of the center position of the optical target is proposed,based on the moving light pen by use of CMM;the comparison experiment proves that the new calibration method has higher accuracy than the traditional method.5.The system experiments are done,and the results show that the accuracy of the new Light-pen system is better than that of the second generation one,the new Light-pen has reached a high level of accuracy.The repeatability accuracy of the center of projection of the optical target is better than 0.05 pixel,and in the range of 1.5m-9m,the residual error of the circle diameter measurement of 63.521 mm is better than 0.085 mm,and the residual of the 500 mm gauge is better than 0.12 mm.