IJAT Vol.17 No.5 pp. 494-503
doi: 10.20965/ijat.2023.p0494

Research Paper:

Posture Optimization in Robot Machining with Kinematic Redundancy for High-Precision Positioning

Shingo Tajima*,†, Satoshi Iwamoto*, and Hayato Yoshioka** ORCID Icon

*Tokyo Institute of Technology
4259-G2-19 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan

Corresponding author

**The University of Tokyo
Tokyo, Japan

March 30, 2023
June 26, 2023
September 5, 2023
robot machining, path generation, industrial robot, kinematic redundancy, trajectory

Vertically articulated industrial robots are suitable for machining purposes owing to their advantages over multi-axis machine tools, such as larger workspace, easier installation, and lower cost. However, the rigidity and positioning accuracy of industrial robots are inferior to those of machine tools, which renders it difficult to maintain the robot posture required for machining operations. This study focuses on improving the accuracy of robot machining based on posture optimization by exploiting the kinematic redundancy of a six-axis vertically articulated robot. To decrease positioning errors caused by static and dynamic external forces during machining, this study proposes a path generation method for a redundant joint that simultaneously considers the static and dynamic rigidity of the machining robot. The relationships between the static and dynamic mechanical characteristics of the machining robot and the redundant angle are illustrated using two maps: a static stiffness map and a natural frequency map. Using these two maps in the proposed path generation method, the redundant angle that can be selected for the robot posture with arbitrary mechanical characteristics is selected. Experimental results confirm that the proposed path generation method can control the priority of reducing static positioning error and vibration amplitude by changing the weight coefficients. In addition, the proposed method can improve positioning accuracy compared with conventional trajectory generation methods for redundant robots.

Cite this article as:
S. Tajima, S. Iwamoto, and H. Yoshioka, “Posture Optimization in Robot Machining with Kinematic Redundancy for High-Precision Positioning,” Int. J. Automation Technol., Vol.17 No.5, pp. 494-503, 2023.
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Last updated on Jul. 23, 2024