Novel kinematic model of a SCARA-type robot with bi-directional angular positioning deviation of rotary axes

This paper proposed a kinematic model and its calibration scheme to further improve an industrial robots absolute positioning accuracy over the entire workspace. To demonstrate effectiveness in simplified kinematics, this only targets SCARA (Selective Compliance Assembly Robot Arm)-type robot. The includes not link length errors rotary axis angular offsets, widely known as Denavit-Hartenberg (D-H) parameters, but also “error map” of deviation each axis, modelled function command position, rotation direction influence backlash. is identified by measuring end-effector position laser tracker with indexing at prescribed positions. verify validity model, compensation based on it experimentally investigated. By compensation, robot’s average error was reduced 33% 0.034mm. Furthermore, demonstrates that can be extended radial motion, axis-to-axis cross talk, three-dimensional orientation lines.