Research On The Camera Vision Measurement Technology For A Cabin Posture Measurement System

At present,the assembly mode of China's spacecraft cabin assembly is still mainly hand-assembling.During the docking process,technical workers are required to adjust the posture of the docking cabin.The process of adjusting the attitude is labor-intensive.By studying the technology of cabin position and attitude measurement,it can lay the foundation for the automatic docking of the cabin and it is of great significance to realize automation of the cabin production.In the context of the “Automatic Docking System for Cabin Sections” of a research institute,a set of systems capable of measuring the posture of the cabin is developed.The purpose of this thesis is to research and test the camera vision technology in the cabin posture measurement system,mainly from the following aspects:We formulate the overall plan of the cabin attitude measurement system.The six basic parameters of the cabin pose are introduced.The requirements for accuracy and response time of cabin posture measurement were analyzed.According to the demand,the overall scheme of the cabin posture and position measurement system is proposed,including the test bench,pose measurement process,software function structure,and system motion control.The design of the camera vision measurement system is performed.The basic principle of camera vision measurement is analyzed,and the method for finding the position difference between the positioning pin and the positioning hole and the rotation angle of the cabin is proposed.Research on the selection and installation of vision measuring devices including industrial cameras,calibration plates and calibration frames.According to the principle of camera calibration,study the camera calibration process.Present the process of image processing.The key technologies of camera vision measurement are studied.The five aspects of camera calibration accuracy,extraction of outline area of pin,position accuracy of cabin photograph,calibration plate installation and visual measurement error correction were studied.The results of the study are as follows: Modeling the camera with the polynomial distortion model can improve the accuracy of the camera calibration;the robustness of the extraction pin contour region is better and the extraction accuracy is higher;the measurement repeatability is 0.006 mm;Photographing position limit,the limit accuracy is 0.02mm;the installation position of the calibration plate can be measured by the camera vision measurement,the measurement error is 0.027mm;error correction of the camera's visual measurement results,the error after correction is at 0.03 mm below.The camera vision measurement is tested.The camera vision measurement system test software is developed and the functions of laser scanning measurement and camera photograph measurement were debugged.The entire system is able to work as expected.The camera vision measurement is tested and the accuracy is verified.The verification results show that the position accuracy of the camera vision measurement is below 0.03 mm,the angle accuracy is 0.01°,the measurement time is about 5s.It satisfies the needs of cabin attitude measurement,and lay the foundation for position measurement of cabin and automatic docking of cabin.