Development of a System for Measuring the Thickness of Free Curved Plates – Measurement Posture Planning Using C-Space –
Yurie Okugawa*, Naoki Asakawa**, and Masato Okada**
*Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
**Faculty of Mechanical Engineering, Institute of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
Although it is important to evaluate the thickness of a product made on a press in order to evaluate the mold, there is currently no appropriate system for measuring the thickness of a free curved plate. This study details the development of an automatic measurement and evaluation system for measuring the thickness of free curved plates. The system uses laser displacement gauges and an industrial robot to measure the thickness of a plate. While the system has been capable of measuring workpieces with relatively simple shapes, there have been collisions between the laser path and workpieces with more complicated shapes, owing to geometrical limits of the gauges in terms of measuring posture. This paper proposes a new method of detecting and avoiding collisions by changing the posture on the basis of CAD data when measurements are taken. In this method, not only the geometrical characteristics of the laser path but also the measuring error characteristics of the gauges stemming from measuring posture are considered. In addition, a continuous measuring path with changes in posture to avoid collision is devised. Experimental results confirm that the proposed method does make it possible to measure the thickness of workpieces with complicated shapes.
-  Ultrasonic Thickness Gauge,
-  JAZ,
-  A. Makinouchi, “Sheet metal forming simulation in industry,” J. of Materials Processing Technology, Vol.60, Issues 1-4, pp. 19-26, 1996.
-  G. Gentar, T. Pepelnjak, and K. Kuzman, “Optimization of sheet metal forming processes by the use of numerical simulations,” J. of Materials Processing Technology, Vols.130-131, pp. 54-59, 2002.
-  JSTAMP,
-  K. Chung and K. Shah, “Finite element simulation of sheet metal forming for planar anisotropic metals,” Int. J. of Plasticity, Vol.8, Issue 4, pp. 453-476, 1992.
-  N. Alberti, L. Fratini, “Innovative sheet metal forming processes: Numerical simulations and experimental tests,” J. of Materials Processing Technology, Vol.150, Issues 1-2, pp. 2-9, 2004.
-  N. Asakawa, S. Ikejima, F. Murata, and M. Hirao, “Development of a Free Curved Plate Thickness Evaluation System Using a Robot – Verification of Principal of Measurement –,” Proc. of Int. Conf. on Leading Edge Manufacturing in 21st Century 2009, 5, pp. 155-160, 2009.
-  T. Lozano-Perez, “Spatial Planning: A Configuration Space Approach,” IEEE Trans. on Computers, C-32, 2, pp. 108-120, 1983.
-  T. Lozano-Perez, “A Simple Motion-Planning Algorithm for General Robot Manipulators,” IEEE J. of Robotics and Automation RA-3, 3, pp. 224-238.
-  K. Kondo, “Motion planning with six degrees of freedom by multistrategic bidirectional heuristic free-space enumeration,” IEEE Trans. on Robotics and Automation, Vol.7, No.3, pp. 267-277, 1991.
-  L. E. Kavraki, P. Svestka, J. C. Latombe, and M. H. Overmars, “Probabilistic roadmaps for path planning in high-dimensional configuration spaces,” IEEE Trans. on Robotics and Automation, Vol.12, No.4, pp. 566-580, 1996.
-  Z. Yao and K. Gupta, “Path planning with general end-effector constraints,” Robotics and Autonomous Systems, Vol.55, Issue 4, pp. 316-327, 2007.
-  N. Asakawa and Y. Kanjo, “Collision avoidance of a welding robot for a large structure – Application of potential field –,” Int. J. of Automation Technology, Vol.7, No.2, pp. 190-195, 2013.
-  Japanese Patent Disclosure, H07-280526, 1995.
-  K. Takasugi, T. Kumasaka, and N. Asakawa, “Development of Platform-Independent Open CAM Kernel,” Proc. of Int. Conf. on Leading Edge Manufacturing in 21st Century 2011, 6, 3354, 2011.