Study On A New Fast Roll Angle Measurement Experimental System Based On Talbot-Moiré Effect

Roll angle measurement is widely used in digital machine tools,missiles,ships,aircraft and other fields,such as determining the rotation angle of machine tool spindle,determining the space position of missile or aircraft,etc.At present,the measurement of roll angle has the problems of low accuracy and poor real-time performance.Therefore,high accuracy and real-time measurement are the key problems to be solved urgently in application.Among many roll angle measurement methods,optical measurement method has become a research hotspot in recent years due to its outstanding advantages of non-contact and high measurement accuracy.This paper focuses on the measurement of roll angle based on Talbot-Moiré effect,and develops an experimental prototype for the measurement of roll angle,which can be used to verify the proposed measurement method.At the same time,the high accuracy and real-time measurement are experimentally studied.The idea of rolling angle measurement based on Talbot-Moiré effect is to transform the change of rolling angle into the change of the distance between Moiré fringes.Then the image of Moiré fringes is acquired by image acquisition equipment.Then the distance between Moiré fringes is calculated by image processing method,and the rolling angle can be obtained.The main contents of this paper are as follows:(1)On the basis of in-depth analysis of the principle and characteristics of the formation of Moir é fringes based on Talbot-Moir é effect,a rolling angle measurement method and verification scheme are proposed.(2)Aiming at the complex problem of image processing algorithm of Moiré fringe,on the basis of in-depth study of the characteristics of Moiré fringe image,a method of image sampling is proposed.By selecting some images which can clearly represent the characteristics of Moiré fringe,the amount of image processing is reduced.Aiming at the difficulty of point selection in line fitting,a fringe boundary line search method is proposed,which improves the speed of point selection and simplifies the algorithm.(3)Aiming at the problem of poor real-time performance of image processing methods of Moiré fringes,in order to improve the running speed and make the operation simple and fast,a visual client software was designed,and an image processing program was written in C language.The real-time processing of Moiré fringes,the real-time display of roll angle and intermediate operation results were realized,which laid a foundation for transplanting to various embedded systems.The system test results show that the error of roll angle measurement is less than 90 angular seconds;the real-time measurement time based on C language is less than 500 milliseconds;and the real-time measurement time based on Python language is less than 200 milliseconds.The experimental results show that the proposed measurement method has high accuracy and the measurement time can meet the requirements of real-time measurement.