Gerhard Grunwald

Feature-based visual servoing and its application to telerobotics

Advances in visual servoing theory and practice now make it possible to accurately and robustly position a robot manipulator relative to a target. Both the vision and control algorithms are extremely simple, however they must be initialized on task-relevant features in order to be applied. Consequently, they are particularly well-suited to telerobotics systems where an operator can initialize the system but round-trip delay prohibits direct operator feedback during motion. This paper describes the basic theory behind feature-based visual servoing, and discusses the issues involved in integrating visual servoing into the ROTEX space teleoperation 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.

Toward task-directed planning of cooperating sensors

Recently, there has been increased emphasis on employing reactive actions in robot task planning. The principle reasons for this change are to increase the robustness of robot action by making them sensor controlled, and to accommodate dynamic, unpredictable environments. However, in many cases, supporting reactive mechanisms requires choosing sensor inputs for the reactive procedure. This paper addresses the issue of planning the sensor required to carry out a reactive robot program. A preliminary framework for planning is presented, and sensor planning is illustrated for the problem of replacing a mechanically attached plug in a space environment.

Observation and Execution

Assistive robotic systems in household or industrial production environments get more and more capable of performing also complex tasks which previously only humans were able to do. As robots are often equipped with two arms and hands, similar manipulations can be executed. The robust programming of such devices with a very large number of degrees of freedom (DOFs) compared with single industrial robot arms however is laborious if done joint-wise. Two major directions to overcome this problem have been previously proposed. The programming by demonstration (PbD) approach, where human arm and recently also hand motions are tracked, segmented and re-executed in an adaptive way on the robotic system and the high-level planning approach which tries to generate a task sequence on a logical level and attributes geometric information as necessary to generate artificial trajectories to solve the task. Here we propose to combine the best of both worlds. For the very complex motion generation for a robotic hand, a rather direct approach to assign manipulation actions from human demonstration to a human hand is taken. For the combination of different basic manipulation actions the task constraints are segmented from the demonstration action and used to generate a task oriented plan. This plan is validated against the robot kinematic and geometric constraints and then a geometric motion planner can generate the necessary robot motions to fulfill the task execution on the system.

Aus der Forschung zum Industrieprodukt: Die Entwicklung des KUKA Leichtbauroboters

Zusammenfassung Forschungsergebnisse in marktfähige Produkte zu verwandeln erfordert ein beträchtliches Maß an Ausdauer und starkes Unternehmertum. Der KUKA Leichtbauroboter (LBR) ist das jüngste Ergebnis einer langjährigen Forschungs- und Entwicklungskooperation zwischen der KUKA Roboter GmbH in Augsburg und dem Institut für Robotik und Mechatronik des DLR in Oberpfaffenhofen. Dieser Beitrag schildert den Weg der Produktentstehung, den innovativen Charakter des LBR und zeigt erste Anwendungsbeispiele. Abstract Transforming research results into marketable products requires considerable endurance and a strong sense of entrepreneurship. The KUKA lightweight robot (LWR) is the latest outcome of a bilateral research collaboration between KUKA Roboter, Augsburg, and the Institute of Robotics and Mechatronics at the German Aerospace Center (DLR), Oberpfaffenhofen. The stages of product genesis, the most innovative features and first application examples are presented.

Task-Directed Sensor-Planning

Recently, there has been increased emphasis on employing reactive actions in robot task planning. The principle reasons for this change are to increase the robustness of robot actions by making them sensor controlled, and to accommodate dynamic, unpredictable environments. However, in many cases, supporting reactive mechanisms requires choosing sensor inputs for the reactive procedure. This paper addresses the issue of planning the sensing and fusion required to carry out a reactive robot program. A preliminary framework for planning and fusion is presented, and sensor planning is illustrated for the problem of replacing a mechanically attached plug in a space environment.