Detlef Reintsema

DLR's robotics technologies for on-orbit servicing

The paper outlines the long-term space robotics projects as well as recent results in DLRs robotics laboratory. The driving force behind all the efforts made in hardware and software development is to design highly integrated robot systems which can be utilized in space, especially for extravehicular activities. Our envisaged field of application reaches from servicing satellites in low Earth and geostationary orbit to space stations as well as planetary exploration robots, all of them fully ground controlled from Earth. The ground control concept is based on the MARCO architecture, which was verified in a few space robotics projects over recent years. It includes taskoriented programming capabilities for autonomous robot control at the remote site as well as methods for direct telemanipulation by means of virtual reality and telepresence techniques, which allows a realistic feeling for the ground operator via visual and haptic feedback devices. In addition to the control techniques, a new generation of ultra-lightweight robot arms with articulated hands is required to give the space robot systems the necessary dexterity. A number of experiments will verify and consolidate the usage of space robots. First, the ROKVISS experiment aims at the verification of DLRs lightweight robotics components under realistic mission conditions. Second, the TECSAS experiment will show the feasibility of autonomous as well as telepresence methods for further satellite servicing tasks. Third, a strong cooperation with industry will create the first business case in on-orbit-servicing: by attaching a tugboat to a satellite, whose propellant is declining, the lifetime of valuable telecommunication satellites could be prolonged for several years.

Robotic On-Orbit Servicing - DLR's Experience and Perspective

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

Robot Assisted Force Feedback Surgery

Minimally invasive surgery characterizes a sophisticated operation technique in which long, slender instruments are inserted into the patient through small incisions. Though providing crucial benefits compared to open surgery (i.e. reduced tissue traumatization) it is also faced with a number of disadvantages. One of the major problems is that the surgeon cannot access the operating field directly and, therefore, can neither palpate tissue nor sense forces sufficiently. Furthermore, the dexterity of the surgeon is reduced as the instruments have to be pivoted around an invariant point.

DLR’s Advanced Telerobotic Concepts and Experiments for On-Orbit Servicing

Space robotics will become a key technology for the exploration of outer space and the operation and maintenance of space stations, satellites and other platforms, saving costs and relieving man from dangerous tasks. But we do not have to wait until robots are really autonomous or intelligent, since by modern teleoperation and telepresence we are able to remotely control robot systems from the ground in the sense of “prolonging man’s arm into space”. Humans, with their several hundred thousand years of evolution, will not adapt themselves to the hostile space environment, whilst robots, which have only been developed for just over 40 years, can be much more easily adapted to such an environment. As presented within this work, few pioneering telerobotic experiments like ROTEX, the first remotely controlled space robot system, ETS-VII, the first free-floating space robot experiment, or ROKVISS, Germany’s recent advanced space robot experiment on the International Space Station, have been proposed and conducted on the way towards a space robot assistant system for the usage as an artificial astronaut to perform On-Orbit Servicing (OOS) tasks.

Robotics Component Verification on ISS ROKVISS - Preliminary Results for Telepresence

ROKVISS, Germanys 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

Toward high-fidelity telepresence in space and surgery robotics

High-fidelity telepresence is considered to be a key subject for the development of advanced space and surgery robotic systems. The emphasis of this paper are the key challenges like multimodal data servicing, bilateral and shared control concepts, and kinesthetic feedback devices. These technologies are the basic principles in the development of advanced space and surgery applications. Beside these technologies, advanced mechatronic systems are required as shown within this paper. The applicability of the high-fidelity telepresence concept is explored by selected space and surgery scenarios.

Flexible multimodal telepresent assembly using a generic interconnection framework

A multimodal Internet-based telepresence system with interactive stereo vision, additional photo-realistic predictive display, and kinesthetic bilateral coupling in three degrees of freedom is presented. For easy coupling of various telepresence components by a unified interface structure and a generic link management protocol a CORBA based interconnection framework has been developed. By solving a peg-in-hole task in an industrial environment and with varying communication delay times, the system provides all capabilities for multimodal telepresent remote maintenance and assembly.

DIMSART: A REAL TIME - DEVICE INDEPENDENT MODULAR SOFTWARE ARCHITECTURE FOR ROBOTIC AND TELEROBOTIC APPLICATIONS

In this paper a software architecture for robotic and telerobotic applications will be described. The software is device and platform independent, and is distributed control orientated. Thus, the package is suitable for any real time system configuration. The architecture allows designers to easily build complex control schemes for any hardware device, easily control and manage them, and communicate with other devices with a plug- in/plug-out modular concept. The need to create a platform where control engineers/designers could freely implement their algorithms, without needing to worry about the device driver and programming related issues, further motivated this project. Implementing a new control algorithm with the software architecture described here, requires that the designer simply follow a template where the necessary code is reduced to only those functions having to do with the controller. We conducted several teleoperation schemes, one of which will be presented here as a configuration example.