The Key Technology Research On Line Structured Light Scanning System Based On AACMM

AACMM(articulated arm coordinate measuring machine) is based on the rotation of the joints and rotating arm, it is non-orthogonal coordinate measuring system with angle measurements as a reference. It possesses the advantages of large measuring space, portability and flexibility. Traditional AACMM uses contacting measurement methods, for some thin-walled, special materials and dimensions smaller holes, slots,and arc, is difficult to meet the measurement requirements. In this paper, our study the key technology research on line structured light scanning key technologies based on AACMM, take use of non-contact scanning method to overcome the lack of contact measurement, can achieve real-time online rapid detection, has broad application prospects.This article relies on a school-enterprise cooperation program between State Key Laboratory of Precision Measuring Technology & Instruments and Hexagon Metro-logy Technology(Qingdao) co. Ltd. The article mainly studies line structured light scanning key technologies based on AACMM, including system design and system modeling, algorithm for extraction of light center, structured light scanning sensor structure parameters of the integrated field calibration method and calibration of connecting portion between AACMM and structured light scanning sensor and so on. The main work of this paper is in the following aspects:(1) The extraction method of structured light strip center line is focused on, a mathematical model of extraction of light strip center is set up, improved algorithm based on gray-gravity method is proposed by combining with the system design requirements, the performance of the algorithm excellent is verified by designing experiments, and algorithm for each sub-extraction time is not more than 28 ms.(2) The intrinsic and extrinsic parameters of camera calibration model were studied. With the actual measurement requirement of products, the calibration of camera is completed based on Zhang Zhengyou's camera calibration thinking.Calibration software of camera is developed. The calibration experiments of camera is designed, and the effects on the intrinsic parameters of camera from calibrated number of images, different focal length and aperture is analyzed.(3) The structured light plane calibration method is focused on, a line structured light scanning sensor structure parameters of the new integrated field calibrationmethod is proposed, a mathematical model of line structured light scanning sensors is set up. According to Zhang Zhengyou's camera calibration thinking combined LM optimization algorithm, the calibration of the camera's intrinsic and extrinsic parameters is completed quickly and accurately. On this basis, accurate calibration is finished by repeatedly extracting the intersection of two laser structured light plane with the introduction of an auxiliary line laser. The feasibility of the algorithm is demonstrated by designing experiments, ensuring scanning probe system accuracy better than 24 um.(4) A new connecting portion relationship based on genetic algorithm calibration method between AACMM and structured light vision sensor is put forward. The mathematical relationships of calibration of connection portion is derived. The mathematical model of connecting portion calibration based on genetic optimization algorithm is build, the feasibility of the method is verified by designed experiments,the error of experiment is less than 10-3.