ROKVISS Verification of Advanced Tele-Presence Concepts for Future Space Missions

Transcription

1 ROKVISS Verification of Advanced Tele-Presence Concepts for Future Space Missions ASTRA 2002 Klaus Landzettel, Bernhard Brunner, Alexander Beyer, Erich Krämer, Carsten Preusche, Bernhard-Michael Steinmetz, Gerd Hirzinger DLR Oberpfaffenhofen Insitute of Robotics and Mechatronics D Wessling

2 "The goal of ROKVISS is to test and verify the long-term reliability of a new generation of lightweight robotics components in free space operation. "The intelligent robotic joints were developed at DLR s Institute of Robotics and Mechatronics in Oberpfaffenhofen. "The new light weight robot is able to handle loads equal to its own mass, while conventional robots only achieve a ratio of roughly 1:10 to 1:15.

3 DLR s new generation of light weight robots

4 7th ESA Workshop on Advanced Space Technologies for Robotics and Automation 'ASTRA 2002' ESTEC, Noordwijk, The Netherlands, November 19-21, 2002 Kinematics Example

5 Control architecture 4-th order joint state feedback: qm, dqm, τ, dτ Joint level Position k maximpedance k 0 Torque control control control 3kHz stiff robot dynamics inverse kinematics serial bus 1kHz Impedance control adaptive gain adjustment Force control motor position joint torque link position cartesian level Force-torque sensor

6 Modifications Towards Free Space Application "Joint arrangement modified from an inline arrangement to an offset arrangement. "For ROKVISS PCBs are mounted into separate circular aluminum housings and shedded afterwards. "Input current observing to prevent destruction due to single event latch-ups.

7 ROKVISS Components "ROKVISS will be installed at the Russian Service Module (SM). "It consists of a small 2-joints robot, mounted on a Universal Workplate (UWP), a controller, a stereo camera, an illumination system, a power supply, and a mechanical contour device to verify the robot's functions and performance.

8 ROKVISS Robotic System Joint 2 Stereo camera & illumination Experiment contour Stylus Joint 1

9 Operational Modes "ROKVISS will be operated in the tele-presence mode while the ISS is in direct (S-band) radio contact with the German tracking station in Weilheim. "Robot tasks are executed in autonomous mode to verify and identify joint parameters during non contact phases. The joint parameters are stored on-board and downlinked on demand during the next possible radio contact phase. "All experiments will be repeated several times during the entire mission to yield comparable sets of data.

10 Tele-Presence Mode for ROKVISS " For the most space robotics applications in the field of servicing and maintenance, the direct inclusion of an human operator into the control loop is inevitable, because such missions couldn t be prepared in detail off-line on-ground. " It opens up a much broader range of applications for telerobotic systems, because the operator can apply his skills on the remote site, almost as if he would be currently present there. " ROKVISS provides a good means to evaluate and demonstrate the capability of the tele-presence mode in a realistic space mission scenario.

11 Tele-Presence Mode for ROKVISS "Tele-presence demands a low signal round trip time, high sampling frequency and a neglectable jitter. Round trip < 500 ms Ground <-> LEO ~ 2 ms Ground <-> GEO ~ 240 ms Ground <-> LEO via relay in GEO ~ 480 ms Sampling rate 2 ms min Jitter < 50% of sampling rate

12 ROKVISS Experiments " Tele-Presence Mode Experiments " Peg-in-hole " Contour-following " Virtual-spring " Real-spring " Experiments with simulated increased round trip time " Automatic Mode Experiments " Experiments for the identification of the joint dynamics parameters for controller design " Experiments for impedance control " Contact Dynamics Experiment (CSA) " Public Outreach Experiments " It is planned to take photos of the ISS, incoming and outgoing spacecraft, and the extravehicular activities of the astronauts.