Robot calibration using a touch probe

A Renishaw MP250 touch probe is mounted on a FANUC LR Mate 200iC industrial robot. The robot probes a grid of 100 points on each of four of the planes of a grade A 9" datum cube from Standridge Granite (costs about $1,400). Some of the probing configurations are used for calibrating the robot using a non-kinematic model (DH parameters as well as stiffness parameters). After the parameters of the new robot mathematical model are estimated, the accuracy of the calibrated robot is validated by probing three 2" datum spheres separated at precisely known distances (measured on a CMM). The spheres are mounted on a plate that is installed in several different orientations (only one is shown in this video). For the 15 distances measured between the centers of pairs of spheres (each distance about 300 mm), the mean error after calibration was 0.152 mm, the maximum being 0.273 mm. The mean error in measuring the diameter of a 2" datum sphere, after calibration, was only 0.026 mm! Special thanks to GE Aviation Bromont (Canada) for lending us the robot.