[1]
H.
Baltzakis, A. A. Argyros, P.E. Trahanias, Fusion of Range and Visual Data for the
Extraction of Scene Structure Information,
International Conference on Pattern Recognition, ICPR'02, Quebec
(Canada),
August 11-15, 2002.
Abstract: In
this paper, a method for inferring 3D structure information based on
both range
and visual data is proposed. Data fusion is achieved by validating
assumptions
formed according to 2D range scans of the environment, through the
exploitation
of visual information. The proposed method is readily applicable to
robot
navigation tasks providing significant advantages over existing
methods.
(Full text in
pdf
format)
[2] H.
Baltzakis, P.E. Trahanias, Closing
Multiple Loops while Mapping Features in Cyclic Environments,
IEEE/RSJ
International. Conf. On Intelligent Robots and Systems, IROS 2003,
pp.717-722,
Las Vegas (USA), Oct. 27-31, 2003.
Abstract: In
this paper we propose an offline feature-mapping algorithm capable of
identifying
and correctly closing multiple loops in cyclic environments (see
video). The
proposed algorithm iteratively alternates between a Kalman smoother
based localization
step and a map features recalculation step. The identification of loops
is done
during the localization step by a hybrid localization algorithm that
generates
and tracks hypotheses generated each time the robot visits an already
mapped
area. The main contribution of this paper lies on the ability of the
proposed
algorithm to exploit information contained within the hypotheses
histories in
order to calculate correct maps, regardless of the complexity of the
environment
and the number of loops in the robot’s path.
(Full text in pdf
format)
[3] W.
Burgard, P. Trahanias, D. Hähnel, M.
Moors, D. Schulz, H. Baltzakis, A. Argyros, TOURBOT and WebFAIR:
Web-Operated Mobile Robots for Tele-Presence in Populated Exhibitions,
Workshop on Robots in Exhibitions 2002, IEEE/RSJ International Conf. on
Intelligent Robots and Systems, IROS 2002, Lausanne (Switzerland), 2002
Abstract: The
current paper presents techniques that facilitate mobile robots to be
deployed
as interactive agents in populated environments, such as museum
exhibitions or
trade shows. The mobile robots can be tele-operated over the Internet
and this
way provide remote access to distant users. Throughout this paper we
describe
several key techniques that have been developed in the relevant
projects. They
include robust mapping and localization, people-tracking and advanced
visualizations for Web users. The developed robotic systems have been
installed
and operated in the premises of various sites. Use of the above
techniques, as
well as appropriate authoring tools, has resulted in drastic reduction
in the
installation times. Additionally, the systems were thoroughly tested
and validated
in real-world conditions. Such demonstrations ascertain the
functionality and
reliability of our methods and provide evidence as of the operation of
the
complete systems.
(Full text in pdf
format)
[4] A.
Foka, P.E. Trahanias, Predictive
Autonomous Robot Navigation, IEEE/RSJ Intl. Conf. on Intelligent
Robots
and
Systems, IROS 2002, pp. 490-495, Lausanne (Switzerland), Sep.30-Oct.4,
2002.
Abstract: This
paper considers the problem of a robot navigating in a crowded or
congested
environment. A robot operating in such an environment can get easily
blocked by
moving humans and other objects. To deal with this problem it is
proposed to
attempt to predict the motion trajectory of humans and obstacles. Two
kinds of
prediction are considered: short-term and long-term. The short-term
prediction
refers to the one-step ahead prediction and the long-term to the
prediction of
the final destination point of the obstacle's movement. The robot
movement is
controlled by a Partially Observable Markov Decision Process (POMDP).
POMDPs
are utilized because of their ability to model information about the
robot's
location and sensory information in a probabilistic manner. The
solution of a
POMDP is computationally expensive and thus a hierarchical
representation of
POMDPs is used.
(Full text in pdf
format)
[5] A.
Foka, P.E. Trahanias, Predictive
Control of Robot Velocity for Obstacle Avoidance in Dynamic
Environments,
IEEE/RSJ International Conf. on Intelligent Robots and Systems, IROS
2003,
pp.370-375, Las Vegas (USA), Oct. 27-31, 2003.
Abstract: This
paper introduces a methodology for avoiding obstacles by controlling
the
robot’s velocity. Contemporary approaches to obstacle avoidance usually
dictate
a detour from the originally planned trajectory to its goal position.
In our
previous work, we presented a method for predicting the motion of
obstacles,
and how to make use of this prediction when planning the robot
trajectory to
its goal position. This is extended in the current paper by also using
this
prediction to decide if the robot should change its speed to avoid an
obstacle
more effectively. The robot can choose to move at three different
speeds: slow,
normal and fast. The robot movement is controlled by a Hierarchical
Partially
Observable Markov Decision Process (POMDP). The POMDP formulation is
not
altered to accommodate for the three different speeds, to avoid the
increase of
the size of the state space. Instead, a
modified solution of POMDPs is used.
(Full text in pdf
format)
[6] D.
Hähnel, D. Schulz, W. Burgard, Map
Building with Mobile Robots in Populated Environments,
International
Conference on Intelligent Robots and Systems, IROS 2002.
Abstract: The
problem of generating maps with mobile robots has received considerable
attention
over the past years. However, most of the approaches assume that the
environment is static during the data-acquisition phase. In this paper
we
consider the problem of creating maps with mobile robots in populated
environments. Our approach uses a probabilistic method to track
multiple people
and to incorporate the results of the tracking technique into the
mapping process. The resulting maps are
more accurate since corrupted readings are treated accordingly during
the
matching phase and since the number of spurious objects in the
resulting maps
is reduced. Our approach has been implemented and tested on real robot
systems
in indoor and outdoor scenarios. We present several experiments
illustrating
the capabilities of our approach to generate accurate 2d and 3d
maps.
(Full text in pdf
format)
[7] D.
Hähnel, R. Triebel, W. Burgard, S.
Thrun, Map Building with Mobile
Robots in Dynamic Environments. IEEE
International Conference on Robotics and Automation, ICRA 2003.
Abstract: The
problem of generating maps with mobile robots has received considerable
attention over the past years. Most of the techniques developed so far
have
been designed for situations in which the environment is static during
the
mapping process. Dynamic objects, however, can lead to serious errors
in the
resulting maps such as spurious objects or misalignments due to
localization
errors. In this paper we consider the problem of creating maps with
mobile
robots in dynamic environments. We present a new approach that
interleaves
mapping and localization with a probabilistic technique to identify
spurious
measurements. In several experiments we demonstrate that our algorithm
generates accurate 2d and 3d in different kinds of dynamic indoor and
outdoor
environments. We also use our algorithm to isolate the dynamic objects
and to
generate three-dimensional representation of them.
(Full text in pdf
format)
[8] D.
Hähnel, D. Fox, W. Burgard, S. Thrun, A
highly efficient FastSLAM algorithm for generating cyclic maps of
large-scale
environments from raw laser range measurements, International
Conference on
Intelligent Robots and Systems, IROS 2003.
Abstract: The ability to learn a consistent
model of its environment is a prerequisite for autonomous mobile
robots. A
particularly challenging problem in acquiring environment maps is that
of
closing loops; loops in the environment create challenging data
association
problems [9]. This paper presents a novel algorithm that combines
Rao-Blackwellized particle filtering and scan matching. In our approach
scan
matching is used for minimizing odometric errors during mapping. A
probabilistic
model of the residual errors of scan matching process is then used for
the
resampling steps. This way the number
of samples required is seriously reduced. Simultaneously we reduce the
particle
depletion problem that typically prevents the robot from closing large
loops.
We present extensive experiments that illustrate the superior
performance of
our approach compared to previous approaches.
(Full text pdf
format)
[9] D.
Hähnel, W. Burgard, D. Fox, K.
Fishkin, M.
Philipose, Mapping and Localization
with RFID Technology, IEEE
International Conference on Robotics and
Automation, ICRA 2004.
Abstract: In
this paper we analyze whether recent Radio Frequency Identification
(RFID)
technology can be used to improve the localization of mobile robots and
persons
in their environment. In particular we study the problem of localizing
RFID
tags with a mobile platform that is equipped with a pair of RFID
antennas. We
present a probabilistic measurement model for RFID readers that allow
us to
accurately localize RFID tags in the environment. We also demonstrate
how such
maps can be used to localize a robot and persons in their environment.
Finally,
we present experiments illustrating that the computational requirements
for
global robot localization can be reduced strongly by fusing RFID
information
with laser data.
(Full text in pdf
format)
[10] D. Rodriguez-Losada,
F.
Matia, R. Galan, A. Jimenez, Blacky,
an Interactive Mobile Robot at a
Trade Fair, IEEE
International Conf. On Robotics and Automation, ICRA’2002, Washington,
DC (USA), 11-15, May, 2002.
Abstract: This
paper presents the first approach towards the main goal of developing a
completely autonomous robot that serves as a local and remote guide at
a trade
fair. Innovative solutions
are provided to solve several problems found in this environment.
Reactive-perceptual behaviors are executed to provide motion while a
low level
controller avoids collisions. A virtual corridor map, simulated
perception, and
an Extended Kalman Filter for localization, are used to overcome the
lack of perception.
Voice synthesizing is provided to be an effective aid for navigation,
as well
as for the overall success and acceptance of the system. A Denning Mrv4
robot
called Blacky was used to carry out experiments in actual environments
on three
occasions, and the obtained conclusions sound promising for future
research.
(Full text in pdf
format)
[11] D.
Rodriguez-Losada, F. Matia, Integrating
Segments and Edges in Feature-based SLAM, IEEE 11th
International
Conference on Advanced Robotics, ICAR 2003, Coimbra (Portugal), June 30
–July
3, 2003.
Abstract: In
this paper a new framework for integrating edge information into
segments in
feature based SLAM, with minimum system overloading, is presented. All
operations required for building and maintaining this map are described
and
formulated. A whole implementation of this approach has been
programmed,
optimized and successfully tested in several indoor environments with
different
mobile robots.
(Full text in pdf
format)
[12] D.
Rodriguez-Losada, F. Matia, Local
Maps Fusion for Real Time Multirobot Indoor Simultaneous Localization
and
Mapping, IEEE International Conf. On Robotics and Automation,
ICRA’2004,
New Orleans, LA (USA), April 26 – May 1, 2004.
Abstract: This
paper presents an implementation of the Local Maps Fusion concept for
the
Simultaneous Localization and Mapping (SLAM) problem within the
Extended Kalman
Filter (EKF) framework. Several problems never addressed before, arise
while
implementing the solution for indoor environments, and are successfully
solved
to obtain maps of quite large real indoor environments with more than
one robot
in real time.
(Full text in pdf
format)
[13] F.
Matia, D. Rodriquez-Losada, R.
Galan, A. Jimenez, Experiments at
Trade Fairs with Blacky the Robot,
IROS 2002, Workshop “Robots in Exhibitions”, Lausanne (Switzerland),
Sept. 30 –
Oct. 4, 2002.
Abstract: Blacky
has been tested in exhibition-like contests, more precisely, in two
trade fairs
and one competition event. Presently, its main task is as tour-guide
and
entertainment, making an special emphasis in artificial intelligence
techniques
for human-robot interaction capabilities, a crucial point for robot
acceptance
by humans. The robot has really worked in long-term experiments, where
system
integration and safety issues have been taken into account. The
navigation
algorithms, as well as the lessons learnt, are described in the paper,
focussing on robot movements in an indoor, populated, complex and low
structured environment. The market point of view is also analysed with
the help
of an exhibition organizer.
(Full text in pdf
format)
[14] F.
Matia, A. Jimenez, D.
Rodriguez-Losada, B. M. Al-Hadithi, A
Novel Fuzzy Kalman Filter for
Mobile
Robots Localization, IPMU’2004, Perugia (Italia), 4-9 July, 2004.
Abstract: A
new method to implement fuzzy Kalman filters is introduced in this
paper. This
has special application in fields where inaccurate models or sensors
are
involved, such as in mobile robotics. The innovation consists in using
possibility distributions, instead of gaussian distributions. The main
advantage of this approach is that uncertainty is not needed to be
symmetric,
while a region of possible solutions is allowed. The contribution of
this work
also includes a method to propagate uncertainty through both the
process and the observation models. This
one is based on quantifying uncertainty as trapezoidal possibility
distributions. Finally, the way to reduce the EKF inconsistence when
large
number of iterations are carried out is shown.
(Full text in pdf
format)
[15] C.
Stachniss, W. Burgard, An Integrated
Approach to Goal-directed Obstacle Avoidance under Dynamic Constraints
for
Dynamic Environments, IEEE/RSJ International Conference on
Intelligent
Robots and Systems, IROS 2002.
Abstract: Whenever
robots are installed in populated environments, they need appropriate
techniques to avoid collisions with unexpected obstacles. Over the past
years
several reactive techniques have been developed that use heuristic
evaluation
functions to choose appropriate actions whenever a robot encounters an
unforeseen
obstacle. Whereas the majority of these approaches determines only the
next
steering command, some additionally consider sequences of possible
poses.
However, they generally do not consider sequences of actions in the
velocity
space. Accordingly, these methods are not able to slow down the robot
early
enough before it has to enter a narrow passage. In this paper we
present a new
approach that integrates path planning with sensor-based collision
avoidance.
Our algorithm simultaneously considers the robot’s pose and velocities
during
the planning process. We employ different strategies to deal with the
huge
state space that has to be explored. Our method has been implemented
and tested
on real robots and in simulation runs. Extensive experiments
demonstrate that
our technique can reliably control mobile robots moving at high speeds.
(Full text in pdf
format)
[16] C.
Stachniss, W. Burgard, Mapping and
Exploration with Mobile Robots using Coverage Maps, IEEE/RSJ
International
Conference on Intelligent Robots and Systems, IROS 2003.
Abstract: Exploration
and mapping belongs to the fundamental tasks of mobile robots. In the
past,
many approaches have used occupancy grid maps to represent the
environment
during the map building process. Occupancy grids, however, are based on
the
assumption that each cell is either occupied or free. In this paper we
introduce coverage maps as an alternative way of representing the
environment
of a robot. Coverage maps store for each cell of a given grid a
posterior about
the amount the corresponding cell is covered by an obstacle. We also
present a
model that allows us to update coverage maps upon input obtained from
proximity
sensors. We furthermore describe how to use coverage maps for a
decision
theoretic approach to exploration. Finally we present experimental
results
illustrating that coverage maps can be used to efficiently learn highly
accurate models even if noisy sensors such as ultrasounds are used.
(Full text in pdf
format)
[17] P.E.
Trahanias, W. Burgard, D.
Haehnel, M. Moors, D. Schulz, H. Baltzakis, A. Argyros, Tele-Presence
in
Populated Exhibitions through Web-operated Robots, invited
contribution,
Robotics and Art special session, 11th Intl. Conf. on Advanced
Robotics, ICAR
2003, pp.1253-1258, Coimbra (Portugal), June 30 - July 3, 2003.
Abstract: The
current paper presents techniques that facilitate mobile robots to be
deployed
as interactive agents in populated environments, such as museum
exhibitions or
trade shows. The mobile robots can be teleoperated over the Internet
and this
way provide remote access to distant users. Throughout this paper we
describe
several key techniques that have been developed in the context of
relevant
EU-IST projects. The developed robotic systems have been installed and
extensively operated in the premises of various sites. The use of the
above techniques,
combined with appropriate authoring tools, has resulted in drastic
reduction in
the installation times. Such demonstrations ascertain the functionality
and
reliability of our methods and provide evidence regarding the
effectiveness of
the complete systems.
(Full text in pdf
format)
[18] H.
Baltzakis, P.E. Trahanias, A Hybrid
Framework for Mobile Robot
Localization:
Formulation Using Switching State-Space Models, Autonomous
Robots Journal 15 (2), pp. 169-191, 2003.
Abstract: In
this paper we address one of the most important issues for autonomous
mobile
robots, namely their ability to localize themselves safely and reliably
within
their environments. We propose a probabilistic framework for modeling
the robot’s
state and sensory information based on a Switching State-Space Model.
The
proposed framework generalizes two of the most successful probabilistic
model
families currently used for this purpose: the Kalman filter linear
models and
the Hidden Markov Models. The proposed model combines the advantages of
both
models, relaxing at the same time inherent assumptions made
individually in
each of these existing models.
(Full text in pdf
format)
[19] W.
Burgard, P.E. Trahanias, D. Haehnel, M.
Moors, D. Schulz, H. Baltzakis, A. Argyros, Tele-presence in Populated
Exhibitions through Web-operated Mobile Robots, special issue on
On-line
Robots, Autonomous Robots Journal 15 (3), pp. 299-316, 2003.
Abstract: This
paper presents techniques that facilitate mobile robots to be deployed
as
interactive agents in populated environments such as museum exhibitions
or
trade shows. The mobile robots can be tele-operated over the Internet
and, this
way, provide remote access to distant users. Throughout this paper we
describe
several key techniques that have been developed in this context. To
support
safe and reliable robot navigation, techniques for environment mapping,
robot
localization, obstacle detection and people-tracking have been
developed. To
support the interaction of both web and on-site visitors with the robot
and its
environment, appropriate software and hardware interfaces have been
employed.
By using advanced navigation capabilities and appropriate authoring
tools, the
time required for installing a robotic tour-guide in a museum or a
trade fair
has been drastically reduced. The developed robotic systems have been
thoroughly tested and validated in the real-world conditions offered in
the
premises of various sites. Such demonstrations ascertain the
functionality of
the employed techniques, establish the reliability of the complete
systems, and
provide useful evidence regarding the acceptance of tele-operated
robotic
tour-guides by the broader public.
(Full text in pdf
format)
[20] D. Hähnel,
D.
Schulz, W. Burgard, Mobile
Robot Mapping in Populated Environments, Advanced Robotics 17
(7),
pp.579-598, 2003.
Abstract: The
problem of learning maps with mobile robots has received considerable
attention
over the past years. Most of the approaches, however, assume that the
environment is static during the data-acquisition phase. In this paper
we
consider the problem of creating maps with mobile robots in populated
environments.
Our approach uses a probabilistic method to track multiple people and
to
incorporate the estimates of the tracking technique into the mapping
process.
The resulting maps are more accurate since the number of spurious
objects is
reduced and since the robustness of range registration is improved. Our
approach has been implemented and tested on real robots in indoor and
outdoor
scenarios. We present several experiments illustrating the capabilities
of our
approach to generate accurate 2d and 3d maps.
(Full text in pdf
format)
For more details email to: webfair@ics.forth.gr