December 18, 2015

A 'telehandshake' between the ISS and Earth

Although it is a simple gesture of greeting, it nevertheless remains an extraordinary moment; a handshake between an astronaut on the International Space Station (ISS) and researchers from the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR). Remotely controlled from the ISS, SpaceJustin, DLR's humanoid robot in Oberpfaffenhofen, acted as a proxy in these interactive pleasantries on 17 December 2015. The Russian cosmonaut Sergey Volkov on the ISS and Alin Albu-Schäffer, Head of the DLR Institute of Robotics and Mechatronics, on Earth could see each other, converse and – thanks to force feedback – feel the pressure and movement of the handshake.

"The Kontur-2 technology experiment has allowed DLR to take another major step forward in robotics. This is the first time that we have succeeded in using a humanoid robot to implement force feedback between an astronaut orbiting the planet and a human being on Earth," emphasises Pascale Ehrenfreund, Chair of the DLR Executive Board. "The scientific results of this project will open the door to a broad spectrum of applications – ranging from planetary exploration to more 'earthly' areas in telemedicine and telepresence for people who find themselves in critical situations." In telepresence systems, robot operators use robotic avatars located a long distance away to act in their place – almost as if they were there.

Unparalleled complexity

Never before has a humanoid robot been controlled from space. The Kontur-2 joystick, developed by the DLR Institute of Robotics and Mechatronics, on board the ISS since July 2015, controlled SpaceJustin's arm and provided force feedback. What makes this technology – and the experiment as a whole – so extraordinary is its unprecedented complexity; the space-qualified joystick on board the ISS can be used to transmit delicate force feedback to astronauts in real time. An additional control element on the joystick can close the robot’s hand so that the astronaut can even grasp objects.

ISS – St. Petersburg – Oberpfaffenhofen

Time delay in data transmission is one of the biggest challenges faced by telepresence applications in space. The delay over a distance of roughly 400 kilometres is 30 milliseconds. A specially designed control concept ensures that the lag does not precipitate unstable behaviour that might otherwise cause the system to move in an uncommanded way. The force feedback during the telehandshake at DLR worked so smoothly that the scientists even succeeded in completing another ambitious experiment.

While ISS crewmember Volkov operated SpaceJustin's right arm by remote control, the Russian State Scientific Center for Robotics and Technical Cybernetics (RTC) in St. Petersburg took over the left arm. RTC has an identical Kontur-2 joystick from DLR in its laboratory. Volkov and RTC controlled SpaceJustin together, having the robot pick up a ball and hand it to the DLR team in Oberpfaffenhofen. All three participants were able to feel the contact forces that the other two exerted – the pressure on the ball during grasping, and the release when the ball was handed over.

Robonaut of the future

Telepresence technologies will be crucial to the future of space exploration; astronauts will be able to control a robot performing fine motor tasks while exploring Mars, the Moon or other celestial bodies without ever leaving their space station. Telepresence would even enable ground controllers on Earth to perform maintenance and repair work on satellites.

The telehandshake and the cooperative handover of a ball marked the high point in the Kontur-2 experiment series, designed to test and optimise telepresence technology on board the ISS. Now that this technology demonstration has been brought to a successful conclusion, the DLR Institute of Robotics and Mechatronics is ready to take the next steps. In future, it will be possible to apply telepresent control to operating systems with several degrees of freedom. This would enable control of a system in any spatial direction, and thus usher in a new era of telepresent space robotics; then, the astronaut will be able to control the entire body of a humanoid robot, and not just SpaceJustin’s arm and hand.

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Bernadette Jung

German Aerospace Center (DLR)
Communications and Media Relations: Oberpfaffenhofen, Augsburg, Weilheim
Münchener Straße 20, 82234 Weßling
Tel: +49 8153 28-2251

Jordi Artigas Esclusa

German Aerospace Center (DLR)
Institute of Robotics and Mechatronics
Linder Höhe, 51147 Köln