An optical system to measure the end effector position for on-line control purposes

This article describes an optical system to measure the coordinates of a manipulator’s end effector, which can move in a horizontal plane of approximately 1 × 1 m2. Two rotatable laser beams track a retroreflector pair, mounted on the end effector. The coordinates are calcu-lated from the measured beam rotations. The resolution and reproducibility of the coordinate measurement is 0.05 mm. The maximum tracking speed mounts up to 5 m/s. Using components similar to those applied in CD players, the total cost of all mechanical, optical, and analog elec-tronic components can be kept as low as $3000. On an IBM AT-compatible PC, it takes 1 ms to calculate the x and y coordinates from the measured signals. 1