Research On Key Technologies Of Tool Angle Measurement System Based On Machine Vision

Trade war between China and the United States being increasingly intensified,equipment manufacturing is the foundation of national economy and national industry.Cutting operation is an important part of equipment manufacturing.It is imperative to implement high precision,high speed,high automation and high flexibility of cutting.The tool is an important part of the cutting process equipment.it is very important to clarify the tool angle parameters before cutting,so writer designed a tool angle measurement system based on machine vision,and this system is different from the traditional manual measurement,with high measurement accuracy,fast measurement speed,wide adaptability and other characteristics.In order to build the tool angle measurement system,the main research contents are as follows:(1)Analyze the characteristics of the tool angle,design the overall scheme of the tool angle measurement system and select the hardware of the image acquisition system.According to the requirements of the measurement system,the communication interface,resolution and photosensitive chip parameters of the purchased camera are determined,and the parameters such as resolution,depth of field,interface and focal length of the industrial lens are determined.The shape and lighting mode of the light source are determined,and the fixed scheme of the camera is determined.(2)Researching traditional camera calibration algorithm,propose a camera calibration method based on improved Zhang Zhengyou algorithm,comparing reprojection error the calibration method before and after improved,and explore the calibration process influence about illumination,plate number,calibration plate specifications factors,improving the precision of the cutting tool angle measurement system.The methods of image preprocessing after camera calibration are studied,including tool image grayscale,binarization,image operation and image smoothing.The tool ROI(Region of Interest)can be obtained by these methods.(3)The definition of turning tool edge was analyzed,and the pixel level of cutting tool edge was obtained by Non-maximum Suppression and Hysteresis Thresholding after Gaussian Smoothing filte.It was proposed that a method of pixel subdivision based on the improved Zernike moment algorithm,and the accuracy and precision of sub-pixel edge acquisition based on the improved Zernike moment were compared.After determining the sub-pixel edge coordinates of the cutting tool,the angles of the assumed working face-back plane reference system were calculated,and the important angle parameters in the plane system were calculated by coordinate transformation,so the main deviation Angle,the secondary deviation Angle,,the blade inclination Angle,the rake Angle₀,and the rear Angle₀.(4)The tool angle measurement system is developed,and the experimental platform of the measurement system is set up.Taking turning tool as an example,the feasibility and superiority of the proposed improved algorithm of camera calibration,image preprocessing,tool edge extraction and pixel subdivision are verified.The experimental results show that the tool angle measurement system based on machine vision can achieve a measurement error of less than 0.95 degrees and a single angle measurement time of less than 4s.The tool angle measurement system based on machine vision can be used as a fast and accurate tool angle measurement method.There are 93 figures,14 tables and 100 references in this paper.