High Accuracy Analysis of SCARA Industrial Robot Based on Screw Theory

Abstract

Error sources which influence the end-executor’s accuracy are summarized. Based on an analysis of influence caused by the structural error and transmission error, we build a pose error model of industrial robots with screw theory. If regarding the inertia force of the robot system as the external force, the robot system will become a static system. The rigidity can be analyzed using the screw theory, then we establish the dynamic error modle which is caused by the inertia force and gravity. After the error parameters which influence the static error of Selective Compliance Assembly Robot Arm (SCARA) robot are expressed by two-dimensional discrete variable, error space of the end-executor’s track of robot are made. Position error which influenced by the error sources are analysed by comparision of difference. Total accuracy can be improved through controlling the error direction of the static error to counteract the dynamic error's influence. The error model provides an effective theoretical support for the design of industrial robots with different accuracy requirements.