AIICS

Cyrille Berger

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2019
[19] Mariusz Wzorek, Cyrille Berger and Patrick Doherty. 2019.
Router Node Placement in Wireless Mesh Networks for Emergency Rescue Scenarios.
In PRICAI 2019: TRENDS IN ARTIFICIAL INTELLIGENCE, PT II, pages 496–509. In series: Lecture Notes in Artificial Intelligence #??. SPRINGER INTERNATIONAL PUBLISHING AG. ISBN: 978-3-030-29911-8, 978-3-030-29910-1.
DOI: 10.1007/978-3-030-29911-8_38.
Note: Funding Agencies|ELLIIT network organization for Information and Communication Technology; Swedish Foundation for Strategic ResearchSwedish Foundation for Strategic Research [RIT 15-0097]; Autonomous Systems and Software Program (WASP) - Knut and Alice Wallenberg Foundation

The focus of this paper is on base functionalities required for UAV-based rapid deployment of an ad hoc communication infrastructure in the initial phases of rescue operations. The general idea is to use heterogeneous teams of UAVs to deploy communication kits that include routers. These kits will then be used in the generation of ad hoc Wireless Mesh Networks. A fundamental problem, known as the Router Node Placement problem (RNP) is to determine how one can optimally place such routers. An extended version of the RNP problem is specified that takes into account additional constraints that arise in actual field usage. This extended problem is solved with a new algorithm, RRT-WMN, based on a novel use of the Rapidly Exploring Random Trees (RRT) algorithm used in motion planning. A comparative empirical evaluation between RRT-WMN and existing techniques, CMA-ES and PSO, shows that the RRT-WMN algorithm has far better performance both in time and coverage as the extended RNP problem scales to realistic scenarios.

2018
[18] Mariusz Wzorek, Cyrille Berger, Piotr Rudol and Patrick Doherty. 2018.
Deployment of Ad Hoc Network Nodes Using UAVs for Search and Rescue Missions.
In 2018 6TH INTERNATIONAL ELECTRICAL ENGINEERING CONGRESS (IEECON). In series: International Electrical Engineering Congress #??. IEEE. ISBN: 978-1-5386-2317-6.
DOI: 10.1109/IEECON.2018.8712230.
Note: Funding Agencies|Swedish Research Council CADICS; ELLIIT network organization for Information and Communication Technology; Swedish Foundation for Strategic Research [RIT 15-0097]

Due to the maturity of technological development, widespread use of Unmanned Aerial Vehicles (UAVs) is becoming prevalent in the civil and commercial sectors. One promising area of application is in emergency rescue support. As recently seen in a number of natural catastrophes such as the hurricanes in Texas, Florida and Puerto Rico, major communication and electrical infrastructure is knocked out, leading to an inability to communicate between the victims and rescuers on the ground as well as between rescuers themselves. This paper studies the feasibility of using heterogeneous teams of UAVs to rapidly deliver and establish ad hoc communication networks in operational environments through autonomous in-air delivery of CommKits that serve as nodes in local ad hoc networks. Hardware and software infrastructures for autonomous CommKit delivery in addition to CommKit specification and construction is considered. The results of initial evaluation of two design alternatives for CommKits are presented based on more than 25 real flight tests in different weather conditions using a commercial small-scale UAV platform.

2017
[17] Full text  Mariusz Wzorek, Cyrille Berger and Patrick Doherty. 2017.
A Framework for Safe Navigation of Unmanned Aerial Vehicles in Unknown Environments.
In 2017 25TH INTERNATIONAL CONFERENCE ON SYSTEMS ENGINEERING (ICSENG), pages 11–20. IEEE. ISBN: 978-1-5386-0610-0.
DOI: 10.1109/ICSEng.2017.58.
Note: Funding Agencies|Swedish Research Council (VR) Linnaeus Center CADICS; ELLIIT network organization for Information and Communication Technology; Swedish Foundation for Strategic Research [RIT 15-0097]

This paper presents a software framework which combines reactive collision avoidance control approach with path planning techniques for the purpose of safe navigation of multiple Unmanned Aerial Vehicles (UAVs) operating in unknown environments. The system proposed leverages advantages of using a fast local sense-and-react type control which guarantees real-time execution with computationally demanding path planning algorithms which generate globally optimal plans. A number of probabilistic path planning algorithms based on Probabilistic Roadmaps and Rapidly-Exploring Random Trees have been integrated. Additionally, the system uses a reactive controller based on Optimal Reciprocal Collision Avoidance (ORCA) for path execution and fast sense-and-avoid behavior. During the mission execution a 3D map representation of the environment is build incrementally and used for path planning. A prototype implementation on a small scale quad-rotor platform has been developed. The UAV used in the experiments was equipped with a structured-light depth sensor to obtain information about the environment in form of occupancy grid map. The system has been tested in a number of simulated missions as well as in real flights and the results of the evaluations are presented.

2016
[16] Full text  Cyrille Berger, Mariusz Wzorek, Jonas Kvarnström, Gianpaolo Conte, Patrick Doherty and Alexander Eriksson. 2016.
Area Coverage with Heterogeneous UAVs using Scan Patterns.
In 2016 IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR): proceedings. In series: 2016 IEEE INTERNATIONAL SYMPOSIUM ON SAFETY, SECURITY, AND RESCUE ROBOTICS (SSRR) #??. IEEE Robotics and Automation Society. ISBN: 978-1-5090-4349-1.
DOI: 10.1109/SSRR.2016.7784325.
fulltext:postprint: http://liu.diva-portal.org/smash/get/div...

In this paper we consider a problem of scanningan outdoor area with a team of heterogeneous Unmanned AirVehicles (UAVs) equipped with different sensors (e.g. LIDARs).Depending on the availability of the UAV platforms and themission requirements there is a need to either minimise thetotal mission time or to maximise certain properties of thescan output, such as the point cloud density. The key challengeis to divide the scanning task among UAVs while taking intoaccount the differences in capabilities between platforms andsensors. Additionally, the system should be able to ensure thatconstraints such as limit on the flight time are not violated.We present an approach that uses an optimisation techniqueto find a solution by dividing the area between platforms,generating efficient scan trajectories and selecting flight andscanning parameters, such as velocity and flight altitude. Thismethod has been extensively tested on a large set of randomlygenerated scanning missions covering a wide range of realisticscenarios as well as in real flights.

[15] Full text  Cyrille Berger, Piotr Rudol, Mariusz Wzorek and Alexander Kleiner. 2016.
Evaluation of Reactive Obstacle Avoidance Algorithms for a Quadcopter.
In Proceedings of the 14th International Conference on Control, Automation, Robotics and Vision 2016 (ICARCV). In series: International Conference on Control Automation Robotics and Vision #??. IEEE conference proceedings. ISBN: 9781509035496, 9781509047574, 9781509035502.
DOI: 10.1109/ICARCV.2016.7838803.
Note: Funding agencies:This work is partially supported by the Swedish Research Council (VR) Linnaeus Center CADICS, the ELLIIT network organization for Information and Communication Technology, and the Swedish Foundation for Strategic Research (CUAS Project, SymbiKCIoud Project).

In this work we are investigating reactive avoidance techniques which can be used on board of a small quadcopter and which do not require absolute localisation. We propose a local map representation which can be updated with proprioceptive sensors. The local map is centred around the robot and uses spherical coordinates to represent a point cloud. The local map is updated using a depth sensor, the Inertial Measurement Unit and a registration algorithm. We propose an extension of the Dynamic Window Approach to compute a velocity vector based on the current local map. We propose to use an OctoMap structure to compute a 2-pass A* which provide a path which is converted to a velocity vector. Both approaches are reactive as they only make use of local information. The algorithms were evaluated in a simulator which offers a realistic environment, both in terms of control and sensors. The results obtained were also validated by running the algorithms on a real platform.

[14] Full text  Patrick Doherty, Jonas Kvarnström, Piotr Rudol, Mariusz Wzorek, Gianpaolo Conte, Cyrille Berger, Timo Hinzmann and Thomas Stastny. 2016.
A Collaborative Framework for 3D Mapping using Unmanned Aerial Vehicles.
In Baldoni, M., Chopra, A.K., Son, T.C., Hirayama, K., Torroni, P., editors, PRIMA 2016: Principles and Practice of Multi-Agent Systems, pages 110–130. In series: Lecture Notes in Computer Science #9862. Springer Publishing Company. ISBN: 978-3-319-44831-2.
DOI: 10.1007/978-3-319-44832-9_7.
Note: Accepted for publication.

This paper describes an overview of a generic framework for collaboration among humans and multiple heterogeneous robotic systems based on the use of a formal characterization of delegation as a speech act. The system used contains a complex set of integrated software modules that include delegation managers for each platform, a task specification language for characterizing distributed tasks, a task planner, a multi-agent scan trajectory generation and region partitioning module, and a system infrastructure used to distributively instantiate any number of robotic systems and user interfaces in a collaborative team. The application focusses on 3D reconstruction in alpine environments intended to be used by alpine rescue teams. Two complex UAV systems used in the experiments are described. A fully autonomous collaborative mission executed in the Italian Alps using the framework is also described.

2014
[13] Full text  Cyrille Berger. 2014.
Strokes detection for skeletonisation of characters shapes.
In George Bebis, Richard Boyle, Bahram Parvin, Darko Koracin, Ryan McMahan, Jason Jerald, Hui Zhang, Steven M. Drucker, Chandra Kambhamettu, Maha El Choubassi, Zhigang Deng, Mark Carlson, editors, Advances in Visual Computing: 10th International Symposium, ISVC 2014, Las Vegas, NV, USA, December 8-10, 2014, Proceedings, Part II, pages 510–520. In series: Lecture Notes in Computer Science #8888. Springer. ISBN: 978-3-319-14364-4, 978-3-319-14363-7.
DOI: 10.1007/978-3-319-14364-4_49.
fulltext:postprint: http://liu.diva-portal.org/smash/get/div...

Skeletonisation is a key process in character recognition in natural images. Under the assumption that a character is made of a stroke of uniform colour, with small variation in thickness, the process of recognising characters can be decomposed in the three steps. First the image is segmented, then each segment is transformed into a set of connected strokes (skeletonisation), which are then abstracted in a descriptor that can be used to recognise the character. The main issue with skeletonisation is the sensitivity with noise, and especially, the presence of holes in the masks. In this article, a new method for the extraction of strokes is presented, which address the problem of holes in the mask and does not use any parameters.

[12] Full text  Cyrille Berger. 2014.
Colour perception graph for characters segmentation.
In George Bebis, Richard Boyle, Bahram Parvin, Darko Koracin, Ryan McMahan, Jason Jerald, Hui Zhang, Steven M. Drucker, Chandra Kambhamettu, Maha El Choubassi, Zhigang Deng, Mark Carlson, editors, Advances in Visual Computing: 10th International Symposium, ISVC 2014, Las Vegas, NV, USA, December 8-10, 2014, Proceedings, pages 598–608. In series: Lecture Notes in Computer Science #8888. Springer. ISBN: 978-3-319-14364-4, 978-3-319-14363-7.
DOI: 10.1007/978-3-319-14364-4_58.
fulltext:postprint: http://liu.diva-portal.org/smash/get/div...

Characters recognition in natural images is a challenging problem, asit involves segmenting characters of various colours on various background. Inthis article, we present a method for segmenting images that use a colour percep-tion graph. Our algorithm is inspired by graph cut segmentation techniques andit use an edge detection technique for filtering the graph before the graph-cut aswell as merging segments as a final step. We also present both qualitative andquantitative results, which show that our algorithm perform at slightly better andfaster to a state of the art algorithm.

2013
[11] Full text  Cyrille Berger. 2013.
Toward rich geometric map for SLAM: online detection of planets in 2D LIDAR.
Journal of Automation, Mobile Robotics & Intelligent Systems, 7(1):35–41.
Link to article: http://www.jamris.org/archive.php

Rich geometric models of the environment are needed for robots to carry out their missions. However a robot operating in a large environment would require a compact representation. In this article, we present a method that relies on the idea that a plane appears as a line segment in a 2D scan, and that by tracking those lines frame after frame, it is possible to estimate the parameters of that plane. The method is divided in three steps: fitting line segments on the points of the 2D scan, tracking those line segments in consecutive scan and estimating the parameters with a graph based SLAM (Simultaneous Localisation And Mapping) algorithm.

2012
[10] Full text  Cyrille Berger. 2012.
Weak Constraints Network Optimiser.
In Proceedings of the IEEE International Conference on Robotics and Automation (ICRA), pages 1270–1277. IEEE.
DOI: 10.1109/ICRA.2012.6225060.

We present a general framework to estimate the parameters of both a robot and landmarks in 3D. It relies on the use of a stochastic gradient descent method for the optimisation of the nodes in a graph of weak constraints where the landmarks and robot poses are the nodes. Then a belief propagation method combined with covariance intersection is used to estimate the uncertainties of the nodes. The first part of the article describes what is needed to define a constraint and a node models, how those models are used to update the parameters and the uncertainties of the nodes. The second part present the models used for robot poses and interest points, as well as simulation results.

[9] Full text  Cyrille Berger. 2012.
Toward rich geometric map for SLAM: Online Detection of Planes in 2D LIDAR.
In Proceedings of the International Workshop on Perception for Mobile Robots Autonomy (PEMRA).
fulltext:postprint: http://liu.diva-portal.org/smash/get/div...

Rich geometric models of the environment are needed for robots to accomplish their missions. However a robot operatingin a large environment would require a compact representation.In this article, we present a method that relies on the idea that a plane appears as a line segment in a 2D scan, andthat by tracking those lines frame after frame, it is possible to estimate the parameters of that plane. The method istherefore divided in three steps: fitting line segments on the points of the 2D scan, tracking those line segments inconsecutive scan and estimating the parameters with a graph based SLAM (Simultaneous Localisation And Mapping)algorithm.

2011
[8] Full text  Teresa Vidal-Calleja, Cyrille Berger, Joan Solà and Simon Lacroix. 2011.
Large scale multiple robot visual mapping with heterogeneous landmarks in semi-structured terrain.
Robotics and Autonomous Systems, 59(9):654–674. Elsevier.
DOI: 10.1016/j.robot.2011.05.008.

This paper addresses the cooperative localization and visual mapping problem with multiple heterogeneous robots. The approach is designed to deal with the challenging large semi-structured outdoors environments in which aerial/ground ensembles are to evolve. We propose the use of heterogeneous visual landmarks, points and line segments, to achieve effective cooperation in such environments. A large-scale SLAM algorithm is generalized to handle multiple robots, in which a global graph maintains the relative relationships between a series of local sub-maps built by the different robots. The key issue when dealing with multiple robots is to find the link between them, and to integrate these relations to maintain the overall geometric consistency; the events that introduce these links on the global graph are described in detail. Monocular cameras are considered as the primary extereoceptive sensor. In order to achieve the undelayed initialization required by the bearing-only observations, the well-known inverse-depth parametrization is adopted to estimate 3D points. Similarly, to estimate 3D line segments, we present a novel parametrization based on anchored Plücker coordinates, to which extensible endpoints are added. Extensive simulations show the proposed developments, and the overall approach is illustrated using real-data taken with a helicopter and a ground rover.

2010
[7] Full text  Cyrille Berger and Simon Lacroix. 2010.
DSeg: Détection directe de segments dans une image.
In 17ème congrès francophone AFRIF-AFIA Reconnaissance des Formes et Intelligence Artificielle (RFIA).

Cet article présente une approche ``model-driven'' pour détecter des segmentsde droite dans une image. L'approche détecte les segments de manièreincrémentale sur la base du gradient de l'image, en exploitant un filtre deKalman linéaire qui estime les paramètres de la droite support des segments etles variances associées. Les algorithmes sont rapides et robustes au bruit etaux variations d'illumination de la scène perçue, ils permettent de détecterdes segments plus longs que les approches existantes guidées par les données(``data-driven''), et ils ne nécessitent pas de délicate détermination deparamètres. Des résultats avec différentes conditions d'éclairage et descomparaisons avec les approches existantes sont présentés.

2009
[6] Full text  Cyrille Berger. 2009.
Perception de la géométrie de l'environment pour la navigation autonome.
PhD Thesis. Université de Toulouse. 164 pages.

Le but de la recherche en robotique mobile est de donner aux robots la capacité d'accomplir des missions dans un environnement qui n'est pas parfaitement connu. Mission, qui consiste en l'exécution d'un certain nombre d'actions élémentaires (déplacement, manipulation d'objets...) et qui nécessite une localisation précise, ainsi que la construction d'un bon modèle géométrique de l'environnement, a partir de l'exploitation de ses propres capteurs, des capteurs externes, de l'information provenant d'autres robots et de modèle existant, par exemple d'un système d'information géographique. L'information commune est la géométrie de l'environnement. La première partie du manuscrit couvre les différentes méthodes d'extraction de l'information géométrique. La seconde partie présente la création d'un modèle géométrique en utilisant un graphe, ainsi qu'une méthode pour extraire de l'information du graphe et permettre au robot de se localiser dans l'environnement.

[5] Full text  Teresa Vidal-Calleja, Cyrille Berger, Joan Solà and Simon Lacroix. 2009.
Environment Modeling for Cooperative Aerial/Ground Robotic Systems.
In Proceedings of the 14th International Symposium on Robotics Research (ISRR), pages 681–696. In series: Springer Tracts in Advanced Robotics #70. Springer. ISBN: 978-3-642-19456-6.
DOI: 10.1007/978-3-642-19457-3_40.

This paper addresses the cooperative localization and visual mapping problem for multiple aerial and ground robots.We propose the use of heterogeneous visual landmarks, points and line segments. A large-scale SLAM algorithm is generalized to manage multiple robots, in which a global graph maintains the topological relationships between a series of local sub-maps built by the different robots. Only single camera setups are considered: in order to achieve undelayed initialization, we present a novel parametrization for lines based on anchored Plücker coordinates, to which we add extensible endpoints to enhance their representativeness. The built maps combine such lines with 3D points parametrized in inverse-depth. The overall approach is evaluated with real-data taken with a helicopter and a ground rover in an abandoned village.

[4] Full text  Teresa Vidal-Calleja, Cyrille Berger and Simon Lacroix. 2009.
Event-driven loop closure in multi-robot mapping.
In Proceedings of the IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), pages 1535–1540. IEEE conference proceedings. ISBN: 978-1-4244-3803-7.
DOI: 10.1109/IROS.2009.5354335.

A large-scale mapping approach is combined with multiple robots events to achieve cooperative mapping. The mapping approach used is based on hierarchical SLAM -global level and local maps-, which is generalized for the multi-robot case. In particular, the consequences of multi-robot loop closing events (common landmarks detection and relative pose measurement between robots) are analyzed and managed at a global level. We present simulation results for each of these events using aerial and ground robots, and experimental results obtained with ground robots.

2008
[3] Full text  Cyrille Berger and Simon Lacroix. 2008.
Modélisation de l'environnement par facettes planes pour la Cartographie et la Localisation Simultanées par stéréovision.
In Reconnaissance des Formes et Intelligence Artificielle (RFIA).

[2] Full text  Cyrille Berger and Simon Lacroix. 2008.
Using planar facets for stereovision SLAM.
In Proceedings of the IEEE/RSJ International Conference on Intelligent RObots and Systems (IROS), pages 1606–1611. IEEE conference proceedings. ISBN: 978-1-4244-2057-5.
DOI: 10.1109/IROS.2008.4650986.

In the context of stereovision SLAM, we propose a way to enrich the landmark models. Vision-based SLAM approaches usually rely on interest points associated to a point in the Cartesian space: by adjoining oriented planar patches (if they are present in the environment), we augment the landmark description with an oriented frame. Thanks to this additional information, the robot pose is fully observable with the perception of a single landmark, and the knowledge of the patches orientation helps the matching of landmarks. The paper depicts the chosen landmark model, the way to extract and match them, and presents some SLAM results obtained with such landmarks.

2007
[1] Full text  Thomas Lemaire, Cyrille Berger, Il-Kyun Jung and Simon Lacroix. 2007.
Vision-Based SLAM: Stereo and Monocular Approaches.
International Journal of Computer Vision, 74(3):343–364. Kluwer Academic Publishers.
DOI: 10.1007/s11263-007-0042-3.

Building a spatially consistent model is a key functionality to endow a mobile robot with autonomy. Without an initial map or an absolute localization means, it requires to concurrently solve the localization and mapping problems. For this purpose, vision is a powerful sensor, because it provides data from which stable features can be extracted and matched as the robot moves. But it does not directly provide 3D information, which is a difficulty for estimating the geometry of the environment. This article presents two approaches to the SLAM problem using vision: one with stereovision, and one with monocular images. Both approaches rely on a robust interest point matching algorithm that works in very diverse environments. The stereovision based approach is a classic SLAM implementation, whereas the monocular approach introduces a new way to initialize landmarks. Both approaches are analyzed and compared with extensive experimental results, with a rover and a blimp.