Author name cluster

Ralf Koeppe

Possible papers associated with this exact author name in Arrow. This page groups case-insensitive exact name matches and is not a full identity disambiguation profile.

10 papers

1 author row

IROS Conference 2006 Conference Paper

Reactionless Control for two Manipulators Mounted on a Cable-Suspended Platform

Roberto Lampariello
Johann Heindl
Ralf Koeppe
Gerhard Hirzinger

The dynamics and control of a cable-suspended, two-arm robotic system are developed for an entertainment application. One manipulator arm is controlled to fulfil a user defined task. The second arm is then controlled to compensate for the disturbances on the cable-suspended platform arising from the motion of the first. Model-based feedforward control, stemming from the momentum conservation equations of a free-floating robot, is developed for the motion compensation problem. Furthermore, due to model uncertainty, sensor-based feedback control is introduced, to account for undesired oscillatory motions of the system. The latter control problem reduces to the dissipation of the oscillatory energy of the system, by means of adequate robot control. Both control methods are implemented and tested on an experimental set-up

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IROS Conference 2002 Conference Paper

Data fusion for compliant motion tasks based on human skills

Rui Cortesão
Ralf Koeppe
Urbano J. Nunes
Gerhard Hirzinger

The paper discusses new developments of the data fusion paradigm due to Cortesao and Koeppe (1999, 2000). A bank of Kalman filters is analyzed in the fusion process. Experiments for a robotic compliant motion task (peg-in-hole) emerged from human skills are reported. Stereo vision and pose sense are fused to execute the task. Feedforward artificial neural networks (ANNs) are trained to transfer human skills to robotic manipulators.

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IROS Conference 2001 Conference Paper

Compliant motion control with stochastic active observers

Rui Cortesão
Ralf Koeppe
Urbano J. Nunes
Gerhard Hirzinger

The theory of active observers was initially described by Cortesao et al. (2000). This paper introduces properties of the Kalman gains used in the active observer (AOB) design. An important result of the state-space design is demonstrated, which allows stiffness adaptation without changing the control structure. Experiments with a human-robot skill transfer system to perform the peg-in-hole compliant motion task are described, showing the importance of the AOB.

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IROS Conference 2000 Conference Paper

A signal-based approach to localization and navigation of autonomous compliant motion

Ralf Koeppe
Gerhard Hirzinger

Architectures for the execution of autonomous compliant motion (ACM) require modules for 6 degree-of-freedom localization, navigation and force control of robot manipulators. We review existing model- and signal-based approaches to ACM and present a solution for the synthesis of localization and navigation using sensorimotor signals recorded from human demonstration.

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IROS Conference 2000 Conference Paper

Explicit force control for manipulators with active observers

Rui Cortesão
Ralf Koeppe
Urbano J. Nunes
Gerhard Hirzinger

The article describes a systematic procedure to design a force controller with active observers (AOB). The design is based on pole placement using discrete state space theory. The concept of AOB is introduced as a starting point to perform robust estimates of the system state. The robustness of the system is accomplished through optimal noise processing embedded in the control strategy. The design was tested as a force controller in a Manutec R2 Robot at the DLR.

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IROS Conference 2000 Conference Paper

Verification of an advanced space teleoperation system using Internet

Yuichi Tsumaki
Toshihiko Goshozono
Koyu Abe
Masaru Uchiyama
Ralf Koeppe
Gerhard Hirzinger

In our previous work, several system elements for space teleoperation were introduced: a Singularity Consistent (SC) teleoperation system, a mixed force and motion commands based space teleoperation system, and a 6-DOF haptic interface (Y. Tsumaki and M. Uchiyama, 1997; Y. Tsumaki et al. , 1998). We introduce an advanced space teleoperation system which includes all the above elements. As a result, the system realizes safety against the singularities and excessive force, with good perception for the operator. In addition, to verify the effectiveness of this system, we conducted experiments through the Internet between DLR in Germany and Tohoku University in Japan in January 1999.

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IROS Conference 1999 Conference Paper

Sensor fusion for skill transfer systems

Rui Cortesão
Ralf Koeppe

Describes how to design a data fusion module for skill transfer purposes. The data fusion paradigm is addressed. It consists of two independent modules for optimal fusion and filtering. A new interpretation of the Kalman filter equations is done, to achieve a "model-free" equation capable of following arbitrary variables. An engineering approach is used to tune the parameters of interest for a certain task. The fusion algorithm presented is global, and could easily be extended to any arbitrary system. It was successfully tested in the Institute of Robotics and System Dynamics at the DLR.

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IROS Conference 1999 Conference Paper

Sensorimotor compliant motion from geometric perception

Ralf Koeppe
Gerhard Hirzinger

Most of the approaches proposed in the field of sensor based assembly use force and velocity, i. e. , sensor signals representing dynamics, as a base on which a desired compliant motion strategy is specified. In contrast, especially while performing alignment and insertion tasks the problem of sensing the assembly state of two objects w. r. t. each other is of geometric nature. Using a generic sensorimotor skill model for compliant motion tasks we discuss the difference between dynamic and geometric perception. We propose approaches of kinesthetic and visual sensing and show the robustness of compliant motion skill maps obtained from sensor signals representing the task geometry rather than the task dynamics.

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IROS Conference 1997 Conference Paper

Dynamic manipulability analysis of compliant motion

Ralf Koeppe
Tsueno Yoshikawa

Compliant motion tasks can be programmed by human demonstration without the use of the actual robot system. In space applications and sensor off-line programming systems the task is planned and programmed in a virtual reality environment which simulates the world model of the task to be performed. Furthermore, in industrial and service applications teaching devices measuring the force and motion of the human hand allow the operator to demonstrate a task in a very natural way. By using dynamic manipulability analysis of motion and force, we investigate if a compliant motion trajectory obtained by the above described demonstration processes can be executed on a given robot. We analyze the maximum task workspace of executability, the optimal robot-task configuration and the range of necessary or possible scaling factors for motion and forces. The approach is demonstrated using a numerical example.

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IROS Conference 1996 Conference Paper

Skill representation and acquisition of compliant motions using a teach device

Ralf Koeppe
Achim Breidenbach
Gerhard Hirzinger

We are proposing a supervised learning approach in robot force control which enables robot programming by human demonstration. To demonstrate the task in an intuitive way, we designed a teach device which acquires the sensorimotion of the human. The design and use of the teaching device for skill acquisition is discussed. Recording of compliant motion, of the human is shown for the "put block in a corner of a box problem" and the "peg in hole problem". Skill representation is demonstrated for the first of the two problems. Finally we are describing other useful applications of the teach device in the field of world modeling and robotics.

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