About me
I am a researcher in the Language Technology Lab
at the German Research Center for Artifical
Intelligence (DFKI GmbH) and a PhD candidate at Saarland University.
Currently, my research is sponsored by the EU-funded project CogX.
Before that I was part of the CoSy project. My research
interests lie in linguistic aspects of spatial cognition for autonomous robots and other
embodied agents, and in situated human-robot
interaction in general. I studied Computational Linguistics at
Saarland University in Saarbrücken, Germany, where I obtained a degree
as Diplom-Linguist (Computerlinguistik).
May 2010
I have a new phone number!
February 2010
I am co-organizing the
Workshop on Interactive Communication for Autonomous Intelligent Robots (ICAIR).
It will be held in conjunction with the 2010 IEEE International Conference on Robotics and Automation
(ICRA 2010), Anchorage, Alaska, May 3-8, 2010.
Check out the
Call for Participation.
For more publications related to the talking robots group, please have a look at
our group's publication list.
2010
Marc Hanheide, Nick Hawes, Jeremy L. Wyatt, Moritz Göbelbecker, Michael Brenner, Kristoffer
Sjöö, Alper Aydemir, Patric Jensfelt, Hendrik Zender, and Geert-Jan M. Kruijff (2010).
A Framework for Goal Generation and Management.
In Proceedings of the AAAI Workshop on Goal-Directed Autonomy.
Atlanta, GA, USA, July 2010.
[Abstract]
[BibTeX]
[PDF]
Goal-directed behaviour is often viewed as an essential characteristic of an intelligent system, but
mechanisms to generate and manage goals are often overlooked. This paper addresses this by
presenting a framework for autonomous goal generation and selection. The framework has been
implemented as part of an intelligent mobile robot capable of exploring unknown space and
determining the category of rooms autonomously. We demonstrate the efficacy of our approach by
comparing the performance of two versions of our integrated system: one with the framework, the
other without. This investigation leads us conclude that such a framework is desirable for an
integrated intelligent system because it reduces the complexity of the problems that must be solved
by other behaviour-generation mechanisms, it makes goal-directed behaviour more robust in the face
of a dynamic and unpredictable environment, and it provides an entry point for domain-specific
knowledge in a more general system.
@inproceedings{hanheide/etal:2010-fgg,
author = {Hanheide, Marc and Hawes, Nick and Wyatt, Jeremy L. and G{\"o}belbecker, Moritz
and Brenner, Michael and Sj\"{o}\"{o}, Kristoffer and Aydemir, Alper and
Jensfelt, Patric and Zender, Hendrik and Kruijff, Geert-Jan M.},
title = {A Framework for Goal Generation and Management},
booktitle = {Proceedings of the {AAAI} Workshop on Goal-Directed Autonomy},
address = {Atlanta, GA, USA},
organization = {AAAI},
month = {July},
year = {2010}}
Hendrik Zender, Christopher Koppermann, Fai Greeve, and Geert-Jan M. Kruijff (2010).
Anchor-Progression in Spatially Situated Discourse: a Production Experiment.
In Proceedings of the Sixth International Natural Language Generation Conference (INLG 2010).
Trim, Co. Meath, Ireland, July 2010.
[Abstract]
[BibTeX]
[PDF]
The paper presents two models for producing and understanding situationally appropriate referring
expressions (REs) during a discourse about large-scale space. The models are evaluated against an
empirical production experiment.
@inproceedings{zender/etal:2010-inlg,
author = {Zender, Hendrik and Koppermann, Christopher and Greeve, Fai
and Kruijff, Geert-Jan M.},
title = {Anchor-Progression in Spatially Situated Discourse: a Production Experiment},
booktitle = {Proceedings of the Sixth International Natural Language Generation Conference
({INLG 2010})},
pages = {209--213},
address = {Trim, Co. Meath, Ireland},
organization = {Association for Computational Linguistics},
month = {July},
year = {2010}}
Marc Hanheide and Hendrik Zender (2010).
Proceedings of the ICRA 2010 Workshop on Interactive Communication for Autonomous Intelligent
Robots (ICAIR).
Anchorage, AK, USA. May 2010.
[BibTeX]
[PDF]
[Workshop Homepage]
@proceedings{hanheide/zender:2010-icairproc,
editor = {Hanheide, Marc and Zender, Hendrik},
title = {Proceedings of the {ICRA} 2010 Workshop on Interactive Communication for
Autonomous Intelligent Robots ({ICAIR})},
address = {Anchorage, AK, USA},
month = {May},
year = {2010}}
Andrzej Pronobis, Patric Jensfelt, Kristoffer Sjöö, Hendrik Zender,
Geert-Jan M. Kruijff, Óscar Martínez Mozos, and Wolfram Burgard (2010).
Semantic Modelling of Space.
In Henrik Iskov Christensen, Geert-Jan M. Kruijff, and Jeremy L. Wyatt, editors,
Cognitive Systems, volume 8 of Cognitive Systems Monographs,
chapter 5.
Springer Verlag, Berlin/Heidelberg, Germany, April 2010.
[BibTeX]
[Springer]
[CoSy Book Website]
@incollection{cosybook:space,
author = {Pronobis, Andrzej and Jensfelt, Patric and Sj\"{o}\"{o}, Kristoffer and
Zender, Hendrik and Kruijff, Geert-Jan M. and Mozos, \'{O}scar Mart\'{i}nez
and Burgard, Wolfram},
title = {Semantic Modelling of Space},
editor = {Christensen, Henrik Iskov and Kruijff, Geert-Jan M. and Wyatt, Jeremy L.},
booktitle = {Cognitive Systems},
chapter = {5},
pages = {165--221},
series = {Cognitive Systems Monographs},
publisher = {Springer Verlag},
address = {Berlin/Heidelberg, Germany},
volume = {8},
year = {2010}}
Geert-Jan M. Kruijff, Pierre Lison, Trevor Benjamin, Henrik Jacobsson, Hendrik
Zender,and Ivana Kruijff-Korbayová (2010).
Situated Dialogue Processing for Human-Robot Interaction.
In Henrik Iskov Christensen, Geert-Jan M. Kruijff, and Jeremy L. Wyatt, editors,
Cognitive Systems, volume 8 of Cognitive Systems Monographs,
chapter 8.
Springer Verlag, Berlin/Heidelberg, Germany, April 2010.
[BibTeX]
[Springer]
[CoSy Book Website]
@incollection{cosybook:dialogue,
author = {Kruijff, Geert-Jan M. and Lison, Pierre and Benjamin, Trevor and Jacobsson,
Henrik and Zender, Hendrik and Kruijff-Korbayov\'{a}, Ivana},
title = {Situated Dialogue Processing for Human-Robot Interaction},
editor = {Christensen, Henrik Iskov and Kruijff, Geert-Jan M. and Wyatt, Jeremy L.},
booktitle = {Cognitive Systems},
chapter = {8},
pages = {311--364},
series = {Cognitive Systems Monographs},
publisher = {Springer Verlag},
address = {Berlin/Heidelberg, Germany},
volume = {8},
year = {2010}}
Kristoffer Sjöö, Hendrik Zender, Patric Jensfelt, Geert-Jan M. Kruijff,
Andrzej Pronobis, Nick Hawes, and Michael Brenner (2010).
The Explorer System.
In Henrik Iskov Christensen, Geert-Jan M. Kruijff, and Jeremy L. Wyatt, editors,
Cognitive Systems, volume 8 of Cognitive Systems Monographs,
chapter 10.
Springer Verlag, Berlin/Heidelberg, Germany, April 2010.
[BibTeX]
[Springer]
[CoSy Book Website]
@incollection{cosybook:explorer,
author = {Sj\"{o}\"{o}, Kristoffer and Zender, Hendrik and Jensfelt, Patric and Kruijff,
Geert-Jan M. and Pronobis, Andrzej and Hawes, Nick and Brenner, Michael},
title = {The {Explorer} System},
editor = {Christensen, Henrik Iskov and Kruijff, Geert-Jan M. and Wyatt, Jeremy L.},
booktitle = {Cognitive Systems},
chapter = {10},
pages = {395--421},
series = {Cognitive Systems Monographs},
publisher = {Springer Verlag},
address = {Berlin/Heidelberg, Germany},
volume = {8},
year = {2010}}
Alper Aydemir, Michael Brenner, Moritz Göbelbecker, Marc Hanheide, Nick Hawes, Patric
Jensfelt, Geert-Jan M. Kruijff, Ivana Kruijff-Korbayová, Pierre Lison, Kristoffer
Sjöö, Jeremy Wyatt, Hendrik Zender, and Michael Zillich (2010).
Dora The Explorer: A Mobile Robot Motivated by Curiosity
Proceedings of the 4th International Conference on Cognitive Systems (CogSys 2010).
Zürich, Switzerland. January 2010.
[Poster PDF]
2009
Hendrik Zender, Geert-Jan M. Kruijff, and Ivana Kruijff-Korbayová (2009b).
Situated Resolution and Generation of Spatial Referring Expressions for Robotic Assistants.
Twenty-first International Joint Conference on Artificial Intelligence (IJCAI-09).
AAAI. Pasadena, CA, USA. July 2009.
[Abstract]
[BibTeX]
[PDF]
In this paper we present an approach to the task of generating and
resolving referring expressions (REs) for conversational mobile robots.
It is based on a spatial knowledge base encompassing both robot- and
human-centric representations. Existing algorithms for the generation
of referring expressions (GRE) try to find a description that uniquely
identifies the referent with respect to other entities
that are in the current context. Mobile robots, however,
act in large-scale space, that is environments that are larger than
what can be perceived at a glance, e.g. an office building with
different floors, each containing several rooms and
objects. One challenge when referring to elsewhere is thus to
include enough information so that the interlocutors can extend
their context appropriately. We address this challenge with a method
for context construction that can be used for both generating and resolving
REs – two previously disjoint aspects. Our approach is embedded in a
bi-directional framework for natural language processing for robots.
@inproceedings{zender/etal:2009-ijcai,
author = {Hendrik Zender and Geert-Jan M. Kruijff and Ivana Kruijff-Korbayov\'{a}},
title = {Situated Resolution and Generation of Spatial Referring Expressions
for Robotic Assistants},
booktitle = {Proceedings of the Twenty-First International Joint Conference on
Artificial Intelligence (IJCAI-09)},
pages = {1604--1609},
address = {Pasadena, CA, USA},
month = {July},
year = {2009},
url = {http://www.dfki.de/~zender/publications/zender_etal09-ijcai.pdf}}
Nick Hawes, Hendrik Zender, Kristoffer Sjöö, Michael Brenner, Geert-Jan M. Kruijff, and Patric Jensfelt (2009).
Planning and Acting with an Integrated Sense of Space
IJCAI Workshop on Hybrid Control of Autonomous Systems (HYCAS).
Pasadena, CA, USA. July 2009.
[Abstract]
[BibTeX]
[PDF]
The paper describes PECAS, an architecture for intelligent systems,
and its application in the Explorer, an interactive mobile robot.
PECAS is a new architectural combination of information fusion and
continual planning. PECAS plans, integrates and monitors the asynchronous
flow of information between multiple concurrent systems. Information fusion
provides a suitable intermediary to robustly couple the various reactive
and deliberative forms of processing used concurrently in the Explorer.
The Explorer instantiates PECAS around a hybrid spatial model combining SLAM,
visual search, and conceptual inference. This paper describes the
elements of this model, and demonstrates on an implemented scenario how PECAS provides
means for flexible control.
@inproceedings{hawes/etal:2009-hycas,
author = {Nick Hawes and Hendrik Zender and Kristoffer Sj\"{o}\"{o} and Michael Brenner
and Geert-Jan M. Kruijff and Patric Jensfelt},
title = {Planning and Acting with an Integrated Sense of Space},
booktitle = {Proceedings of the 1st International Workshop on Hybrid Control of Autonomous
Systems -- Integrating Learning, Deliberation and Reactive Control (HYCAS)},
pages = {25--32},
address = {Pasadena, CA, USA},
month = {July},
year = {2009},
url = {http://www.dfki.de/~zender/publications/hawes_etal09-hycas.pdf}}
Hendrik Zender, Geert-Jan M. Kruijff, and Ivana Kruijff-Korbayová (2009a).
A Situated Context Model for Resolution and Generation of Referring Expressions
12th European Workshop on Natural Language Generation (ENLG 2009).
pp. 126--129. ACL. Athens, Greece. March 2009.
[Abstract]
[BibTeX]
[PDF]
[Poster PDF]
The background for this paper is the aim to build robotic assistants that
can naturally interact with humans. One prerequisite for this is that
the robot can correctly identify objects or places a user refers to, and
produce comprehensible references itself. As robots typically act in
environments that are larger than what is immediately perceivable, the
problem arises how to identify the appropriate context, against which to
resolve or produce a referring expression (RE). Existing algorithms for
generating REs generally by-pass this problem by assuming a given context.
In this paper, we explicitly address this problem, proposing a method for
context determination in large-scale space. We show how it can be applied
both for resolving and producing REs.
@inproceedings{zender/etal:2009-enlg,
author = {Hendrik Zender and Geert-Jan M. Kruijff and Ivana Kruijff-Korbayov\'{a}},
title = {A Situated Context Model for Resolution and Generation of Referring
Expressions},
booktitle = {Proceedings of the 12th European Workshop on Natural Language Generation
(ENLG 2009)},
address = {Athens, Greece},
month = {March},
year = {2009},
publisher = {Association for Computational Linguistics},
pages = {126--129},
url = {http://www.aclweb.org/anthology/W09-0622}}
2008
Hendrik Zender, Óscar Martínez Mozos, Patric Jensfelt,
Geert-Jan M. Kruijff, and Wolfram Burgard (2008).
Conceptual Spatial Representations for Indoor Mobile Robots
Robotics and Autonomous Systems, Special Issue "From Sensors to Human Spatial Concepts".
Vol. 56, Issue 6. pp. 493--502. Elsevier. June 2008.
[Abstract]
[BibTeX]
[Author's manuscript PDF]
[DOI]
We present an approach for creating conceptual representations of human-made
indoor environments using mobile robots. The concepts refer to spatial and
functional properties of typical indoor environments. Following findings in
cognitive psychology, our model is composed of layers representing maps at
different levels of abstraction. The complete system is integrated in a mobile
robot endowed with laser and vision sensors for place and ob ject recognition.
The system also incorporates a linguistic framework that actively supports the
map acquisition process, and which is used for situated dialogue. Finally,
we discuss the capabilities of the integrated system.
@article{zender/etal:2008-ras_fs2hsc,
author = {Hendrik Zender and \'{O}scar Mart\'{i}nez Mozos and
Patric Jensfelt and Geert-Jan M. Kruijff and Wolfram Burgard},
title = {Conceptual Spatial Representations for Indoor Mobile Robots},
journal = {Robotics and Autonomous Systems},
publisher = {Elsevier},
doi = {10.1016/j.robot.2008.03.007},
volume = {56},
number = {6},
pages = {493--502},
month = {June},
year = {2008}}
Geert-Jan M. Kruijff and Hendrik Zender and Marc Hanheide and Britta Wrede (2008).
Proceedings of the ICRA 2008 Workshop: Social Interaction with Intelligent Indoor Robots (SI3R)
Pasadena, CA, USA. May 2008.
[Abstract]
[BibTeX]
[PDF]
[Workshop Homepage]
Robots are moving from the factories into our homes. Today, we have the Roomba.
Tomorrow, in 2010, industry aims to give us the first commercial humanoids.
Bringing robots as assistants into homes, offices, and shopping malls presents
serious challenges to human-robot interaction. Robots will need to assist untrained
users. Robots will need to interact with people in environments that are designed
for, and populated by, humans. This workshop focuses on how robotic systems can be
designed such as to meet these challenges. Make robots adapt to
the environment. Make robots socially acceptable. Make robots fit into the environment,
without the environment needing to be made to fit them.
@proceedings{si3r-icra-proc:2008,
editor = {Geert-Jan M. Kruijff and Hendrik Zender and Marc Hanheide and Britta Wrede},
title = {Proceedings of the ICRA 2008 Workshop:
Social Interaction with Intelligent Indoor Robots (SI3R)},
address = {Pasadena, CA, USA},
month = {May},
year = {2008}}
2007
Hendrik Zender and Geert-Jan M. Kruijff (2007).
Towards Generating Referring Expressions in a Mobile Robot Scenario
Language and Robots: Proceedings from the Symposium (LangRo'2007).
pp. 101--106.
Aveiro, Portugal. December 2007.
[Abstract]
[BibTeX]
[PDF]
This paper describes an approach towards generating
referring expressions that identify and distinguish spatial entities in
large-scale space, e.g. in an office environment, for autonomous mobile
robots. In such a scenario a dialogue is often about things and places
outside the current perceptual fields of the interlocutors. One of the
challenges therefore lies in determining an appropriate dialogue
context. Other important issues are to have adequate models of both the
large-scale spatial environment and of the user's knowledge.
@inproceedings{zender/kruijff:2007-langro,
author = {Hendrik Zender and Geert-Jan M. Kruijff},
title = {Towards Generating Referring Expressions in a Mobile Robot Scenario},
booktitle = {Language and Robots: Proceedings of the Symposium},
pages = {101--106},
address = {Aveiro, Portugal},
month = {December},
year = {2007}}
Óscar Martínez Mozos, Patric Jensfelt, Hendrik Zender,
Geert-Jan M. Kruijff, and Wolfram Burgard (2007b).
An Integrated System for Conceptual Spatial Representations
of Indoor Environments for Mobile Robots
Proceedings of the IROS 2007 Workshop: From Sensors to Human Spatial Concepts (FS2HSC).
pp. 25--32.
San Diego, CA, USA. November 2007.
[Abstract]
[BibTeX]
[PDF]
We present an integrated approach for creating conceptual
representations of human-made environments using mobile robots. The concepts
represent spatial and functional properties of typical indoor environments. Our
model is composed of layers which represent maps at different levels of
abstraction. The complete system was integrated in a service robot which
is endowed with laser and vision sensors for place and object recognition.
It also incorporates a linguistic framework that actively supports the map
acquisition process and is used for situated dialogue.
In the experiments we show how the robot acquires the conceptual information
and how it is used for situational and functional awareness.
@inproceedings{mozos/etal:2007-irosws,
author = {\'{O}scar Mart\'{i}nez Mozos and Patric Jensfelt and Hendrik Zender
and Geert-Jan M. Kruijff and Wolfram Burgard},
title = {An Integrated System for Conceptual Spatial
Representations of Indoor Environments for Mobile Robots},
booktitle = {Proceedings of the IROS 2007 Workshop:
From Sensors to Human Spatial Concepts (FS2HSC)},
pages = {25--32},
address = {San Diego, CA, USA},
month = {November},
year = {2007}}
Hendrik Zender, Patric Jensfelt, and Geert-Jan M. Kruijff (2007).
Human- and Situation-Aware People Following
Proceedings of the 16th IEEE International Symposium on Robot and Human
Interactive Communication (RO-MAN 2007).
pp. 1131--1136.
Jeju Island, Korea. August 2007.
[Abstract]
[BibTeX]
[PDF]
The paper presents an approach to intelligent,
interactive people following for autonomous robots.
The approach combines robust methods for simultaneous
localization and mapping and for people tracking in
order to yield a socially and environmentally
sensitive people following behavior. Unlike current
purely reactive approaches ("nearest point
following") it enables the robot to follow
a human in a socially acceptable way, providing
verbal and non-verbal feedback to the user where
necessary. At the same time, the robot makes use of
information about the spatial and functional
organization of its environment, so that it can
anticipate likely actions performed by a human, and
adjust its motion accordingly. As a result, the
robot's behaviors become less reactive and more
intuitive when following people around an indoor
environment. The approach has been fully implemented
and tested.
@inproceedings{zender/etal:2007-roman,
author = {Hendrik Zender and Patric Jensfelt and Geert-Jan M. Kruijff},
title = {Human- and Situation-Aware People Following},
booktitle = {Proc. of the 16th IEEE International Symposium on Robot and Human
Interactive Communication (RO-MAN 2007)},
pages = {1131--1136},
address = {Jeju Island, Korea},
month = {August},
year = {2007}}
Hendrik Zender, Patric Jensfelt, Óscar Martínez Mozos,
Geert-Jan M. Kruijff, and Wolfram Burgard (2007).
An Integrated Robotic System for Spatial Understanding and Situated
Interaction in Indoor Environments
Proceedings of the Twenty-Second Conference on Artificial Intelligence
(AAAI-07), Special Track on Integrated Intelligence.
pp. 1584--1589.
Vancouver, BC, Canada. July 2007.
[Abstract]
[BibTeX]
[PDF]
[Poster PDF]
A major challenge in robotics and artificial intelligence
lies in creating robots that are to cooperate with people
in human-populated environments, e.g. for domestic assistance
or elderly care. Such robots need skills that allow
them to interact with the world and the humans living
and working therein. In this paper we investigate the
question of spatial understanding of human-made environments.
The functionalities of our system comprise
perception of the world, natural language, learning, and
reasoning. For this purpose we integrate state-of-the-art
components from different disciplines in AI, robotics
and cognitive systems into a mobile robot system. The
work focuses on the description of the principles we
used for the integration, including cross-modal integration,
ontology-based mediation, and multiple levels of
abstraction of perception. Finally, we present experiments
with the integrated "CoSy Explorer" system and
list some of the major lessons that were learned from its
design, implementation, and evaluation.
@inproceedings{zender/etal:2007-aaaiii,
author = {Hendrik Zender and Patric Jensfelt and \'{O}scar Mart\'{i}nez Mozos and
Geert-Jan M. Kruijff and Wolfram Burgard},
title = {An Integrated Robotic System for Spatial Understanding and
Situated Interaction in Indoor Environments},
booktitle = {Proc. of the Twenty-Second Conference on Artificial Intelligence (AAAI-07)},
pages = {1584--1589},
address = {Vancouver, British Columbia, Canada},
month = {July},
year = {2007}}
Óscar Martínez Mozos, Patric Jensfelt, Hendrik Zender,
Geert-Jan M. Kruijff, and Wolfram Burgard (2007a).
From Labels to Semantics: An Integrated System for Conceptual Spatial Representations
of Indoor Environments for Mobile Robots
Proceedings of the ICRA-07 Workshop on Semantic Information in Robotics (SIR).
pp. 33--40.
Rome, Italy. April 2007.
[Abstract]
[BibTeX]
[PDF]
We present an integrated approach for creating conceptual
representations of human-made environments using mobile robots. The concepts
represent spatial and functional properties of typical indoor environments. Our
model is composed of layers which represent maps at different levels of
abstraction. The complete system was integrated in a service robot which
is endowed with laser and vision sensors for place and object recognition.
It also incorporates a linguistic framework that actively supports the map
acquisition process and is used for situated dialogue.
In the experimen
