November 9, 2016

Testing dexterity in a weightless environment

Human beings do not always retain the same level of dexterity in a weightless environment as they would on Earth – not even with practice. This is a familiar, yet still mysterious, phenomenon encountered in human spaceflight: what is the reason for the reduced hand-to-eye coordination in space, and what can be done to compensate these performance deficits? To find out, researchers from the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) have launched an eight-week series of experiments with cosmonauts on board the International Space Station ISS. The experiments will feature the Kontur-2 joystick. It was developed by the DLR Robotics and Mechatronics Center, and was installed on the ISS in July 2015. The system enables force feedback and uses telepresence technology to permit finely tuned remote control of robotic systems, as if the operator were present on site. Several experiments using the Kontur-2 joystick on the ISS to control robots on Earth were successfully completed last year. In the most recent demonstration, which took place in December 2015, the project team operated this technology to perform a precise 'tele-handshake' between the ISS and a ground-based system.

Until now, hand-to-eye coordination has been a particularly critical factor during manual docking manoeuvres involving Soyuz capsules and the ISS. If the automatic system fails, the spacecraft has to be controlled using the TORU system and two joysticks – an extremely tricky manoeuvre that requires many years of astronaut training. Another current application that requires skill is controlling the Canadarm, a robotic arm fitted to the exterior of the ISS. Robotic systems and telepresence technologies are becoming increasingly important in space travel, which is why human beings will need to acquire additional operation skills. "We hope that the new Kontur-2 study will deliver important information to help us acquire greater understanding of human sensorimotor system in a weightless environment. This is absolutely vital in order to safely and efficiently operate telepresence and telerobotic systems in future, and to therefore make our vision of planetary exploration reality", explains project manager Bernhard Weber from the DLR Robotics and Mechatronics Center.

Simple tasks, complex balancing

The series of experiments aims to consider and analyse each and every aspect of movement. To do this, Weber and his colleagues have developed computer simulations involving the easiest possible tasks: cosmonauts are asked to use a joystick to control the cursor on a screen and to perform a variety of target and follow-up tasks. The tested aspects include performance during position control, speed control and, above all, the effects of different joystick settings. After all, the force feedback capability can be used to control the joystick's damping, stiffness and mass at various levels of intensity. The scientists hope that ideal joystick settings will improve sensorimotor skills in a weightless environment.

In order to obtain meaningful results, several cosmonauts are participating in the study: Andrei Borisenko, Sergey Ryzhikov and Oleg Novitsky will perform the same tasks in different orders over a period of eight weeks. The test participants performed the terrestrial pre-tests already, when the Kontur-2 team met with the three cosmonauts last June to conduct the experiments in the Yuri Gagarin Cosmonaut Training Center in Moscow as a precise benchmark to identify any loss of performance in a weightless environment.

Andrei Borisenko and Sergey Ryzhikov have now successfully completed their first trials on board the ISS, and will continue the series of experiments until the end of December. The results will help the DLR scientists to identify the reasons behind the reduced hand-to-eye coordination, develop solutions for a possible compensation system, and continue optimising the Kontur-2 joystick for its use in space.

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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

Bernhard Weber

German Aerospace Center (DLR)
Robotics and Mechatronics Center
Linder Höhe, 51147 Cologne

Simon Schätzle

German Aerospace Center (DLR)
Institute of Robotics and Mechatronics
DLR Institute of Robotics and Mechatronics, Mechatronic components and systems
Münchener Straße 20, 82234 Oberpfaffenhofen-Weßling