Research Of On-line Measurement Technology Of Weld Stud's Position And Attitude Parameters

Weld studs are widely used in automobile manufacturing field, car parts, instruments, interior, engine, lamp and others relies mainly on weld stud to install on the body of vehicles, the number of welding studs used in a car can be as much as several hundred. Therefore, it is essential for their position and attitude to be accurate for assembling the remaining components. Deviations of the positions or attitudes from the standard reference pose could cause assembly difficult or even assembling failures, in turn harming the production efficiency and reliability of vehicles. Presently, the position and attitude parameters of a weld stud are mainly measured by artificial means using conventional instruments such as a step gauge, dial indicator, steel rulers, and wedge plug ruler, these have low efficiency and precision and do not satisfy the requirements of online, continuous, and high precision measurement in modern manufacturing industries.In order to realize pose measurement of weld stud, a method based on computer vision is proposed. First, a calibrated camera is used to collect the image of stud, and then through the image processing to extract the coordinate of feature point in the image. Finally, based on the calculation model, position and orientation offset are figured out. Experiment results show that the method is of high maneuverability and accuracy, the position precision and angle precision were ± 0.15 mm and ± 15', and it satisfies the requirement of online, flexible, fast, and high-precision measurement of weld studs' pose parameters in automobile and other manufacturing industries.The main works of this paper are summarized as follows:1. Analyses the characteristics of weld stud and measurement requirements, has been clear about the weld stud pose parameters based on the technology of visual measuring system design requirements and the research purpose and research significance.2. On the basis of the principle of monocular vision technology and binocular stereo vision technology, we designed two kinds of visual technology of stud welding pose parameters measurement scheme, then derived in detail and established a mathematical model for measuring the parameters of weld stud pose.3. According to the requirements of visual measuring system, designs the visual sensor micro controller, the microcontroller control system hardware circuit and software control program has carried on the detailed analysis and design.4. Weld stud image feature extraction method is studied, based on the theory of image processing, we carry out the weld stud image preprocessing and feature information extraction technology research.5. Set up the experimental device, the correctness of the theoretical analysis is verified by experiment. The paper analyzes the factors which may cause measurement error, put forward the developing direction of next step.