A Walking Space Robot for On-Orbit Satellite Servicing: The ReCoBot

A key factor in the economic efficiency of satellites is their availability in orbit. Replacing standardized building blocks, such as empty fuel tanks or outdated electronic modules, could greatly extend the satellites' lifetime. This, however, requires flexible robots that can locomote on the surface of these satellites for optimal accessibility and manipulation. This paper introduces ReCoBot, a 7-axis walking space manipulator for locomotion and manipulation. The robot can connect to compatible structures with its symmetric ends and provides interfaces for manual teleoperation and motion planning with a constantly changing base and tip. We build on open-source robotics software and easily available components to evaluate the overall concept with an early stage demonstrator. The proposed manipulator has a length of 1.20 m and a weight of 10.4 kg and successfully locomotes over a satellite mockup in our lab environment.

A practical DMPs Implementation for Skill Creation and Teleoperation with Assistive Manipulators

Assistive robotic manipulators are becoming increasingly important for people with disabilities. Teleoperating the manipulator in mundane tasks is part of their daily lives. Instead of steering the robot through all actions, applying self-recorded motion skills could greatly facilitate repetitive tasks. Dynamic Movement Primitives (DMP) are a powerful method for skill learning. For this use case, however, they need a simple heuristic to specify where to start and stop a skill without additional sensors. This paper provides the concept of local, global, and hybrid skills that form a modular basis for composing single-handed tasks with ease. A focus is on presenting the necessary mathematical details to support custom implementations with assistive robot arms. Experiments validate the developed methods for scratching an itchy spot, sorting objects on a desk, and feeding a piggy bank with coins. The paper is accompanied by an open-source implementation at https://github.com/fzi-forschungszentrum-informatik/ArNe