Improving the dynamics of industrial robots by adaptive pretensioning of joint gears

• Applicants: Professorin Dr.-Ing. Nejila Parspour; Professor Dr.-Ing. Alexander Verl
• Subject Area: Production Automation and Assembly Technology ; Automation, Mechatronics, Control Systems, Intelligent Technical Systems, Robotics
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 451271315

Industrial robots (IR) offer significant advantages over conventional machine tools, such as a larger workspace, greater flexibility and lower costs. However, their lower accuracy compared to conventional machine tools limits the application potential. Particularly for machining tasks where precision is crucial, the path accuracy of IR is inferior to that of machine tools by a factor of 100 to 1000. This limitation prevents the widespread use of IR in many machining processes. The main reason for the limited accuracy is the non-linear dynamics of the gearing in the robot joints, which is characterized by a pronounced hysteresis behavior. The proposed project aims to investigate how the dynamics and accuracy of industrial robots in machining processes can be improved by a novel drive concept. In the first funding period, the requirements of robot machining were assessed experimentally and, based on this, a new type of drive system for robot joints based on the electrical preloading of multiple individual drives was developed. The novel drive system, which provides a significant increase in stiffness in all operating states, is now to be integrated into the base joint of an industrial robot. In addition to the design challenges, the integration into the robot control will be addressed as well as an optimization of the drive and preload control. To conclude the project, the concept is to be examined in various machining processes and the achievable increase in performance quantified.

• DFG Programme: Research Grants
• Co-Investigator: Dr.-Ing. Armin Lechler