Accuracy analysis of SCARA industrial robot based on screw theory

Based on an analysis of error sources of industrial robots, we build a pose error model of industrial robots with screw theory, which overcomes the defect that the error on the y-axis could not be reflected by the classical D-H parameter method. Given the error sources which influence the end-executor´s accuracy, we established a screw representation of the static error caused by the structural error and transmission error and the dynamic error model which is caused by the inertia force and gravity. The model based on Selective Compliance Assembly Robot Arm (SCARA) robot is verified by the results of error diagrams drawn by MATLAB. The curves demonstrate that the dynamic error should be given enough attention when the static accuracy is high, and the dynamic error can be eliminated through controlling the direction of the static error. The error model provides an effective theoretical support for the design of industrial robots with different accuracy requirements.