Research On Measuring Technology Of Cycloidal Gear Based On Machine Vision

In recent years,the cycloidal drive is widely used in industrial robots,aerospace,medical,machinery and other fields,and becomes the second largest transmission mode.For the measurement of cycloidal gear,the present traditional measurement method cannot meet the industrial requirements.In order to accurately and quickly measure the tooth profile and pitch deviation of cycloidal gear,the theory and method of cycloidal gear machining error detection are studied deeply by visual measurement technology.It provides the basis for the improvement of cycloidal gear processing technic and the transmission performance analysis of RV reducer.The main research contents are as follows:(1)The cycloidal gear visual measurement system was designed.According to the measurement requirements of cycloidal gear,the overall measurement scheme was determined.The hardware system of industrial camera,lens,lighting system,image acquisition card and other optical components selection were completed.At the same time,the software system was designed.(2)An improved Facet subpixel edge extraction algorithm was proposed.Firstly,the rough edge points were determined by threshold segmentation method.Secondly,centering on the rough edge points,Facet gray surface was fitted along the tangential window of edge.The orthogonal transformation algorithm was used to simplify polynomial fitting calculation,and the subpixel coordinate points were determined by using the gray surface feature of step edge.The accuracy of the Facet algorithm was tested by gauge block to decrease from ±0.5 pixel to±0.1 pixel,which proved the effectiveness of the improved algorithm.Finally,the pixel equivalent and light intensity compensation coefficient were calculated by using the gauge block.(3)The cycloidal gear was measured and compared by visual measurement system.According to the improved Facet subpixel edge algorithm,the overall profile of cycloidal gear in the image coordinate system was obtained.Then,the subpixel tooth profile of the cycloidal gear in the physical coordinate system was obtained by pixel equivalent calibration,light intensity compensation and coordinate transformation.Subsequently,compared with cycloidal outline shape by three coordinate measuring method,the difference of the cycloidal profile obtained by the two methods was 10μm,the accuracy of cycloidal gear visual measurement system was verified.According to the tooth profile equation of cycloidal gear,the error calculation model of cycloidal gear were established,and the tooth profile deviation and pitch deviation of cycloidal gear were calculated.Furthermore,the relationship between tooth profile deviation and polar angle was also obtained.It provided the basis for the improvement of cycloidal gear processing technic and the transmission performance analysis of RV reducer.