On-Ground Dynamics Parameter Identification and Force Distribution Analysis of a Gravity-Compensated Space Manipulator Robot

Robotics is primed to play a crucial role in future space missions. By performing tasks such as on-orbit servicing, inspection and de-orbiting, space robotics can enable a sustainable use of Earth’s orbits. The DLR’s Compliant Assistance and Exploration SpAce Robot (CAESAR) is a light-weight, dexterous robot with seven degrees of freedom designed for on-orbit servicing in the Geostationary Earth Orbit (GEO). As CAESAR is designed for microgravity, it requires external gravity compensation to operate on-ground within joint torque limits. The CAESAR laboratory at Oberpfaffenhofen (Munich, Germany) uses a cable-driven parallel robot, the Motion Suspension System, to test and validate CAESAR.

Accurate system identification is key for safe and precise task-execution using model-based control. Especially mass, center of mass, and inertia parameters are error-prone when derived from CAD only. Therefore, the goal of this Master’s thesis is to develop methods for on-ground parameter identification of the CAESAR space manipulator considering the influence of the gravity compensation mechanism. Combining robot dynamics, control and experimentation, this thesis is a unique opportunity to delve into the intriguing problem of on-ground testing and validation of space robots.

Experience and qualification

• Enrolled in a Master’s degree in robotics, computer science or a related field
• Knowledge of C++ and MATLAB/Simulink
• Optional: Experience with robot hardware, and with robot identification in particular
• Optional: Experience with Beckhoff TwinCAT 3

Tasks

• Evaluation of relevant robotic parameters affecting the robot position/force performance
• Implementation of a robot identification strategy given the constraints of the CAESAR ground robotic platform
• Performing experiments and gathering data for the identification
• Working in collaboration with the CAESAR team to understand and model the force distribution of the Motion Suspension System (MSS) on

Contacts