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Carsten Preusche

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22 papers

1 author row

ICRA Conference 2012 Conference Paper

A functional anatomy based kinematic human hand model with simple size adaptation

Frank P. J. van der Hulst
Simon Schätzle
Carsten Preusche
Andre Schiele

For the purpose of ergonomic human-machine interaction and geometrical design of hand held haptic devices, a kinematic model that represents the functional anatomy of different human hands is desired. It is the goal of this paper to present a kinematic hand model that is based on human physiology and that is easily adaptable to represent various real human hand sizes. This is achieved by exploiting body proportions to derive finger segment lengths from the hand length. A partial hand model validation, involving index- and middle finger validation using a group of subjects, indicates that the use of body proportions offers a good estimate of finger length from a given hand length. Model estimated fingertip positions over a motion trajectory remain within reasonable limits when compared with experimental data for this subject group. The model is promising for usage in practical situations since only hand length, which is easy to measure or to obtain from literature, is required as an input. Phalange lengths, which are sparsely available from literature and difficult to measure, are generated by the model.

ICRA Conference 2012 Conference Paper

Identification of contact formations: Resolving ambiguous force torque information

Katharina Hertkorn
Máximo A. Roa
Carsten Preusche
Christoph Borst 0001
Gerhard Hirzinger

This paper presents the identification of contact formations using force torque information. As force torque measurements do not map uniquely to their corresponding contact formations, three steps are performed: Initially, the wrench space for each contact formation is computed automatically. Then, a contact formation graph is augmented with a similarity index that reflects the similarity of contact formations with respect to their spanned wrench spaces. A particle filter is used to represent the likeliness of a contact formation given a force torque measurement. Finally, this probability distribution is resolved taking the similarity index, the transitions of the contact formation graph and the history of identified contact formations into account. This allows the recognition of the order of demonstrated contact formations by a measured set of forces and torques. The approach is verified by experiments.

IROS Conference 2011 Conference Paper

Network representation and passivity of delayed teleoperation systems

Jordi Artigas
Jee-Hwan Ryu
Carsten Preusche
Gerhard Hirzinger

In this paper, a decentralized platform for Simultaneous Localization and Mapping (SLAM) with multiple robots is developed. A novel occupancy grid map fusion algorithm is proposed. Map fusion is achieved through a multi-step process that includes image pre-processing, map learning, relative transformation extraction and then verification of the results. The proposed map learning method is a process based on the Self Organizing Map (SOM). In the learning phase, the obstacles of the map are learned by clustering the occupied cells of the map. The clusters represent the spatial form of the map and make further analyses of the map easier and faster. Also, clusters can be interpreted as features extracted from the occupancy grid map so the map fusion problem becomes a task of matching features. Results of the experiments from tests performed on a real environment with multiple robots prove the effectiveness of the proposed solution.

IROS Conference 2011 Conference Paper

Subspace-oriented energy distribution for the Time Domain Passivity Approach

Christian Ott 0001
Jordi Artigas
Carsten Preusche

The Time Domain Passivity Control Approach (TDPA) is a powerful tool to guarantee passive interaction between a robot and its environment. Rather than establishing fixed control parameters to keep the system stable in any possible environment, the TDPA observes the energy flow due to the interaction and applies a dissipative term in the case the interaction becomes active. In a robot manipulator the rationale behind the Passivity Controller requires a criterion on how to distribute the energy to be dissipated among the multiple joints and must be adjusted according to the general control goal of the application. This paper presents a method for distributing the dissipation between decoupled subspaces of a redundant manipulator, prioritizing dissipation in the null-space. The method allows to preserve passivity while avoiding disturbance of the general control goal defined in the task-space. Thus the general control goal can, to some extent, be as well decoupled from passivity considerations and thus a less conservative controller can be achieved. The approach is sustained with a numerical simulation.

ICRA Conference 2011 Conference Paper

The DLR bimanual haptic device with optimized workspace

Thomas Hulin
Katharina Hertkorn
Philipp Kremer
Simon Schätzle
Jordi Artigas
Mikel Sagardia
Franziska Zacharias
Carsten Preusche

This article accompanies a video that presents a bimanual haptic device composed of two DLR/KUKA Light-Weight Robot (LWR) arms. The LWRs have similar dimensions to human arms, and can be operated in torque and position control mode at an update rate of 1 kHz. The two robots are mounted behind the user, such that the intersecting workspace of the robots and the human arms becomes maximal. In order to enhance user interaction, various hand interfaces and additional tactile feedback devices can be used together with the robots. The presented system is equipped with a thorough safety architecture that assures safe operation for human and robot. Additionally, sophisticated control strategies improve performance and guarantee stability. The introduced haptic system is well suited for versatile applications in remote and virtual environments, especially for large unscaled movements.

ICRA Conference 2010 Conference Paper

High-fidelity telepresence and teleaction

Robert Bauernschmitt
Martin Buss
Barbara Deml
Klaus Diepold
Berthold Färber
Georg Färber
Ulrich Hagn
Gerhard Hirzinger

The collaborative research center SFB453 (www. sfb453.de) aims to realize high-fidelity telepresence and teleaction systems.

IROS Conference 2010 Conference Paper

Position drift compensation in time domain passivity based teleoperation

Jordi Artigas
Jee-Hwan Ryu
Carsten Preusche

The Time Domain Passivity Control Approach is gathering interest in the robotics field. Simplicity and flexibility and the fact that system design emerges from ideal cases make it a powerful stability tool for teleoperation systems. Communication time delay is an inherent attribute of nearly every realistic teleoperation system. Unless the communication channel guarantees transmission delays of less than the system sampling time, the delay must be considered in the design in order to guarantee stability and satisfy a desired degree of performance. In previous work it has been shown how passivity can be considered in the time domain and how control rules are derived from it in order to dissipate the energy produced by the delayed communication. However, a weakness of these approaches is the impossibility of observing the exact amount of energy stored in the communication channel due to its delayed nature. A passive estimation is therefore needed which outcomes in an over-dissipation and in turn impacts on transparency. In constrained communications over-dissipation may become apparent in the form of a non-neglectful position drift between master and slave. This paper tackles the over-dissipative behavior of the Passivity Controller by resembling the energetic behavior of an ideal communication, i. e. where no delay is present and the transmission is lossless. Thus, the communication channel is not just controlled to be passive, as has been the case up to now, but also lossless. Energy can be dissipated to prevent activity, but activity can be also produced to prevent dissipative behaviors. The approach is sustained with experimental results.

ICRA Conference 2010 Conference Paper

Time Domain Passivity Control for multi-degree of freedom haptic devices with time delay

Katharina Hertkorn
Thomas Hulin
Philipp Kremer
Carsten Preusche
Gerhard Hirzinger

This paper generalizes the Time Domain Passivity Control concept originally introduced by J. -H. Ryu et al. (2004) in order to work for multi-degree of freedom (DoF) haptic systems with time delay. Its energy computation (named passivity observer) factors in the phase shift caused by time delay, and is improved by an energy estimation. Moreover, the variable damping of the passivity controller is generalized such that weighting by the mass matrix of the haptic device is possible. This transformation takes into account the direction-dependent inertia of multi-DoF haptic devices. Furthermore, a stability boundary for this damping is introduced for one as well as for several DoF allowing for high energy dissipation. Additionally, it is briefly shown that one single multi-DoF Cartesian passivity controller is advantageous compared to independent single-DoF passivity controllers in each joint of the haptic device. Finally, the generalized Time Domain Passivity Controller is experimentally verified using the DLR light weight robot arm as haptic device.

ICRA Conference 2009 Conference Paper

Multimodal telepresent control of DLR's Rollin' JUSTIN

Philipp Kremer
Thomas Wimböck
Jordi Artigas
Simon Schätzle
Klaus Jöhl
Florian Schmidt 0001
Carsten Preusche
Gerhard Hirzinger

This video presents a telepresence system which enables a human operator to explore a remote environment by means of a multimodal man machine interface and rollin' JUSTIN as teleoperator. The man machine interface allows for bimanual, dexterous manipulation and, through two different operating modi of the man machine interface, wide area movement as well. A bimanual assembly task, consisting of grasping a connector, opening and closing it again, is shown in this video.

ICRA Conference 2009 Conference Paper

Passive event-based extrapolation for lossy haptic data compression in bilateral presence systems

Philipp Kremer
Martin Kuschel
Carsten Preusche
Martin Buss
Gerhard Hirzinger

A new lossy compression method is proposed for haptic (force, velocity) data as exchanged in bilateral telepresence systems. The method is based on the passive extrapolative compression strategy proposed in the work of Kuschel et al. (2006). The innovation is that the extrapolations do not have a stiff horizon, but are triggered by considerable changes (events) in the target environment. This enables longer average extrapolation horizons and thus, higher compression. Experiments are conducted using two DLR light weight robots. The results indicate that the method outperforms older implementations.

ICRA Conference 2008 Conference Paper

Bilateral energy transfer in delayed teleoperation on the time domain

Jordi Artigas
Carsten Preusche
Gerhard Hirzinger
Gianni Borghesan
Claudio Melchiorri

The time domain passivity framework is attracting interest as a method for granting stability in both telerobotics and haptic contexts; this paper employs this approach in order to introduce a novel concept, the Bilateral Energy Transfer for haptic telepresence. Loosely speaking, the Bilateral Energy Transfer is the straightforward transfer of energy between the two opposite sides of a teleoperation network, the master and slave robots. In an ideal telepresence scenario master and slave robots behave as rigid connected masses [1], and their power exchange is lossless; conversely, realistic scenarios include sources of energy leaks, i. e. elements that modify the power flows in the network. Moreover, if energy leaks have an active nature, they become source of instability for the system. This work isolates two sources of instability normally present in a teleoperation system, i. e. the delayed communication channel and robot velocity estimation based on digital position acquisition. These energy leaks are counterbalanced by two independent controllers, whose design is based on energetic consideration, and whose employment allows to achieve the Bilateral Energy Transfer. The presented arguments are sustained by simulations and experiments.

IROS Conference 2008 Conference Paper

Stability boundary for haptic rendering: Influence of human operator

Thomas Hulin
Carsten Preusche
Gerhard Hirzinger

Recent analysis on the stability boundary for haptic rendering assumed a stabilizing effect through a human operator holding a haptic device, without considering his/her dynamics directly. This paper derives stability boundaries of a linear model of a haptic system including those dynamics. It shows that all three elements of the human arm modeled as mass-spring-damper system contribute to stability. The haptic system itself is composed of a haptic device colliding with a virtual wall modeled as time-delayed discrete-time spring-damper system. Furthermore, the article proves that the recently found linear stability condition for haptic devices of Gil et al. still holds if a human is holding the haptic device. Finally, a relation to Colgatepsilas passivity condition defining a robustly stable region is given.

ICRA Conference 2007 Conference Paper

Stability Boundary for Haptic Rendering: Influence of Damping and Delay

Jorge Juan Gil
Emilio Sánchez
Thomas Hulin
Carsten Preusche
Gerhard Hirzinger

The influence of viscous damping and delay on the stability of haptic systems is studied in this paper. The stability boundaries have been found by means of different approaches. Although the shape of these stability boundaries is quite complex, a new linear condition which summarizes the relation between virtual stiffness, viscous damping and delay is proposed. This condition is independent of the mass of the haptic device. The theoretical results are supported by simulations and experimental data using the DLR light-weight robot.

ICRA Conference 2007 Conference Paper

Stable Bilateral Control of Teleoperators Under Time-varying Communication Delay: Time Domain Passivity Approach

Jee-Hwan Ryu
Carsten Preusche

In this paper, modified two-port time-domain passivity approach is proposed for stable bilateral control of teleoperators under time-varying communication delay. We separate input and output energy at each port of a bilateral controller, and propose a sufficient condition for satisfying the passivity of the bilateral controller including time-delay. Output energy at the master port should be less than the transmitted input energy from the slave port with time-delay, and output energy at the slave port should be less than the transmitted input energy from the master port with time-delay. For satisfying above two conditions, two passivity controllers are attached at each port of the bilateral controller. Teleoperation experiment with about 120 (msec) of time-delay each way is performed. Stable teleoperation is achieved in free motion and hard contact as well.

IROS Conference 2007 Conference Paper

Time domain passivity for delayed haptic telepresence with energy reference

Jordi Artigas
Carsten Preusche
Gerhard Hirzinger

This paper presents a new control strategy based on the time domain passivity control approach which copes with the active nature of delayed communication channels. Describing the system by means of network elements, the energy of the communication channel can be computed in real time and subsequently dissipated, thus providing stable operation. This is done bilaterally, since the system energy may flow from master to slave and from slave to master. The approach is accompanied with some experiments which validate the method.

IROS Conference 2006 Conference Paper

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

Klaus Landzettel
Carsten Preusche
Alin Albu-Schäffer
Detlef Reintsema
Bernhard Rebele
Gerhard Hirzinger

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

IROS Conference 2006 Conference Paper

Robotics Component Verification on ISS ROKVISS Preliminary Results for Telepresence

Carsten Preusche
Detlef Reintsema
Klaus Landzettel
Gerhard Hirzinger

ROKVISS, Germany's 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

IROS Conference 2006 Conference Paper

Stability Boundary for Haptic Rendering: Influence of Physical Damping

Thomas Hulin
Carsten Preusche
Gerhard Hirzinger

Physical damping is increasing the z-width of haptic simulations. This paper derives the normalized stability boundaries for physically damped one degree of freedom haptic devices colliding with a virtual wall represented as spring-damper system. These boundaries are independent of the haptic device's mass and the sampling time. Furthermore, the dependency of the maximum stable virtual stiffness is discussed. Moreover, this paper illustrates that the passive region which is defined by Colgate's passivity condition is a subset inside the stable region for undelayed systems, but not for delayed systems

IROS Conference 2006 Conference Paper

Time Domain Passivity Control-based Telepresence with Time Delay

Jordi Artigas
Jordi Vilanova
Carsten Preusche
Gerhard Hirzinger

This paper analyses the time domain passivity control approach in the time-delayed telepresence context, and proposes a method which provides stable operation. The passivity controller for the two-port network which is created by the bilateral control and communication elements in (J. H. Ryu, et al. , May 2002) is shown to be not valid if a time delay is introduced in the communication channel. Classical stability analysis for the delayed system is presented and used as argument and benchmark for the proposed solution. Simulations and experimental results are discussed and compared with classical stability analysis

IROS Conference 2003 Conference Paper

Time domain passivity control for 6 degrees of freedom haptic displays

Carsten Preusche
Gerhard Hirzinger
Jee-Hwan Ryu
Blake Hannaford

In this paper a modification of the time domain passivity controller is presented to improve its performance and transparency in case of multi degrees of freedom (dof) haptic interaction. In multi-dof application the concept needs to be extended by additional conditions to distribute the adaptive damping appropriately among the degrees of freedom. This can be solved by using the geometrical information coded in the output signals of the system. Experiments show the validity of this concept.

IROS Conference 2003 Conference Paper

Time domain passivity control with reference energy behavior

Jee-Hwan Ryu
Blake Hannaford
Carsten Preusche
Gerhard Hirzinger

A recently proposed method for stabilizing haptic interfaces and teleoperation systems was tested with a "PHANToM" commercial haptic device. The "passivity observer" (PO) and "passivity controller" (PC) stabilization method was formed to stabilize the system but also excite high frequency mode in the device. To solve this problem, we propose a method to use a time-varying desired energy threshold instead of fixed zero energy threshold for the PO, and make the actual energy input follow the time-varying energy threshold. With the time-varying energy threshold, we make the PC control action smooth without sudden impulsive behavior by distributing the dissipation. The proposed new PO/PC approach is applied to PHANToM with high stiffness (K=500 N/m), and stable and smooth contact is guarantee. Resetting and active environment display problems can also be solved with the reference energy following idea.

ICRA Conference 2002 Conference Paper

Flexible Multimodal Telepresent Assembly using a Generic Interconnection Framework

Carsten Preusche
Jens Hoogen
Detlef Reintsema
Günther Schmidt 0001
Gerhard Hirzinger

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.