Research On Aircraft Assembly Stepped Difference And Gap Vision Measurement Technique

The assembly stepped difference and gap should be measured during the process of aircraftassembly to control the assembly quality. Currently, there is no digital measuring method to measurethese gaps and stepped differences precisely, and mainly measured by manual labor. Not only it isinefficient, but also its measurement accuracy is low. In this paper, a method based on line structuredlight vision is proposed to measure these gaps and stepped differences precisely, which has theadvantages such as non-contact, fast dynamic response, high accuracy of measurement, highflexibility, strong real-time performance and so on. Its accuracy reached to0.05mm in10mm steppeddifferences showed in measureing experiments. This paper contained issues as follows:(1) A measuring project of aircraft assembly gaps and stepped differences is designed, which besedon line-structured light light vision measurement principle and its mathematic model. The keyconstructional parameters of the system are designed.(2) The camera calibration technology and the structured light planar calibration technology isstudied. The2D calibration planar target method is choosed to calibrate camera parameters, and theplanar target of unknown orientations and the cross ratio invariance principle method is used tocalibrate light planar parameters. A line-structured light calibration algorithm based on geneticalgorithm and second calibration algorithm is proposed, which aimed at overcome some drawbacks inlight planar calibration, like complicated operation, failure of field calibration.(3) A fast light strip and corner characteristics extracted method is studied, which can extract thelight strip and corner characteristics from the images during the process of structured light visionmeasurement and its calibration, fast and accurately.(4) The main hardware components are choosed to construct a hand-held structured light visionmeasuring system, which based on the theoretical and method research above. A calibration andmeasuring software is developed. The experimental result is showed that this system meet themeasuring requirements, reliable and stability running as well.