Mechnical Design Systems Laboratory, Hiroshima University

There is a growing need for "in-line measurement" of geometric accuracy of the manufactured parts in the manufacturing line. An industrial robot with a touch-trigger probe installed to its end effector can be potentially applied to such an inline measurement as a portable coordinate measuring machine (CMM). However, the absolute positioning accuracy of robots is often very poor compared to the conventional CMMs. This paper presents that the accuracy of robotic touch-trigger probing can be improved by using the kinematic model containing the angular positioning error of each rotary axis as error sources. The measurement accuracy of robotic touch-trigger probing is experimentally investigated in the straightness measurement of a pre-calibrated artefact, placed at various positions within the workspace of the robot. Significant influence of the rotary axis angular positioning errors on the straightness measurement by robotic probing is revealed.

Keywords: Robot, Probe, Accuracy, Kinematic Calibration