Concept of Developing a Gear Selection Tool for Improved Accuracy in Industrial Robotics

The application of robotics has evolved significantly through every industry. Robots do provide a wide range of motion, however their advantage of having lightweight components also limit the rigidity of the tool center point. Compensatory techniques involving joint stiffness determination and model-based predictions is one potential approach while another modern solution is the usage of precision gears. Higher rigidity and lower backlash found in precision gears as compared to conventional gears enable increased accuracy when carrying out production processes with industrial robots. A study at Fraunhofer IWU confirmed this by examining the impact of precision gear on a six-axis robot's accuracy during a milling process. Replacing all gears with precision gear technology or building new robots with them will certainly increase process accuracy. However, with over a half million robots already installed worldwide, there is a definite need to streamline the gear selection while enhancing the accuracy of existing robots with minimal effort and cost. This paper presents a proof of concept to develop a gear selection tool which utilizes robot’s MBS (multibody simulation) model involving gear parameters and process requirements to simplify gear selection for industrial processes. This tool aims to address the question "Which gear(s) needs to be replaced/installed in a robot to achieve the required/improved movement accuracy for an existing or new process?"