Vision Measurement Technique For Position Deviation Of Parallel Holes With Different Planes In Parts

Parts with different parallel holes are widely used in industrial field,such as the common engine box and the compressed chassis of household appliances(refrigerators and air conditioners)etc.The installation holes of the different surface shafts are generally parallel in axial direction and irregularly distributed in steps.In order to realize the function of the product the shaft holes and the high speed moving crankshaft will cooperate with each other.The deviation parameter of the installation holes of the parallel shafts of these parts(diameter,hole spacing,hole depth)is the key to the quality of the products.The traditional measuring methods mainly include three coordinate measuring machines or special measuring equipment.These kind of measuring methods have the disadvantages such as many measuring points,complex steps,time-consuming and low efficiency,and the contact measurement is easy to cause the surface damage of parts and the measurement equipment wear.With the development of machine vision technology,stereo vision measurement has attracted much attention because of its high efficiency,high precision and strong robustness.In this paper a method for measuring the position deviation of parallel holes in different parts was proposed based on binocular vision measurement technology.In this paper,a binocular vision measurement system was developed to study the shape and position deviation of parallel holes in different parts.And further research was carried out on the key technologies such as binocular vision calibration,image feature processing,stereo vision matching and 3D measurement.The high precision binocular vision calibration and accurate stereo vision matching were realized,and the measurement of the shape deviation of parallel holes in large size parts was completed.The experimental results showed that the binocular vision system has better measurement accuracy of 0.11mm,which verified the correctness of the visual measurement scheme in this paper.The mainly work are as following:(1)According to the situation of measured parts,the binocular vision measurement system was designed and image acquisition system was development.(2)Based on the array of dots target calibration,a highly efficient and high-precision binocular vision calibration algorithm was developed and the system calibration was completed.(3)The three-step identification method of "rough extraction-optimization location-fine extraction" was proposed to complete the accurate extraction of the hole characteristic parameters.(4)A stereo matching algorithm based on the geometric distribution of circular hole feature was proposed to obtain accurate stereo matching results.(5)Based on the developed binocular vision measurement system,the measurement of the position deviation of parallel holes with different planes in parts was completed,and the parts as the prototype,the high precision measurement system hardware configuration was deduced and select.