Research On Image Detection Of Defects On The Inner Wall Of The Barrel

The influence of inner wall defects of gun barrel on gun performance has been widely concerned by all countries.However,the existing defect detection technology is complex in operation and low in precision.Therefore,it is of great significance to develop a high-precision and convenient defect detection system of barrel inner wall for accurately judging the performance of the gun,which is also the focus of the current research on gun barrel detection technology.In this paper,based on image detection technology and laser displacement sensing technology,the defects on the inner wall of gun barrel were detected with high precision.According to the detection characteristics and technical indicators of the inner wall of the gun barrel,the structure of the chamber-climbing robot was designed,the image acquisition system was used to obtain the defect image,the actual size of the defect was calculated,and the laser displacement sensor was used to collect and calculate the depth information of the defect.The main research contents and results of this paper are as follows:(1)Based on the detection characteristics and technical indicators of the inner wall of the barrel,the structure of the chamber-climbing robot and the motor control module were designed.The structure of the chamber-climbing robot includes a supporting structure,a rotating structure and a transmission structure,which could be placed in the barrel to be tested.The motor was selected according to the design requirements,and the pulse width modulation(PWM)wave was sent by STM32 single chip microcomputer to control the motor rotation.(2)Based on the principle of image detection technology,a defect image acquisition system was designed to realize the acquisition of the defect images on the inner wall of the barrel and the calculation of the actual area of the defects.Under the action of lighting system,CMOS OV5640 camera was used to obtain the image of the defects on the inner wall of the barrel.The parameters of the camera were configured through FPGA,and the obtained defect images were processed,cached and transmitted.The simulation results by Questasim software showed that the image acquisition system can be used normally.In the upper computer,the defect image was grayed out,binarized,morphologically filtered and edge detected.The image size calibration experiment was designed,and the pixel equivalent was obtained by the edge detection method.After that,the actual area of the defect was calculated.The results show that the calculation error of defect area is less than ±1%,which meets the technical index of the system..(3)Based on the laser displacement sensing technology,a defect depth information acquisition system was designed to realize the accurate measurement of defect depth information.The IL-030 laser displacement sensor was used based on laser triangulation method,the amplifier circuit module,AD analog-digital conversion module,USB-to-serial module and power module were designed under the control of STM32 single-chip microcomputer to transmit the defect depth information to the upper computer and process it,and the corresponding depth measurement experiment was designed for verification.The results show that the absolute error of the defect depth measurement system is less than ±0.05 mm,and its relative error is less than±1.25%,which meets the system design index and has high accuracy.