Bernhard Brunner

Sensor-based space robotics-ROTEX and its telerobotic features

In early 1993 the space robot technology experiment ROTEX was flown with space-shuttle Columbia. A multisensory robot onboard the spacecraft successfully worked in autonomous modes, teleoperated by astronauts, as well as in different telerobotic ground control modes. These included online teleoperational and telesensor-programming: a task-level oriented programming technique involving learning-by-showing concepts in a virtual environment. The robots key features were its multisensory gripper and the local sensory feedback schemes that are the basis for shared autonomy. The corresponding man-machine interface concepts, which use a six-degree-of-freedom non-force-reflecting control ball and visual feedback to the human operator, are explained. Stereographic simulation on the ground was used to predict not only the robots free motion but even the sensor-based path refinement onboard. Prototype tasks performed by this space robot were the assembly of a truss structure, connecting/disconnecting an electrical plug (orbit replaceable unit exchange), and grasping free-floating objects. >

A Humanoid Two-Arm System for Dexterous Manipulation

This paper presents a humanoid two-arm system developed as a research platform for studying dexterous two-handed manipulation. The system is based on the modular DLR-Lightweight-Robot-III and the DLR-Hand-II. Two arms and hands are combined with a three degrees-of-freedom movable torso and a visual system to form a complete humanoid upper body. In this paper we present the design considerations and give an overview of the different sub-systems. Then, we describe the requirements on the software architecture. Moreover, the applied control methods for two-armed manipulation and the vision algorithms used for scene analysis are discussed

ROTEX-the first remotely controlled robot in space

In April 1993 for the first time in the history of space flight, a small multisensory robot performed a number of prototype tasks on-board a spacecraft (spacelab D2 on shuttle COLUMBIA) in different operational modes that are feasible today, namely preprogrammed remotely controlled operations by the astronauts using a control ball and a stereo TV-monitor, as well as remotely controlled from ground via the human operator and 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. Several key technologies have made this space robot technology experiment ROTEX a big success: multisensory gripper technology, local (shared autonomy) sensory feedback control concepts, and the powerful delay-compensating 3D-graphics simulation (predictive simulation) in the telerobotic ground station. This paper focusses on the tele-sensor-programming approach and the predictive simulation used for remote ground control.<<ETX>>

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.

A humanoid upper body system for two-handed manipulation

This video presents a humanoid two-arm system developed as a research platform for studying dexterous two-handed manipulation. The system is based on the modular DLR-Lightweight-Robot-III and the DLR-Hand-II. Two arms and hands are combined with a three degrees-of-freedom movable torso and a visual system to form a complete humanoid upper body. The diversity of the system is demonstrated by showing the mechanical design, several control concepts, the application of rapid prototyping and hardware-in-the-loop (HIL) development as well as two-handed manipulation experiments and the integration of path planning capabilities.

Space Robotics—DLR's Telerobotic Concepts, Lightweight Arms and Articulated Hands

The paper briefly outlines DLRs experience with real space robot missions (ROTEX and ETS VII). It then discusses forthcoming projects, e.g., free-flying systems in low or geostationary orbit and robot systems around the space station ISS, where the telerobotic system MARCO might represent a common baseline. Finally it describes our efforts in developing a new generation of “mechatronic” ultra-light weight arms with multifingered hands. The third arm generation is operable now (approaching present-day technical limits). In a similar way DLRs four-fingered hand II was a big step towards higher reliability and yet better performance. Artificial robonauts for space are a central goal now for the Europeans as well as for NASA, and the first verification tests of DLRs joint components are supposed to fly already end of 93 on the space station.

Advances in Robotics: The DLR Experience:

Key items in the development of a new smart robot generation are explained in light of DLR’s recent activities in robotics research. These items are the design of articulated hands, ultra-lightweight links, and joint drive systems with integrated joint torque control, sensory feedback including real-time 3-D vision, learning and skill-transfer, modeling the environment using sensorfusion, and new sensor-based off-line programming techniques based on teaching by showing in a virtual environment.

Advances in orbital robotics

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.

Task directed programming of sensor based robots

We propose the so-called TeleSensor programming concept that uses sensory perception to achieve local autonomy in robotic manipulation. Sensor based robot tasks are used to define elemental moves within a high level programming environment. This approach is applicable in both, the real robots world and the simulated one. Beside the graphical off-line programming concept, the range of application lies especially in the field of teleoperation with large time delays. A shared autonomy concept is proposed that distributes intelligence between man and machine. The feasibility of graphically simulating the robot within its environment is extended by emulating different sensor functions to achieve a correct copy of the real system behaviour as far as possible. The programming paradigm is supported by a sophisticated graphical man machine interface. Sensor fusion aspects with respect to autonomous sensor controlled task execution are discussed as well as the interaction between the real and the simulated system.<<ETX>>

A Sensor-based Telerobotic System for the Space Robot Experiment ROTEX

The space robot technology experiment ROTEX to fly with the next spacelab mission D2 in 1993 provides a sensor-controlled robot which is supposed to work in an autonomous mode, teleoperated by astronauts, and teleoperated from ground. The robots key features are its multisensory gripper and the local („shared”) sensory feedback schemes. The corresponding man-machine interface concepts using a 6 dof control ball and visual feedback to the human operator are explained. Sensory simulation on ground using advanced stereo graphics is supposed to predict 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 grasped. The telesensorprogramming concept is explained as well as the learning schemes involved.