Author name cluster

Markus Grebenstein

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19 papers

1 author row

IROS Conference 2018 Conference Paper

CLASH: Compliant Low Cost Antagonistic Servo Hands

Werner Friedl
Hannes Höppner
Florian Schmidt 0001
Máximo A. Roa
Markus Grebenstein

This paper presents the first two members of the new generation of CLASH hands, which exploit low cost actuation and rapid prototyping to create antagonistic modular and lightweight hands and grippers. The hands approach the robustness of the DLR Awiwi hand with a much lower complexity and cost. To reduce the number of required actuators, a differential coupling mechanism for underactuated fingers was developed, along with a new mechanism that uses variable stiffness actuation in order to increase the workspace of underactuated fingers. The hands provide a research platform for both hand-in-hand and robotic grasping. Design aspects are discussed, and an initial experimental validation verifies the hands' performance.

IROS Conference 2015 Conference Paper

Two-dimensional orthoglide mechanism for revealing areflexive human arm mechanical properties

Hannes Höppner
Markus Grebenstein
Patrick van der Smagt

The most accurate and dependable approach to the in-vivo identification of human limb stiffness is by position perturbation. Moving the limb over a small distance and measuring the effective force gives, when states are steady, direct information about said stiffness. However, existing manipulandi are comparatively slow and/or not very stiff, such that a lumped stiffness is measured. This lumped stiffness includes the limb response during or after reflexes influenced by both, the passive musculotendon and active neuronal component. As this approach usually leads to inconsistencies between the data and the stiffness model, we argue in favour of fast, pre-reflex impedance measurements-i. e. , completing the perturbation movement and collecting the data before effects of spinal reflexes or even from the motor cortex can influence the measurements. To obtain such fast planar movements, we constructed a dedicated orthoglide robot while focusing on a lightweight and stiff design. Our subject study of a force task with this device lead to very clean data with always positive definite Cartesian stiffness matrices. By representing them as ellipses, we found them to be substantially bigger in comparison to standard literature which we address to a larger number of recruited motor units. While ellipses orientation and the length of their main axis increased, the shape decreased with the exerted force. The device will be used to derive design criteria for variable-stiffness robots, and to investigate the relation between muscular activity and areflexive joint stiffness for teleoperational approaches.

ICRA Conference 2014 Conference Paper

Guiding effects and friction modeling for tendon driven systems

Jens Reinecke
Maxime Chalon
Werner Friedl
Markus Grebenstein

This paper discusses tendon friction effects regarding guiding and material selection. In order to extract valuable information for designers of tendon driven systems, several experiments are conducted to investigate e. g. the intrinsic friction or sliding effect. The results are used to build an experimental friction model and to derive a set of guidelines. The mechanical designer can use the proposed models to anticipate the friction for a given tendon path. Additionally, the guidelines help the mechanical designer to systematically verify the numerous constraints involved in the design process of a tendon driven system.

IROS Conference 2012 Conference Paper

Intrinsically elastic robots: The key to human like performance

Sami Haddadin
Felix Huber
Kai Krieger
Roman Weitschat
Alin Albu-Schäffer
Sebastian Wolf 0001
Werner Friedl
Markus Grebenstein

Intrinsically elastic robots, which technically implement some key characteristics of the human muskoskeletal system, have become a major research topic in nowadays robotics. These novel devices open up entirely new control approaches. They base on temporary storage of potential energy and its timed transformation into kinetic energy. In legged locomotion, such considerations have been a common tool for unveiling the respective fundamental physical processes. However, in arm control, elasticities were typically considered parasitic. In this video we outline our efforts in exploiting the inherent capabilities of intrinsically elastic robots in order to bring them closer to human performance. Instead of applying purely kinematic learing-by-demonstration approaches, which are certainly suboptimal, we argue for using model based techniques in order to optimally exploit the system dynamics such that highly dynamic motion and manipulation capabilities can be achieved. In particular, the explicit use of elasticities as temporary energy tanks can be fully exploited, if they are modeled adequately as an integral part of the mechanism. We also believe that such approaches can substantially contribute to the understanding of human motion biomechanics.

IROS Conference 2012 Conference Paper

Variable impedance actuators: Moving the robots of tomorrow

Bram Vanderborght
Alin Albu-Schäffer
Antonio Bicchi
Etienne Burdet
Darwin G. Caldwell
Raffaella Carloni
Manuel G. Catalano
Gowrishankar Ganesh

Most of today's robots have rigid structures and actuators requiring complex software control algorithms and sophisticated sensor systems in order to behave in a compliant and safe way adapted to contact with unknown environments and humans. By studying and constructing variable impedance actuators and their control, we contribute to the development of actuation units which can match the intrinsic safety, motion performance and energy efficiency of biological systems and in particular the human. As such, this may lead to a new generation of robots that can co-exist and co-operate with people and get closer to the human manipulation and locomotion performance than is possible with current robots.

ICRA Conference 2011 Conference Paper

Catching flying balls and preparing coffee: Humanoid Rollin'Justin performs dynamic and sensitive tasks

Berthold Bäuml
Florian Schmidt 0001
Thomas Wimböck
Oliver Birbach
Alexander Dietrich
Matthias Fuchs
Werner Friedl
Udo Frese

The mobile humanoid Rollin'Justin is a versatile experimental platform for research in manipulation tasks. Previously, different state of the art control methods and first autonomous task execution scenarios have been demonstrated. In this video two new applications with challenging task requirements are presented. One is the catching of one or even two flying balls using all of Justin's degrees of freedom. The other is the autonomous preparation of coffee. Both applications need adequate sensors to support local referencing. The required precision in position and timing is realized in software, using the sensor information, taking the varying precision of Justin's kinematic sub-chains into account and handling all timings in sub-millisecond range.

ICRA Conference 2011 Conference Paper

Dexhand: A Space qualified multi-fingered robotic hand

Maxime Chalon
Armin Wedler
Andreas Baumann
Wieland Bertleff
Alexander Beyer
Jörg Butterfaß
Markus Grebenstein
Robin Gruber

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.

IROS Conference 2011 Conference Paper

FAS A flexible Antagonistic spring element for a high performance over actuated hand

Werner Friedl
Maxime Chalon
Jens Reinecke
Markus Grebenstein

In robotic hands design tendon driven systems have been considered for years. The main advantage is a small end effector inertia e. g. a light, small hand with high dynamics due to remote actuators. To protect the actuators from impact in unknown environments a compliant mechanism can be used. It absorbs energy during an impact or saves energy to enhance the joint dynamics. In this paper an antagonistic tendon mechanism is presented. It fits 38 times in the DLR Hand Arm System forearm and enables is adapted to the different finger joints and different tendon lengths. A magnetic sensor was developed for the force measurement of the tendons. Finally, the calibration and the robustness are demonstrated through a set of experiments.

ICRA Conference 2011 Conference Paper

The DLR hand arm system

Markus Grebenstein
Alin Albu-Schäffer
Thomas Bahls
Maxime Chalon
Oliver Eiberger
Werner Friedl
Robin Gruber
Sami Haddadin

An anthropomorphic hand arm system using variable stiffness actuation has been developed at DLR. It is aimed to reach its human archetype regarding size, weight and performance. The main focus of our development is put on robustness, dynamic performance and dexterity. Therefore, a paradigm change from impedance controlled, but mechanically stiff joints to robots using intrinsic variable compliance joints is carried out.

ICRA Conference 2010 Conference Paper

Bidirectional antagonistic variable stiffness actuation: Analysis, design & Implementation

Florian Petit
Maxime Chalon
Werner Friedl
Markus Grebenstein
Alin Albu-Schäffer
Gerhard Hirzinger

The variable stiffness actuation concept is considered to provide a human-friendly robot technology. This paper examines a joint concept called the bidirectional antagonistic joint which is a extension of antagonistic joints. A new operating mode called the helping mode is introduced, which increases the joint load range. Although the joint can not be pretensioned in the helping mode, it is shown that a stiffness variation is possible, assuming a suitable torque-stiffness characteristic of the elastic elements. A methodology to design such characteristics is presented along with several example cases interpreted in a torque-stiffness plot. Furthermore, a stiffness adaptation control scheme which ensures mechanism safety is described. Finally, the design methodology and the control are evaluated on an implementation of a bidirectional antagonistic joint.

IROS Conference 2010 Conference Paper

The thumb: guidelines for a robotic design

Maxime Chalon
Markus Grebenstein
Thomas Wimböck
Gerhard Hirzinger

The impressive manipulation capabilities of the human hand are undoubtedly related to the thumb opposition. Such a versatility is highly desirable in the context of humanoid robots, in particular when performing object manipulation. Biomechanical data, surgery procedures and rehabilitation surveys represent an excellent base from which a robotic design can be inferred. This knowledge must be understood to identify the properties required for manipulation skills, and especially, to obtain a holistic view of the thumb functionality. Several designs have been realized, that concentrated on biomimetism or on classical mechanism designs. Therefore, it is currently difficult for designers to obtain a clear overview of the properties required for a functional robot thumb. In the present case, a robotic hand with size, forces, velocity and shape comparable to the human ones, is envisioned. Unlike most of robotic designs-where the fingers are modular and the thumb is simply a finger placed in opposition-the thumb benefits from an intensive functional analysis. This paper gathers anatomy, surgery and rehabilitation data and identifies the properties required for human like manipulation. Based on this synergy, guidelines are presented that are fused and applied to the hand design of the Integrated Hand arm project of DLR.

ICRA Conference 2009 Conference Paper

The DLR MiroSurge - A robotic system for surgery

Rainer Konietschke
Ulrich Hagn
Mathias Nickl
Stefan Jörg
Andreas Tobergte
Georg Passig
Ulrich Seibold
Luc Le Tien

This video presents the in-house developed DLR MiroSurge robotic system for surgery. As shown, the system is suitable for both minimally invasive and open surgery. Essential part of the system is the MIRO robot: The soft robotics feature enables intuitive interaction with the robot.

IROS Conference 2008 Conference Paper

The DLR-Crawler: A testbed for actively compliant hexapod walking based on the fingers of DLR-Hand II

Martin Görner
Thomas Wimböck
Andreas Baumann
Matthias Fuchs
Thomas Bahls
Markus Grebenstein
Christoph Borst 0001
Jörg Butterfaß

Walking is a fascinating way of locomotion that is very robust, especially in unstructured terrain. Many researchers devote their time to understanding its underlying principles and to build robots based on their findings. Using the fingers of DLR-Hand II a six-legged actively compliant walking robot is developed. It is intended to be used as testbed for the evaluation of different force- and position-based leg and gait control algorithms for hexapod walking in rough terrain. Following a brief overview of the finger hardware, the use of fingers as legs is analyzed and discussed. The body geometry as well as the systems constituting the robot are described. The compliance control algorithm used is explained and finally some experimental results are presented.

ICRA Conference 2007 Conference Paper

Feedback linearization and simultaneous stiffness-position control of robots with antagonistic actuated joints

Gianluca Palli
Claudio Melchiorri
Thomas Wimböck
Markus Grebenstein
Gerhard Hirzinger

In this paper, the dynamic model of a robot with antagonistic actuated joints is presented, and the problem of full linearization via static state feedback is analyzed. The use of transmission elements with nonlinear relation between the displacement and the actuated force allows to control both the position and the stiffness of each joint. The main advantage of this actuation modality is that the achieved stiffness becomes a mechanical characteristic of the system and it is not the result of an immediate control action as in the classical impedance control scheme (Davison, 2003). Different examples of implementation of this kind of devices are known in literature, even if limited to one single joint (Kjita et al. , 2003; Laumond and Kineocam, 2006; Mansard and Chaumette, 2004 and 2006) and the application of antagonistic actuated kinematic chains in the field of robotic hand design is under investigation (Stasse et al. , 2006). After a brief review of the dependence of the properties of antagonistic actuation on the transmission elements characteristics, a scheme for simultaneous stiffness-position control of the linearized system is presented. Finally, simulation results of a two-link antagonistic actuated arm are reported and discussed.

ICRA Conference 2006 Conference Paper

A Hands-on-robot for Accurate Placement of Pedicle Screws

Tobias Ortmaier
Holger Weiss
Ulrich Hagn
Markus Grebenstein
Matthias Nickel
Alin Albu-Schäffer
Christian Ott 0001
Stefan Jörg

This paper presents a novel system for accurate placement of pedicle screws. The system consists of a new light-weight (<10 kg), kinematically redundant, and fully torque controlled robot. Additionally, the pose of the robot tool-center point is tracked by an optical navigation system, serving as an external reference source. Therefore, it is possible to measure and to compensate deviations between the intraoperative and the preoperatively planned pose. The robotic arm itself is impedance controlled. This allows for a new intuitive man-machine-interface as the joint units are equipped with torque sensors: the robot can be moved just by pulling/pushing its structure. The surgeon has full control of the robot at every step of the intervention. The hand-eye-coordination problems known from manual pedicle screw placement can be omitted

ICRA Conference 2003 Conference Paper

DLR hand II: hard- and software architecture for information processing

Steffen Haidacher
Jörg Butterfaß
Max Fischer
Markus Grebenstein
Klaus Jöhl
Klaus Kunze
Matthias Nickel
Nikolaus Seitz

In the robotic community more and more hands have been developed. These newly designed manipulators greatly outperform their ancestors in terms of available sensor signals, applicable grasping force, mechanical stability, reliability, kinematic design and more. This development extends the possible range and complexity of applications of robotic grippers also to areas outside of well structured laboratories and simple tasks. It also calls for more flexible control structures to provide a framework for implementing and executing these newly arising tasks without having to start from scratch for each new task. During the last few years we developed a control system architecture for DLR hand II that proved to be useful for a great variety of different applications. This paper presents the basic ideas behind DLR hand II's hard- and software architecture adapted to new needs in data processing.

ICRA Conference 2003 Conference Paper

The HIT/DLR dexterous hand: work in progress

X. H. Gao
Minghe Jin
Li Jiang 0001
Zongwu Xie
P. He
L. Yang
Yiwei Liu 0001
Ran Wei

This paper presents the current work progress of HIT/DLR Dexterous Hand. Based on the technology of DLR Hand II, HIT and DLR are jointly developing a smaller and easier manufactured robot hand. The prototype of one finger has been successfully built. The finger has three DOF and four joints, the last two joints are mechanically coupled by a rigid linkage. All the actuators are commercial brushless DC motors with integrated analog Hall sensors. DSP based control system is implemented in PCI bus architecture and the serial communication between the hand and DSP needs only 6 lines(4 lines power supply and 2 lines communication interface). The fingertip force can reach 10N.

ICRA Conference 2001 Conference Paper

DLR-Hand II Next Generation of a Dextrous Robot Hand

Jörg Butterfaß
Markus Grebenstein
Hong Liu 0002
Gerhard Hirzinger

This paper outlines the 2nd generation of multisensory hand design at DLR, based on the results of the DLR Hand I we analysed. An open skeleton structure for better maintenance with semi-shell housing and the new automatically reconfigurable palm have been equipped with more powerful actuators to reach 30 N on the fingertip. The newly designed sensors as the 6-DOF fingertip force torque sensor, the integrated electronics and the new communication architecture with a reduction of cabling to the hand to only 12 lines, are outlined. The Cartesian impedance control of all the fingers completes the new 13-DOF hand.

ICRA Conference 2000 Conference Paper

A Mechatronics Approach to the Design of Light-Weight Arms and Multifingered Hands

Gerhard Hirzinger
Jörg Butterfaß
Max Fischer
Markus Grebenstein
Matthias Hähnle
Hong Liu 0002
Ingo Schäfer
Norbert Sporer

Describes design and development efforts in DLR's robotics lab towards a new generation of ultra-light weight robots with articulated hands. The design of fully sensorized joints with complete state feedback and the underlying mechanisms are outlined. The second light-weight arm generation is available now, as well as the second generation of a worldwide most highly integrated 4 finger-hand is available now. Thus we hope that important steps towards a new generation of service and personal robots have been achieved.