Study On Measurement Of Barrels’ Axes Based On Computer Vision

Barrel is a kind of component which is likely to produce plastic bending.In order to provide references for improving the later structure design of barrels,a measurement system for the minor-caliber barrels,based on computer-vision,is designed.The barrels’ axes are measured and analyzed from two aspects: the straightness of the barrel at rest and the single barrel’s muzzle vibration at high-speed rotation.The main work accomplished in this paper is as follows:(1)From the research background of barrel straightness and muzzle vibration measurement,appropriate schemes of barrel straightness visual measurement based on collimated laser and single barrel’s muzzle vibration measurement based on computer-vision are designed,according to the design requirements and barrel’s minor diameter.(2)According to the schemes,hardware compositions and corresponding requirements of the two measurement systems are analyzed.Bullet shaped laser,image acquisition system and centering structure of the barrel straightness measurement system are selected or designed.Also,high-speed industrial camera,adjustable holder and optical vibration-isolation table of the barrel straightness measurement system are selected or designed.Two experimental platforms are set up by using the parts selected.(3)The methods of image processing used in computer vision measurement are introduced and compared.The procedures of image processing in barrel straightness measurement including image filtering,laser spot contour detecting and center positioning are determined.In muzzle vibration measurement,images are processed according to the order of image filtering,image enhancing and center positioning of circles at muzzle.(4)The straightness evaluation methods recommended by the national standard are introduced,and the least square method is selected to evaluate the straightness of the barrel.In accordance with the requirements,the muzzle vibration is defined as the maximum deviation between the ideal trajectory and the actual trajectory in the range of[-80°,-100°].By using the experiment platforms built,the calibration schemes of image acquisition system of the straightness measurement system and the high-speed industrial camera of the muzzle disturbance measurement system are designed,and the calibration experiments are completed respectively.Finally,by combining theory and experiment,the measurement accuracy of the barrel straightness measurement is verified,and the system overall measurement accuracy is 133.853μm.The repeatability of the muzzle vibration measurement is also tested by experiments,and the data show that the repeatability of the system is 8.1μm.The results indicate that the two measurement systems have met the design requirements.The project has passed the final acceptance on the scene and has been in use.