Optimal Cartesian Contact Force Estimation for Industrial Robots and Its Application to Mechanical Manufacturing

• Applicant: Professor Dr.-Ing. Alexander Verl
• Subject Area: Automation, Mechatronics, Control Systems, Intelligent Technical Systems, Robotics
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 511766869

For industrial, mechanical manufacturing tasks (such as polishing, grinding, deburring, and assembly) with robotic manipulators, the manipulator's end effector must interact with the environment. This interaction requires force control due to limited planning and absolute accuracy. In turn, this control requires the contact force in real-time, for which force/torque sensors (F/T sensors) are used. It is desirable to avoid the use of F/T sensors, since the additional sensor technology results in higher costs as well as a higher probability of failure. An alternative to the use of F/T sensors is the observation of the contact force based on available measurement signals. Since few years, robot manufacturers (such as Fanuc, Mabi Robotic) have been offering industrial robots for mechanical manufacturing tasks that have both motor and joint-side position measurement. This joint-side position measurement in combination with the recent advances in control theory, promise to improve the contact force estimation compared to the state of the art. Within the research project, an optimal contact force estimation based on the moving horizon approach and the recently available joint-side position measurement will be developed. In contrast to the state of the art, the approach is characterized by using a sliding time window rather than just the instantaneous measurements, which yields a superior and more robust estimation. The approach will be validated using a real manufacturing task and compared with the use of F/T sensors.

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