Abstract：For the measurement problem of the 3D long and thin bent tube, an autonomous measurement system consisting of the industrial robot and multiple sensors is presented. An optimized scan path planning algorithm is proposed based on genetic algorithm, to autonomously scan the point cloud of the tube (as a crucial part of the measurement). With the algorithm a collision free scan path is acquired, satisfying that all the segments of the tube can be scanned, and the scan times are as small as possible. And the robot pose at each key scan point is restricted in a certain range around the vertical direction. Moreover, the searching step is updated based on the forward cover coefficient after the generation of each population, and the sampling interval of the new sample individual is also adjusted for quick acquisition of better individuals. In the part of the performance verification of the scan path planning algorithm, the simulation on a bent tube is implemented firstly. Then the scan path planning simulations of cylinder segment and toroidal segment, which are placed with different pose, are conducted. Finally, the simulation and the practical experiment of the scan path planning of a practical car tube are carried out. As the simulation results, the scan length of the best individual increases with the number of iterations, and the coverage ratios of the two kinds of tube segments and the car tube are all above 0.99. The results demonstrate that the number of the planned key scan points is small and the scan volumes of the key scan points can almost scan the tube completely. Simulation and practical experiment results indicate that the algorithm can obtain a suitable scan path for complex tubes.
 张天.基于多目视觉的管路数字化测量方法研究[D].北京:北京理工大学,2014.Zhang T. Research on multi-vision-based digitized measurement method for pipelines[D]. Beijing:Beijing Institute of Technology, 2014.
 González-Madruga D, Barreiro J, Cuesta E, et al. Influence of human factor in the AACMM performance:A new evaluation methodology[J]. International Journal of Precision Engineering and Manufacturing, 2014, 15(7):1283-1291.
 Larry A. New arm is ‘infinitely perceptive’:Portable coordinate measuring machine capabilities continue to grow[J]. Quality, 2004(12):24.
 Luhmann T. Close range photogrammetry for industrial applications[J]. ISPRS Journal of Photogrammetry and Remote Sensing, 2010, 65(6):558-569.
 Grimson W E L, Lozano-Perez T, Noble N, et al. An automatic tube inspection system that finds cylinders in range data[C]//IEEE Conference on Computer Vision and Pattern Recognition. Piscataway, USA:IEEE, 1993:446-452.
 Wang Z Z, Zhang C S. Three-dimensional hand reconstruction by single-shot structured light line pattern[J/OL]. IEEE Access, 2018(6):59881-59890. DOI:10.1109/ACCESS.2018.2875496.
 Wang Z Z, Yang Y M. Single-shot three-dimensional reconstruction based on structured light line pattern[J]. Optics and Lasers in Engineering, 2018, 106:10-16.
 Kjellander J A P, Rahayem M. Planar segmentation of data from a laser profile scanner mounted on an industrial robot[J]. The International Journal of Advanced Manufacturing Technology, 2009, 45(1/2):181-190.
 Rahayem M R, Kjellander J A P. Quadric segmentation and fitting of data captured by a laser profile scanner mounted on an industrial robot[J]. The International Journal of Advanced Manufacturing Technology, 2011, 52(1-4):155-169.
 Larsson S, Kjellander J A P. Motion control and data capturing for laser scanning with an industrial robot[J]. Robotics and Autonomous Systems, 2006, 54(6):453-460.
 Larsson S, Kjellander J A P. Path planning for laser scanning with an industrial robot[J]. Robotics and Autonomous Systems, 2008, 56(7):615-624.
 Yin S B, Ren Y J, Guo Y, et al. Development and calibration of an integrated 3D scanning system for high-accuracy large-scale metrology[J]. Measurement, 2014, 54:65-76.
 尹仕斌.工业机器人定位误差分级补偿与精度维护方法研究[D].天津:天津大学,2015.Yin S B. Research on the graded calibration and accuracy maintenance technique for industrial robot[D]. Tianjing:Tianjin University, 2015.
 王一.面向测量的多关节运动机构误差模型及标定技术研究[D].天津:天津大学,2009.Wang Y. Study on error model and calibration technology of measurement-oriented motion mechanism with multi-joint[D]. Tianjing:Tianjin University, 2009.
 Bauer U, Polthier K. Generating parametric models of tubes from laser scans[J]. Computer-Aided Design, 2009, 41(10):719-729.
 Berenson D, Srinivasa S S, Ferguson D, et al. Manipulation planning on constraint manifolds[C]//IEEE International Conference on Robotics and Automation. Piscataway, USA:IEEE, 2009. DOI:10.1109/ROBOT.2009.5152399.