Despite the progress since the first attempts of mankind to explore space, it appears that sending man in space remains challenging. While robotic systems are not yet ready to replace human presence, they provide an excellent support for astronauts during maintenance and hazardous tasks. This paper presents the development of a space qualified multi-fingered robotic hand and highlights the most interesting challenges. The design concept, the mechanical structure, the electronics architecture and the control system are presented throughout this overview paper.

ROKVISS, the German new space robotics technology experiment, was successfully installed outside at the Russian Service Module of the International Space Station (ISS) during an extravehicular space walk at the end of January 2005. Since February 2005 a two joint manipulator can be operated from ground via a direct radio link. The aim of ROKVISS is the in flight verification of highly integrated modular robotic joints as well as the demonstration of different control modes, reaching from high system autonomy to force feedback teleoperation. A main goal of the experiment is the evaluation of the dynamical parameters (especially friction, motor constant and stiffness), as well as the monitoring of their evolution over the duration of the mission, in order to validate the long term performance of the system. The paper gives first a short overview of the experiment and in particular a description of the applied control structures. The main focus of the paper is on the joint parameter identification results obtained so far, during one year of operation

The increasing number of launched satellites per year, calls for solutions to keep free operational space for telecommunication systems in geo-synchronized orbit, as well as to avoid the endangering of space systems in LEO (low-Earth orbit) and of the public living in the habited parts on Earth. Examples for such dangerous stranded space systems in the past are Skylab and MIR. In the future, the uncontrolled and accidental de-orbiting of other huge satellites is expected, where parts of these will hit the surface of the Earth. A feasible way to handle such problems might be to enforce the operational requirement to use some dedicated residual fuel for a controlled de-orbiting, or in case of GEO (geostationary orbit), to lift the satellites at their end of life into the graveyard orbit. Despite these measures, malfunctions of solar generators, control systems or thrusters cannot be avoided. Therefore, on-orbit servicing (OOS) will be a mandatory and challenging topic for space robotics in the near future. The outcome of national German projects like ROTEX, ESS and GETEX/ETS-VII represent a know-how which can be directly applied for the development of OOS-robotic systems. Control structures and several possible operational modes are discussed within this paper. The recently started national project ROKVISS already provides the necessary space-qualified hardware as well as the very powerful telepresence operational mode. The paper will concentrate on a description of the ROKVISS mission

ROKVISS, Germany's newest space robotics technology experiment, was successfully installed outside at the Russian Service Module of the International Space Station (ISS) during an extravehicular space walk at the end of January 2005. Since February 2005 a two joint manipulator is operated from ground via a direct radio link. The aim of ROKVISS is the in flight verification of highly integrated modular robotic joints as well as the demonstration of different control modes, reaching from high system autonomy to force feedback teleoperation (telepresence mode). The experiment will be operated for at least one year in free space to evaluate and qualify intelligent light weight robotics components under realistic circumstances for maintenance and repair tasks as foreseen in upcoming manned and unmanned space applications in near future. This paper focuses in the telepresence control mode, its technology and first results from the space experiment ROKVISS

Outlines the situation in orbital space robotics with special reference to what DLR (German Aerospace Center) has contributed to the field. After our ROTEX experiment, the first remotely controlled space robot inside the space shuttle, the Japanese ETS VII has now been the first remotely controlled free-flying space robot. We had the opportunity to control this arm from the ground, too, including the use of the robot arm as a satellite attitude controller. It is outlined how it is now time to take the next steps towards operational ground-controlled space robot systems, presumably first on the International Space Station, but later on as free flying robonauts assisting or even replacing extra vehicular activities.

This paper presents detailed description of a laboratory simulator that uses two robots fixed on earth to simulate the motion of a robot in space relative to a free-flying target. This simulator is appealing because it creates an environment on earth similar to what an astronaut observes watching from the space shuttle. Therefore, it could be a valuable tool for training of astronauts on earth. Also, this simulator uses off-the-shelf industrial robots in contrast to laboratory facilities today that use special designs of robots to achieve this same task. The proposed simulator can be valuable for studying real-time motion in space and in evaluating the effectiveness of onboard sensors and control systems. The objectives of this paper are to: i) describe the laboratory setup, ii) present the computational details of this simulator, iii) estimate the computation needs of this simulator, and iv) present a computer implementation of this simulator using two KUKA robots.

The paper discusses delay-compensating techniques when operating a space robot from ground or from a another remote spacecraft. These kind of techniques have been a key element in the space robot technology experiment ROTEX that has successfully flown with shuttle COLUMBIA end of April 93. During this "spacelab-D2"-mission for the first time in the history of space flight a small, multisensory robot (i.e. provided with modest local intelligence) has performed prototype tasks on board a spacecraft in different operational modes, namely preprogrammed (and reprogrammed from ground), remotely controlled (teleoperated) by the astronauts, but also remotely controlled from ground via the human operator as well as via machine intelligence. In these operational modes the robot successfully closed and opened connector plugs (bayonet closure), assembled structures from single parts and captured a free-floating object. This paper focuses on the powerful delay-compensating 3D-graphics simulation (predictive simulation) concepts that were realized in the telerobotic ground station and which allowed the authors to compensate delays of up to 7 sec e.g. when grasping the floating object fully automatically from ground.>

Outlines key technologies in the approach of the author's research establishment to space robotics. Based on multisensory gripper technology, local on-board sensory feedback, and predictive graphic simulation (with emphasis on sensory simulation) a tele-sensor programming concept is introduced that allows sensor-based teleoperation in spite of large signal delays as well as sensor-based off-line programming following a "learning by showing" concept. A small multisensory robot based on these concepts has flown in space with a ten-day Space Shuttle mission. This robot technology experiment ROTEX was very successful and showed that, with these sensor-based concepts, even present-day space robots can perform different prototype tasks in a variety of operational modes, including automatic (reprogrammable) operation, and on-board teleoperation using human and/or machine intelligence.

The space robot technology experiment ROTEX to fly with the next spacelab mission D2 in January 1993 provides a multisensory robot which is supposed to work in an autonomous mode, teleoperated by astronauts, as well as in different telerobotic ground control modes.These include on-line teleoperation and telesensorprogramming, a task-level oriented programming technique involving `learning by showing'concepts in a virtual environment. The robot's key features are its multisensory gripper and the local sensory feedback schemes which are the basis for shared autonomy. The corresponding man-machine interface concepts using a 6 dof non- force-reflecting control ball and visual feedback to the human operator are explained.Stereographic simulation on ground is supposed to predict even the sensor based path refinement on board, while realtime fusion of stereo images and laser range information helps to predict the motion of floating objects to be grapsed from ground, too. Other prototype tasks to be performed by this space robot are the assembly of a truss structure and connecting/ disconnecting an electrical plug (orbit replaceable unit exchange ORU).

The problems that arise when sensor-controlled robots in space are teleoperated from ground stations are discussed. A supervisory control concept is described that makes it possible to realize shared control between teleoperator and sensor-controlled robot in a variety of configurations. Predictive 3D computer graphics currently seems to be the only way to cope successfully with the problem of transmission-time delays of several seconds. Appropriate estimation schemes in combination with knowledge-based world modeling are outlined, which include models of the delay lines, the robot, moving objects, etc., and which derive the necessary updates from sensory data as they are sent down from the spacecraft to earth (e.g. via real-time stereo vision). The space robot technology experiment Rotex scheduled for the next German Spacelab mission (2D) is taken as a basis for the problem description.>

A concept for sensory feedback and sensor-based teach-in in robotics is presented. Based on previous work of different authors a scheme of hybrid sensory-position control is proposed and has been realized that interpretes every "rudimentary" teach command in terms of sensory interaction with the environment by generating the socalled "artificial constraints" and the refined path automatically. Robots with arbitrarily programmable stiffness are one outcome of our technique. Motion commands and sensor data are stored together. The latter ones are then available as reference values for the repetition mode in a possibly changing environment. It is shown that by introducing pseudo-forces/torques the proposed techniques are equally applicable to different kinds of sensor, as are force-torque-sensors, range finders or inductive sensors. The "sensor-ball"-technique as developed at DFVLR is discussed as one physical realization. Operational systems of this kind, first tested with an ASEA robot in our lab, are going into industrial application now.