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Chapter 55 — Space Robotics

Kazuya Yoshida, Brian Wilcox, Gerd Hirzinger and Roberto Lampariello

In the space community, any unmanned spacecraft can be called a robotic spacecraft. However, Space Robots are considered to be more capable devices that can facilitate manipulation, assembling, or servicing functions in orbit as assistants to astronauts, or to extend the areas and abilities of exploration on remote planets as surrogates for human explorers.

In this chapter, a concise digest of the historical overview and technical advances of two distinct types of space robotic systems, orbital robots and surface robots, is provided. In particular, Sect. 55.1 describes orbital robots, and Sect. 55.2 describes surface robots. In Sect. 55.3, the mathematical modeling of the dynamics and control using reference equations are discussed. Finally, advanced topics for future space exploration missions are addressed in Sect. 55.4.

DLR ROTEX: The first remotely-controlled space robot

Author  Gerd Hirzinger, Klaus Landzettel

Video ID : 330

Remotely-controlled space robot ROTEX in the Spacelab D2 mission flown with Shuttle Columbia in April 1993. Among the highlights of the experiment were the verification of shared autonomy when opening a bayonet closure and the fully autonomous grasping of a free-flying object with 6 s round-trip delay.

DLR predictive simulation compensating 6-second round-trip delay

Author  Gerd Hirzinger, Klaus Landzettel

Video ID : 331

This brief video shows results of the ROTEX experiment on the fully automatic grasping of a small free-floating cube with flattened edges by the ground computers which evaluated the stereo images from the robot gripper, estimated the motion, predicted it for the 6 s communication round-trip delay, and sent up the commands for grasping. In the view are the results of predictive simulation (right-hand side) and the delayed true-camera measurements (left-hand side).

DLR GETEX manipulation experiments on ETS-VII

Author  Gerd Hirzinger, Klaus Landzettel

Video ID : 332

This is a video record of the remote control of the first free-flying space robot ETS-VII from the DLR ground control station in Tsukuba, done in close cooperation with Japan’s NASDA (today’s JAXA). The video shows a visual-servoing task in which the robot moves autonomously to a reference position defined by visual markers placed on the experimental task board. In view are the true camera measurements (top left, end-effector camera; top right, side camera), the control room in the ground control station (bottom left), and the robot simulation environment (bottom right), which was used as a predictive simulation tool.

DLR ROKVISS animation

Author  Gerd Hirzinger, Klaus Landzettel

Video ID : 333

ROKVISS: animated simulation of a two-joint, torque- controlled manipulator on the ISS as it performs an iInspection task. The split screen shows simulated views of the robot (at top) and the stereo camera's view of the robot end-effector (at bottom).

DLR ROKVISS camera images pulling spring

Author  Gerd Hirzinger, Klaus Landzettel

Video ID : 334

ROKVISS manipulating the handles of springs to verify the long-term performance of the torque-controlled joints. The stereo-camera view from an actual robot end-effector is shown. At first, the robot performs an inspection maneuver. Then, it pulls on the spring in the experimental task board, with two different oscillation frequencies, to gain measurement data on the robot-joint's parameters (stiffness, temperature-dependent friction, etc.).

DLR ROKVISS disassembly

Author  Gerd Hirzinger, Klaus Landzettel

Video ID : 336

This video shows the disassembly of the ROKVISS robot from the ISS by Russian cosmonauts who brought the manipulator back to the DLR at the end of its mission in 2011. It was indeed very valuable to be able to analyze the robot on the ground, after it had spent seven years in space.

DLR telepresence demo of removal of a cover

Author  Jordi Artigas, Gerd Hirzinger

Video ID : 337

Telepresence with force reflection using DLR’s light-weight robots as teleoperator-input devices.

DLR telepresence demo with time delay

Author  Jordi Artigas, Gerd Hirzinger

Video ID : 338

Video demonstration of the behavior of telepresence with force reflection up to 500 ms round-trip delay.

DLR DEOS demonstration mission simulation

Author  Roberto Lampariello, Gerd Hirzinger

Video ID : 339

This video simulation shows an intended task in DLR's DEOS project for grasping an uncooperative, tumbling target satellite (left) by means of a free-flying robot (right, servicer satellite and robot manipulator). The task consists of approaching a predefined point on the target with the robot end-effector, tracking the same point with the robot end-effector while homing in onto it, closing the grasp, and stabilizing the relative motion between the two spacecraft. Following this, the robot performs a berthing task to secure the target in a dedicated docking port on the servicer. The servicer's GNC system is switched off during the entire duration of the grasping maneuver, giving rise to free-floating dynamic behavior of the manipulator. The complete robot trajectory is provided by a motion planner in order to guarantee feasibility with respect to motion constraints, such as the the field of view of the end-effector camera, etc.