Key Technology Research On Visual Measurement Based On Machine Vision

The study of space object position and orientation measurement is the key issueson the area of real-time navigation, modern control and motion tracking. As anoncontact position and orientation measurement, machine vision measurement gets theadvantage of installing and measuring easily. With the maturation of machine visiontheory and the development of the vision sensors, vision measurement technology hasbeen more widely used in the area of industry, national defense and aerospace. Based onthe existing vision measurement technology, we have studied the camera imaging model,the methods of calibration, features area and corner extraction to finish space objectsposition and orientation measurement and multi-degree of freedom docking simulation.We have built an experimental device system to verify the correctness of the multi-DOFmeasurement method that based on machine vision. The main contents of this paper areas follows.Firstly, calibrate the internal and external parameters of the camera in themulti-DOF docking simulation platform. Analyze the camera projection matrix undertwo different imaging models and the cause of image distortion. Get the cameracalibration parameters on the direct linear method and nonlinear iterative optimization.Secondly, study the extraction of feature region and corners. After thepreprocessing on the original image, isolate the target area with the image backgroundby the technology of regional growth and connected domain method. Then Harriscorners extraction method is used to get the feature points. In order to get a moreaccurate result in the case of the camera optical axis perpendicular to the measuringplane, accuracy comparative analysis to get the center of circle between gray gravitymethod and the least squares fitting method is developed.Finally, design the hardware and software of the simulation platform. The principleand measurement method of multi-DOF platform is proposed under twodifferentpostures between camera optical axis and measuring plane. Experiments aredesigned to verify the correctness of the measurement model and method.