German Ground Controllers Use Joystick To Operate Space Station Arm

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A German government-funded robotic arm recently installed on the outside of the international space station has been successfully operated by ground controllers using a joystick in their offices, German Aerospace Center (DLR) officials said.

The Rokviss is a one-jointed arm with a stereo camera attached. It is intended as a proof of concept for subsequent designs for robotic arms that will use off-the-shelf components and lighter weight materials.

Rokviss was launched to the station in December and was installed outside the Russian Service Module in January. After a few early hiccups, in late March it was subjected to a full series of maneuvers.

Despite a six-week shutdown starting in February when the station was repositioned and the Rokviss communications link was interrupted, the system functioned “better than we would have thought,” said Gerd Hirzinger, director of DLR’s Institute of Robotics and Mechatronics of Oberpfaffenhofen, Germany. “We are obviously excited with the performance. Everything is working as we had hoped.”

Hirzinger said March 30 that the early overhead passes have permitted Rokviss program managers only about four minutes of operating time, with up to three over-flights per day. Starting in mid-April, the station’s orbit should permit six-minute visibility periods during favorable orbits, he said.

Rokviss was built by DLR and its industrial partners include Kayser-Threde of Munich and EADS Space Transportation of Bremen, Germany. The entire project was budgeted at 11.5 million euros ($15 million), including about 3.5 million euros in payment to Russia’s Roskosmos space agency and Russian industry for the integration and launch of Rokviss aboard an unmanned Progress supply vehicle and the installation on the Service Module exterior.

Peter Hofmann, space station utilization project manager at Kayser-Threde, said Rokviss’ S-band communications link may find a secondary use in providing two-way communications from the Russian section of the station to ground teams for future experiments unrelated to Rokviss.

Hofmann said the communications link is capable of transmission speeds of 512 kilobits per second uplink and 4 megabits per second downlink, offering a performance not always available from the Russian end of the station.

To date, that idea has not been pursued, but Hirzinger said it remains a possibility, especially for European-provided station experiments that are scheduled to be conducted at the station before Europe’s own Columbus laboratory — with its own high-speed communications capability — is launched in 2007. For this idea to be practical, a ground station would need to be added in Moscow, Hofmann said.

The Rokviss operations contract is expected to last a year. Hofmann said the experiment could provide useful information for future tele-operations on Mars or other destinations. DLR also is hopeful that the Rokviss success will open doors to a future mission of using a remotely guided satellite-repair kit to attach to damaged satellites in orbit.

Hirzinger said the Rokviss camera has already been used to view the portion of the station visible from its Russian Service Module perch. DLR plans to employ Rokviss as part of a space-education program in which students will operate the joystick.