Experimental Analysis of Robot Base Frame Identification Methods

For many industrial applications (e.g. machining, drilling, pick-and-place, etc.), robot’s poor absolute accuracy has to be enhanced through calibration processes. These processes involve measurement devices, mostly Laser Trackers, which measure the position of a Spherical Mounted Reflector, usually attached on the flange of the robot, in a virtual measurement frame associated with the Laser Tracker. However, calibration processes require to know the position of the flange of the robot in the robot’s base frame. Thus, there is a need for robot base frame identification methods. The objective of this paper is to provide both qualitative and quantitative elements to determine which method is the most suitable for robot calibration. Five different methods are discussed, and based on a qualitative analysis, three of them are experimentally compared, both on repeatability of the method and accuracy.