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  • 401. Shokoufandeh, Ali
    et al.
    Dickinson, Sven Josef
    Jönsson, Clas
    KTH, Tidigare Institutioner, Numerisk analys och datalogi, NADA.
    On the representation and matching of qualitative shape at multiple scales2002Ingår i: ECCV '02: Proceedings of the 7th European Conference on Computer Vision, 2002, Vol. 2352, s. 759-775Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present a framework for representing and matching multi-scale, qualitative feature hierarchies. The coarse shape of an object is captured by a set of blobs and ridges, representing compact and elongated parts of an object. These parts, in turn, map to nodes in a directed acyclic graph, in which parent/child edges represent feature overlap, sibling edges join nodes with shared parents, and all edges encode geometric relations between the features. Given two feature hierarchies, represented as directed acyclic graphs, we present an algorithm for computing both similarity and node correspondence in the presence of noise and occlusion. Similarity, in turn, is a function of structural similarity, contextual similarity (geometric relations among neighboring nodes), and node contents similarity. Moreover, the weights of these components can be varied on a node by node basis, allowing a graph-based model to effectively parameterize the saliency of its constraints. We demonstrate the approach on two domains: gesture recognition and face detection.

  • 402. Shokoufandeh, Ali
    et al.
    Dickinson, Sven
    Jönsson, Clas
    Bretzner, Lars
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Lindeberg, Tony
    KTH, Tidigare Institutioner, Numerisk analys och datalogi, NADA.
    On the Representation and Matching of Qualitative Shape at Multiple Scales2002Ingår i: Computer Vision — ECCV 2002: 7th European Conference on Computer Vision Copenhagen, Denmark, May 28–31, 2002 Proceedings, Part III, Springer Berlin/Heidelberg, 2002, s. 759-775Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present a framework for representing and matching multi-scale, qualitative feature hierarchies. The coarse shape of an object is captured by a set of blobs and ridges, representing compact and elongated parts of an object. These parts, in turn, map to nodes in a directed acyclic graph, in which parent/child edges represent feature overlap, sibling edges join nodes with shared parents, and all edges encode geometric relations between the features. Given two feature hierarchies, represented as directed acyclic graphs, we present an algorithm for computing both similarity and node correspondence in the presence of noise and occlusion. Similarity, in turn, is a function of structural similarity, contextual similarity (geometric relations among neighboring nodes), and node contents similarity. Moreover, the weights of these components can be varied on a node by node basis, allowing a graph-based model to effectively parameterize the saliency of its constraints. We demonstrate the approach on two domains: gesture recognition and face detection.

  • 403.
    Siadat, Medya
    et al.
    Azarbaijan Shahid Madani Univ, Dept Appl Math, Tabriz 5375171379, Iran..
    Aghazadeh, Nasser
    Azarbaijan Shahid Madani Univ, Dept Appl Math, Tabriz 5375171379, Iran..
    Akbarifard, Farideh
    Azarbaijan Shahid Madani Univ, Dept Appl Math, Tabriz 5375171379, Iran..
    Brismar, Hjalmar
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biofysik. KTH, Centra, Science for Life Laboratory, SciLifeLab. SciLifeLab, Adv Light Microscopy Facil, S-17165 Solna, Sweden..
    Öktem, Ozan
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Matematik (Avd.). KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Joint Image Deconvolution and Separation Using Mixed Dictionaries2019Ingår i: IEEE Transactions on Image Processing, ISSN 1057-7149, E-ISSN 1941-0042, Vol. 28, nr 8, s. 3936-3945Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The task of separating an image into distinct components that represent different features plays an important role in many applications. Traditionally, such separation techniques are applied once the image in question has been reconstructed from measured data. We propose an efficient iterative algorithm, where reconstruction is performed jointly with the task of separation. A key assumption is that the image components have different sparse representations. The algorithm is based on a scheme that minimizes a functional composed of a data discrepancy term and the l(1)-norm of the coefficients of the different components with respect to their corresponding dictionaries. The performance is demonstrated for joint 2D deconvolution and separation into curve- and point-like components, and tests are performed on synthetic data as well as experimental stimulated emission depletion and confocal microscopy data. Experiments show that such a joint approach outperforms a sequential approach, where one first deconvolves data and then applies image separation.

  • 404.
    Sibirtseva, Elena
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Robotik, perception och lärande, RPL.
    Ghadirzadeh, Ali
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Robotik, perception och lärande, RPL. Intelligent Robotics Research Group, Aalto University, Espoo, Finland.
    Leite, Iolanda
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Robotik, perception och lärande, RPL.
    Björkman, Mårten
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Robotik, perception och lärande, RPL.
    Kragic, Danica
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Robotik, perception och lärande, RPL.
    Exploring Temporal Dependencies in Multimodal Referring Expressions with Mixed Reality2019Ingår i: Virtual, Augmented and Mixed Reality. Multimodal Interaction 11th International Conference, VAMR 2019, Held as Part of the 21st HCI International Conference, HCII 2019, Orlando, FL, USA, July 26–31, 2019, Proceedings, Springer Verlag , 2019, s. 108-123Konferensbidrag (Refereegranskat)
    Abstract [en]

    In collaborative tasks, people rely both on verbal and non-verbal cues simultaneously to communicate with each other. For human-robot interaction to run smoothly and naturally, a robot should be equipped with the ability to robustly disambiguate referring expressions. In this work, we propose a model that can disambiguate multimodal fetching requests using modalities such as head movements, hand gestures, and speech. We analysed the acquired data from mixed reality experiments and formulated a hypothesis that modelling temporal dependencies of events in these three modalities increases the model’s predictive power. We evaluated our model on a Bayesian framework to interpret referring expressions with and without exploiting the temporal prior.

  • 405. Siozios, K.
    et al.
    Diamantopoulos, D.
    Kostavelis, Ioannis
    Production and Management Engineering Dept., Democritus University of Thrace, Greece.
    Boukas, Evangelos
    Production and Management Engineering Dept., Democritus University of Thrace, Greece.
    Nalpantidis, Lazaros
    Production and Management Engineering Dept., Democritus University of Thrace, Greece.
    Soudris, D.
    Gasteratos, Antonios
    Production and Management Engineering Dept., Democritus University of Thrace, Greece.
    Aviles, M.
    Anagnostopoulos, I.
    SPARTAN project: Efficient implementation of computer vision algorithms onto reconfigurable platform targeting to space applications2011Ingår i: 6th International Workshop on Reconfigurable Communication-Centric Systems-on-Chip, ReCoSoC 2011 - Proceedings, 2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    Vision-based robotic applications exhibit increased computational complexity. This problem becomes even more important regarding mission critical application domains. The SPARTAN project focuses in the tight and optimal implementation of computer vision algorithms targeting to rover navigation for space applications. For evaluation purposes, these algorithms will be implemented with a co-design methodology onto a Virtex-6 FPGA device.

  • 406.
    Sjöholm, Daniel
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Calibration using a general homogeneous depth camera model2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Att noggrant kunna mäta avstånd i djupbilder är viktigt för att kunna göra bra rekonstruktioner av objekt. Men denna mätprocess är brusig och dagens djupsensorer tjänar på ytterligare korrektion efter fabrikskalibrering. Vi betraktar paret av en djupsensor och en bildsensor som en enda enhet som returnerar komplett 3D information. 3D informationen byggs upp från de två sensorerna genom att lita på den mer precisa bildsensorn för allt förutom djupmätningen. Vi presenterar en ny linjär metod för att korrigera djupdistorsion med hjälp av en empirisk modell, baserad kring att enbart förändra djupdatan medan plana ytor behålls plana. Djupdistortionsmodellen implementerades och testades på kameratypen Intel RealSense SR300. Resultaten visar att modellen fungerar och i regel minskar mätfelet i djupled efter kalibrering, med en genomsnittlig förbättring kring 50 procent för de testade dataseten.

  • 407.
    Sjöö, Kristoffer
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Zender, Hendrik
    Jensfelt, Patric
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Kruijff, Geert-Jan M.
    Pronobis, Andrzej
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Hawes, Nick
    Brenner, Michael
    The explorer system2010Ingår i: Cognitive Systems Monographs: Cognitive Systems / [ed] H. I. Christensen, G.-J. M. Kruijff, J. L. Wyatt, Springer Berlin/Heidelberg, 2010, 8, s. 395-421Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    In the Explorer scenario we deal with the problems of modeling space, acting in this space and reasoning about it. Spatial models are built using input from sensors such as laser scanners and cameras but equally importantly also based on human input. It is this combination that enables the creation of a spatial model that can support low level tasks such as navigation, as well as interaction. Even combined, the inputs only provide a partial description of the world. By combining this knowledge with a reasoning system and a common sense ontology, further information can be inferred to make the description of the world more complete. Unlike the PlayMate system, all the information that is needed to build the spatial models are not available to it sensors at all times. The Explorer need to move around, i.e. explorer space, to gather information and integrate this into the spatial models. Two main modes for this exploration of space have been investigated within the Explorer scenario. In the first mode the robot explores space together with a user in a home tour fashion. That is, the user shows the robot around their shared environment. This is what we call the Human Augmented Mapping paradigm. The second mode is fully autonomous exploration where the robot moves with the purpose of covering space. In practice the two modes would both be used interchangeably to get the best trade-off between autonomy, shared representation and speed. The focus in the Explorer is not on performing a particular task to perfection, but rather acting within a flexible framework that alleviates the need for scripting and hardwiring. We want to investigate two problems within this context: what information must be exchanged by different parts of the system to make this possible, and how the current state of the world should be represented during such exchanges. One particular interaction which encompasses a lot of the aforementioned issues is giving the robot the ability to talk about space. This interaction raises questions such as:  how can we design models that allow the robot and human to talk about where things are, and how do we link the dialogue and the mapping systems?

  • 408.
    Staniaszek, Michal
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Feature-Feature Matching For Object Retrieval in Point Clouds2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In this project, we implement a system for retrieving instances of objects from point clouds using feature based matching techniques. The target dataset of point clouds consists of approximately 80 full scans of office rooms over a period of one month. The raw clouds are reprocessed to remove regions which are unlikely to contain objects. Using locations determined by one of several possible interest point selection methods, one of a number of descriptors is extracted from the processed clouds. Descriptors from a target cloud are compared to those from a query object using a nearest neighbour approach. The nearest neighbours of each descriptor in the query cloud are used to vote for the position of the object in a 3D grid overlaid on the room cloud. We apply clustering in the voting space and rank the clusters according to the number of votes they contain. The centroid of each of the clusters is used to extract a region from the target cloud which, in the ideal case, corresponds to the query object. We perform an experimental evaluation of the system using various parameter settings in order to investigate factors affecting the usability of the system, and the efficacy of the system in retrieving correct objects. In the best case, we retrieve approximately 50% of the matching objects in the dataset. In the worst case, we retrieve only 10%. We find that the best approach is to use a uniform sampling over the room clouds, and to use a descriptor which factors in both colour and shape information to describe points.

  • 409.
    Stefanov, Kalin
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Tal, musik och hörsel, TMH, Tal-kommunikation.
    Beskow, Jonas
    KTH, Skolan för datavetenskap och kommunikation (CSC), Tal, musik och hörsel, TMH, Tal-kommunikation.
    Salvi, Giampiero
    KTH, Skolan för datavetenskap och kommunikation (CSC), Tal, musik och hörsel, TMH.
    Vision-based Active Speaker Detection in Multiparty Interaction2017Ingår i: Grounding Language Understanding, 2017Konferensbidrag (Refereegranskat)
  • 410.
    Stefanov, Kalin
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Tal, musik och hörsel, TMH.
    Salvi, Giampiero
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Tal, musik och hörsel, TMH.
    Kontogiorgos, Dimosthenis
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Tal, musik och hörsel, TMH.
    Kjellström, Hedvig
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Robotik, perception och lärande, RPL.
    Beskow, Jonas
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Tal, musik och hörsel, TMH.
    Modeling of Human Visual Attention in Multiparty Open-World Dialogues2019Ingår i: ACM TRANSACTIONS ON HUMAN-ROBOT INTERACTION, ISSN 2573-9522, Vol. 8, nr 2, artikel-id UNSP 8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study proposes, develops, and evaluates methods for modeling the eye-gaze direction and head orientation of a person in multiparty open-world dialogues, as a function of low-level communicative signals generated by his/hers interlocutors. These signals include speech activity, eye-gaze direction, and head orientation, all of which can be estimated in real time during the interaction. By utilizing these signals and novel data representations suitable for the task and context, the developed methods can generate plausible candidate gaze targets in real time. The methods are based on Feedforward Neural Networks and Long Short-Term Memory Networks. The proposed methods are developed using several hours of unrestricted interaction data and their performance is compared with a heuristic baseline method. The study offers an extensive evaluation of the proposed methods that investigates the contribution of different predictors to the accurate generation of candidate gaze targets. The results show that the methods can accurately generate candidate gaze targets when the person being modeled is in a listening state. However, when the person being modeled is in a speaking state, the proposed methods yield significantly lower performance.

  • 411.
    Stork, Johannes A.
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Ek, Carl Henrik
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Kragic, Danica
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Learning Predictive State Representations for Planning2015Ingår i: 2015 IEEE/RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS (IROS), IEEE Press, 2015, s. 3427-3434Konferensbidrag (Refereegranskat)
    Abstract [en]

    Predictive State Representations (PSRs) allow modeling of dynamical systems directly in observables and without relying on latent variable representations. A problem that arises from learning PSRs is that it is often hard to attribute semantic meaning to the learned representation. This makes generalization and planning in PSRs challenging. In this paper, we extend PSRs and introduce the notion of PSRs that include prior information (P-PSRs) to learn representations which are suitable for planning and interpretation. By learning a low-dimensional embedding of test features we map belief points of similar semantic to the same region of a subspace. This facilitates better generalization for planning and semantical interpretation of the learned representation. In specific, we show how to overcome the training sample bias and introduce feature selection such that the resulting representation emphasizes observables related to the planning task. We show that our P-PSRs result in qualitatively meaningful representations and present quantitative results that indicate improved suitability for planning.

  • 412.
    Stork, Johannes Andreas
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Representation and Learning for Robotic Grasping, Caging, and Planning2016Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Robots need to grasp, handle, and manipulate objects, navigate their environment, and understand the state of the world around them. Like all artificial intelligence agents, they have to make predictions, formulate goals, reason about actions, and make plans. Expressive, informative, and compact representations of their state, task, or environment are therefore essential, because they allow us to address these problems by computational means. To create suitable representations, we need to consider the agent’s goals, means or resources, external performance requirements, and have to decide what is relevant to the task.

    This thesis investigates the construction, learning, and application of representations in different robotic scenarios. We study representations and algorithms for agents that have the goal to reliably grasp an object, prevent an object from escaping by caging, or learn a model of their interaction with the environment to be able to plan actions and follow the state of the world. Each of the scenarios considers different aspects of representation: Efficient computation and optimization, tractable reasoning, relating different parameterizations, or autonomous learning and execution of behavior under uncertainty.

    For the grasping agent, we introduce an embedding space that allows us to associate contact locations with hand postures and derive a hierarchical representation of object surfaces which together give rise to an efficient fingertip grasp synthesis algorithm. For the caging agent, we only consider objects with holes through their body which allows us to focus on caging configurations that mechanically interlock objects and hands similar to links of a chain. Further, we change from a geometric to a topology- based representation which allows us to construct caging configurations by control-based optimization and sampling-based search. For the learning agent, we consider the environment and robot as a dynamical system and learn predictive state representations that are directly based on observable data. We demonstrate two contrasting methods to influence the resulting model. For an in-hand manipulation task, we consider training sequences as strings of symbols and introduce feature functions that integrate both actions and observations to reduce state ambiguity. For a simulated visual navigation task, we learn a feature embedding with prior information and training labels to enhance model interpretability while at the same time improving planning performance. 

  • 413.
    Stoyanov, Todor
    et al.
    Orebro Univ, Ctr Appl Autonomous Sensor Syst AASS, Fakultetsgatan 1, S-70182 Orebro, Sweden..
    Krug, Robert
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Robotik, perception och lärande, RPL.
    Kiselev, Andrey
    Orebro Univ, Ctr Appl Autonomous Sensor Syst AASS, Fakultetsgatan 1, S-70182 Orebro, Sweden..
    Sun, Da
    Orebro Univ, Ctr Appl Autonomous Sensor Syst AASS, Fakultetsgatan 1, S-70182 Orebro, Sweden..
    Loutfi, Amy
    Orebro Univ, Ctr Appl Autonomous Sensor Syst AASS, Fakultetsgatan 1, S-70182 Orebro, Sweden..
    Assisted Telemanipulation: A Stack-of-Tasks Approach to Remote Manipulator Control2018Ingår i: 2018 IEEE/RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS (IROS) / [ed] Maciejewski, AA Okamura, A Bicchi, A Stachniss, C Song, DZ Lee, DH Chaumette, F Ding, H Li, JS Wen, J Roberts, J Masamune, K Chong, NY Amato, N Tsagwarakis, N Rocco, P Asfour, T Chung, WK Yasuyoshi, Y Sun, Y Maciekeski, T Althoefer, K AndradeCetto, J Chung, WK Demircan, E Dias, J Fraisse, P Gross, R Harada, H Hasegawa, Y Hayashibe, M Kiguchi, K Kim, K Kroeger, T Li, Y Ma, S Mochiyama, H Monje, CA Rekleitis, I Roberts, R Stulp, F Tsai, CHD Zollo, L, IEEE , 2018, s. 6640-6645Konferensbidrag (Refereegranskat)
    Abstract [en]

    This article presents an approach for assisted teleoperation of a robot arm, formulated within a real-time stack-of-tasks (SoT) whole-body motion control framework. The approach leverages the hierarchical nature of the SoT framework to integrate operator commands with assistive tasks, such as joint limit and obstacle avoidance or automatic gripper alignment. Thereby some aspects of the teleoperation problem are delegated to the controller and carried out autonomously. The key contributions of this work are two-fold: the first is a method for unobtrusive integration of autonomy in a telemanipulation system; and the second is a user study evaluation of the proposed system in the context of teleoperated pick-and-place tasks. The proposed approach of assistive control was found to result in higher grasp success rates and shorter trajectories than achieved through manual control, without incurring additional cognitive load to the operator.

  • 414.
    Strand, Rickard
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Hayman, Eric
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Correcting radial distortion by circle fitting2005Ingår i: BMVC 2005 - Proceedings of the British Machine Vision Conference 2005, British Machine Vision Association , 2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    A powerful and popular approach for estimating radial lens distortion parameters is to use the fact that lines which are straight in the scene should be imaged as straight lines under the pinhole camera model. This paper revisits this problem using the division model to parameterise the lens distortion. This turns out to have significant advantages over the more conventional parameterisation, especially for a single parameter model. In particular, we demonstrate that the locus of distorted points from a straight line is a circular arc. This allows distortion estimation to be reformulated as circle-fitting for which many algorithms are available. We compare a number of suboptimal methods offering closed-form solutions with an optimal, iterative technique which minimises a cost function on the actual image plane as opposed to existing techniques which suffer from a bias due to the fact that they optimise a geometric cost function on the undistorted image plane.

  • 415.
    Ståhl, Nils
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Bergström, N.
    Ishikawa, M.
    Exploiting high-speed sequences for background subtraction2016Ingår i: Proceedings - 3rd IAPR Asian Conference on Pattern Recognition, ACPR 2015, Institute of Electrical and Electronics Engineers (IEEE), 2016, s. 106-110Konferensbidrag (Refereegranskat)
    Abstract [en]

    Observing the world in high speed can give rise to systems for e.g., tracking with super-human capabilities or extremely low latency human-computer interaction. However, the demand on computational power grows with the increased framerate, limiting the usefulness of such systems. In this paper we propose a background subtraction method aimed at high-speed video which enables higher level algorithms to focus on the interesting regions in the image. We show through experiments on high-speed video that where using conventional background subtraction methods in high-speed videos fail, the proposed method successfully detects the foreground in the image.

  • 416.
    Susano Pinto, André
    et al.
    Dep. Informatics Engineering, Faculty of Engineering, University of Porto, Porto, Portugal.
    Pronobis, Andrzej
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Paulo Reis, Luis
    Dep. Informatics Engineering, Faculty of Engineering, University of Porto, Porto, Portugal.
    Novelty detection using graphical models for semantic room classification2011Ingår i: 15th Portuguese Conference on Artificial Intelligence, EPIA 2011, 2011, s. 326-339Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents an approach to the problem of novelty detection in the context of semantic room categorization. The ability to assign semantic labels to areas in the environment is crucial for autonomous agents aiming to perform complex human-like tasks and human interaction. However, in order to be robust and naturally learn the semantics from the human user, the agent must be able to identify gaps in its own knowledge. To this end, we propose a method based on graphical models to identify novel input which does not match any of the previously learnt semantic descriptions. The method employs a novelty threshold defined in terms of conditional and unconditional probabilities. The novelty threshold is then optimized using an unconditional probability density model trained from unlabelled data.

  • 417.
    Tegin, Johan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Iliev, Boyko
    Örebro University, Sweden.
    Skoglund, Alexander
    Kragic, Danica
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Wikander, Jan
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Real Life Grasping using an Under-actuated Robot Hand - Simulation and Experiments2009Ingår i: ICAR: 2009 14th International Conference on Advanced Robotics, IEEE , 2009, s. 366-373Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present a system which includes an underactuated anthropomorphic hand and control algorithms for autonomous grasping of everyday objects. The system comprises a control framework for hybrid force/position control in simulation and reality, a grasp simulator, and an under-actuated robot hand equipped with tactile sensors. We start by presenting the robot hand, the simulation environment and the control framework that enable dynamic simulation of an under-actuated robot hand. We continue by presenting simulation results and also discuss and exemplify the use of simulation in relation to autonomous grasping. Finally, we use the very same controller in real world grasping experiments to validate the simulations and to exemplify system capabilities and limitations.

  • 418.
    Teye, Mattias
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Azizpour, Hossein
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Robotik, perception och lärande, RPL.
    Smith, Kevin
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Beräkningsvetenskap och beräkningsteknik (CST). Science for Life Laboratory.
    Bayesian Uncertainty Estimation for Batch Normalized Deep Networks2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    We show that training a deep network using batch normalization is equivalent to approximate inference in Bayesian models. We further demonstrate that this finding allows us to make meaningful estimates of the model uncertainty using conventional architectures, without modifications to the network or the training procedure. Our approach is thoroughly validated by measuring the quality of uncertainty in a series of empirical experiments on different tasks. It outperforms baselines with strong statistical significance, and displays competitive performance with recent Bayesian approaches

  • 419.
    Thippur, Akshaya
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Burbridge, C.
    Kunze, L.
    Alberti, Marina
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Folkesson, John
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Jensfelt, Patric
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Hawes, N.
    A comparison of qualitative and metric spatial relation models for scene understanding2015Ingår i: Proceedings of the National Conference on Artificial Intelligence, AI Access Foundation , 2015, Vol. 2, s. 1632-1640Konferensbidrag (Refereegranskat)
    Abstract [en]

    Object recognition systems can be unreliable when run in isolation depending on only image based features, but their performance can be improved when taking scene context into account. In this paper, we present techniques to model and infer object labels in real scenes based on a variety of spatial relations - geometric features which capture how objects co-occur - and compare their efficacy in the context of augmenting perception based object classification in real-world table-top scenes. We utilise a long-term dataset of office table-tops for qualitatively comparing the performances of these techniques. On this dataset, we show that more intricate techniques, have a superior performance but do not generalise well on small training data. We also show that techniques using coarser information perform crudely but sufficiently well in standalone scenarios and generalise well on small training data. We conclude the paper, expanding on the insights we have gained through these comparisons and comment on a few fundamental topics with respect to long-term autonomous robots.

  • 420.
    Thippur, Akshaya
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Ek, Carl Henrik
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Kjellström, Hedvig
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Inferring hand pose: A comparative study of visual shape features2013Ingår i: 2013 10th IEEE International Conference and Workshops on Automatic Face and Gesture Recognition, FG 2013, IEEE , 2013, s. 6553698-Konferensbidrag (Refereegranskat)
    Abstract [en]

    Hand pose estimation from video is essential for a number of applications such as automatic sign language recognition and robot learning from demonstration. However, hand pose estimation is made difficult by the high degree of articulation of the hand; a realistic hand model is described with at least 35 dimensions, which means that it can assume a wide variety of poses, and there is a very high degree of self occlusion for most poses. Furthermore, different parts of the hand display very similar visual appearance; it is difficult to tell fingers apart in video. These properties of hands put hard requirements on visual features used for hand pose estimation and tracking. In this paper, we evaluate three different state-of-the-art visual shape descriptors, which are commonly used for hand and human body pose estimation. We study the nature of the mappings from the hand pose space to the feature spaces spanned by the visual descriptors, in terms of the smoothness, discriminability, and generativity of the pose-feature mappings, as well as their robustness to noise in terms of these properties. Based on this, we give recommendations on in which types of applications each visual shape descriptor is suitable.

  • 421.
    Thunberg, Johan
    et al.
    Department of Autonomous Systems, Swedish Defence Research Institute (FOI).
    Anisi, David
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Ögren, Petter
    Department of Autonomous Systems, Swedish Defence Research Institute (FOI).
    A comparative study of task assignment and path planning methods for multi-UGV missions2009Ingår i: OPTIMIZATION AND COOPERATIVE CONTROL STRATEGIES / [ed] Hirsch, MJ; Commander, CW; Pardalos, PM; Murphey, R, 2009, s. 167-180Konferensbidrag (Refereegranskat)
    Abstract [en]

    Many important problems involving a group of unmanned ground vehicles (UGVs) are closely related to the multi traviling salesman problem (m-TSP). This paper comprises a comparative study of a number of algorithms proposed in the litterature to solve m-TSPs occuring in robotics. The investigated algoritms include two mixed integer linear programming (MILP) formulations, a market based approach (MA), a Voronoi partition step (VP) combined with the local search used in MA, and a deterministic and a stocastic version of the granular tabu search (GTS). To evaluate the algoritms, an m-TSP is derived from a planar environment with polygonal obstacles and uniformly distributed targets and vehicle positions. The results of the comparison indicate that out of the decentralized approaches, the MA yield good solutions but requires long computation times, while VP is fast but not as good. The two MILP approaches suffer from long computation times, and poor results due to the decomposition of the assignment and path planning steps. Finally, the two GTS algorithms yield good results in short times with inputs from MA as well as the much faster VP. Thus the best performing centralized approach is the GTS in combination with the VP. Funded by the Swedish defence materiel administration (FMV) and the Swedish armed forces through the Technologies for Autonomous and Intelligent Systems (TAIS) project. 297316-LB704859

  • 422.
    Thunberg, Johan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Hu, Xiaoming
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Ögren, Petter
    Aeronautical and Systems Technology, Swedish Defence Research Agency (FOI), Sweden.
    A Boolean Control Network Approach to Pursuit Evasion Problems in Polygonal Environments2011Ingår i: 2011 IEEE International Conference on obotics and Automation (ICRA), 2011, s. 4506-4511Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, the multi pursuer version of the pursuit evasion problem in polygonal environments is addressed. This problem is NP-hard, and therefore we seek good enough, but not optimal solutions. By modeling the problem as a Boolean Control Network, we can efficiently keep track of which regions are cleared, and which are not, while the input nodes of the network are used to represent the motion of the pursuers. The environment is partitioned into a set of convex regions, where each region correspond to a set of nodes in the network. The method is implemented in ANSI C, and efficiently solves complex environments containing multiple loops and requiring so-called recontamination. The provided examples demonstrate the effectiveness of the method in terms of computational time

  • 423.
    Thunberg, Johan
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Ögren, Petter
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    A Mixed Integer Linear Programming approach to Pursuit Evasion Problems with optional Connectivity Constraints2011Ingår i: Autonomous Robots, ISSN 0929-5593, E-ISSN 1573-7527, Vol. 31, nr 4, s. 333-343Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we address the multi pursuer version of the pursuit evasion problem in polygonal environments. By discretizing the problem, and applying a Mixed Integer Linear Programming (MILP) framework, we are able to address problems requiring so-called recontamination and also impose additional constraints, such as connectivity between the pursuers. The proposed MILP formulation is less conservative than solutions based on graph discretizations of the environment, but still somewhat more conservative than the original underlying problem. It is well known that MILPs, as well as multi pursuer pursuit evasion problems, are NP-hard. Therefore we apply an iterative Receding Horizon Control (RHC) scheme where a number of smaller MILPs are solved over shorter planning horizons. The proposed approach is implemented in Matlab/Cplex and illustrated by a number of solved examples.

  • 424.
    Tollmar, Konrad
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Perceptuella interfaces - visions or emergent technolgies?2002Ingår i: Friktion - Om mötet mellan olikheter i IT-forskning, Raster Förlag , 2002Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 425.
    Tollmar, Konrad
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Demirdjian, D.
    Darrell, T.
    Gesture + Play Exploring Full-Body Navigation for Virtual Environments2003Ingår i: Computer Vision and Pattern Recognition Workshop, 2003. CVPRW ’03. Conference on, 2003, Vol. 5Konferensbidrag (Refereegranskat)
    Abstract [en]

    Navigating virtual environments usually requires a wired interface, game console, or keyboard. The advent of perceptual interface techniques allows a new option: the passive and untethered sensing of users’ pose and gesture to allow them maneuver through and manipulate virtual worlds. We describe new algorithms for interacting with 3-D environments using real-time articulated body tracking with standard cameras and personal computers. Our method is based on rigid stereo-motion estimation algorithms and uses a linear technique for enforcing articulation constraints. With our tracking system users can navigate virtual environments using 3-D gesture and body poses. We analyze the space of possible perceptual interface abstractions for full-body navigation, and present a prototype system based on these results. We finally describe an initial evaluation of our prototype system with users guiding avatars through a series of 3-D virtual game worlds.

  • 426.
    Tollmar, Konrad
    et al.
    Department of Design Sciences, Lund University.
    Möller, Ted
    Nilsved, Björn
    A Picture is Worth a Thousand Keywords: Exploring Mobile Image-Based Web Searching2008Ingår i: Advances in Human-Computer Interaction, ISSN 1687-5893, E-ISSN 1687-5907, Vol. 2008Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Images of objects as queries is a new approach to search for information on the web. Image-based information retrieval goes beyond only matching images, as information in other modalities also can be extracted from data collections using image search. We have developed a new system that uses images to search for web-based information. This paper has a particular focus towards exploring user’s experience of general mobile image-based Web searches to find what issues and phenomena it contains. This was achieved in a multi-part study by creating and letting respondents test prototypes of mobile image-based search systems and collecting data using interviews, observations, video-observations, and questionnaires. We observed that searching for information only based on visual similarity and without any assistance is sometimes difficult, especially on mobile devices with limited interaction bandwidth. Most of our subjects preferred a search tool that guides the users through the search result based on contextual information, compared to presenting the search result as a plain ranked list.

  • 427.
    Tollmar, Konrad
    et al.
    Department of Informatics, Lund University.
    Yeh, T.
    Darrell, T.
    IDeixis - Searching the Web with mobile images for location-based information2004Ingår i: MOBILE HUMAN-COMPUTER INTERACTION - MOBILEHCI 2004, PROCEEDINGS, 2004, Vol. 3160, s. 288-299Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we describe an image-based approach to finding location-based information from camera-equipped mobile devices. We introduce a point-by-photograph paradigm, where users can specify a location simply by taking pictures. Our technique uses content-based image retrieval methods to search the web or other databases for matching images and their source pages to find relevant location-based information. In contrast to conventional approaches to location detection, our method can refer to distant locations and does not require any physical infrastructure beyond mobile internet service. We have developed a prototype on a camera phone and conducted user studies to demonstrate the efficacy of our approach.

  • 428. Tourani, S.
    et al.
    Mittal, Sudhanshu
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Nagariya, A.
    Chari, V.
    Krishna, M.
    Rolling shutter and motion blur removal for depth cameras2016Ingår i: Proceedings - IEEE International Conference on Robotics and Automation, IEEE conference proceedings, 2016, s. 5098-5105Konferensbidrag (Refereegranskat)
    Abstract [en]

    Structured light range sensors (SLRS) like the Microsoft Kinect have electronic rolling shutters (ERS). The output of such a sensor while in motion is subject to significant motion blur (MB) and rolling shutter (RS) distortion. Most robotic literature still does not explicitly model this distortion, resulting in inaccurate camera motion estimation. In RGBD cameras, we show via experimentation that the distortion undergone by depth images is different from that of color images and provide a mathematical model for it. We propose an algorithm that rectifies for these RS and MB distortions. To assess the performance of the algorithm we conduct an extensive set of experiments for each step of the pipeline. We assess the performance of our algorithm by comparing the performance of the rectified images on scene-flow and camera pose estimation, and show that with our proposed rectification, the performance improvement is significant.

  • 429. Tsiamis, Anastasios
    et al.
    Tumova, Jana
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Bechlioulis, Charalampos P.
    Karras, George C.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Kyriakopoulos, Kostas J.
    Decentralized Leader-Follower Control under High Level Goals without Explicit Communication2015Ingår i: 2015 IEEE/RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS (IROS), IEEE , 2015, s. 5790-5795Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we study the decentralized control problem of a two-agent system under local goal specifications given as temporal logic formulas. The agents collaboratively carry an object in a leader-follower scheme and lack means to exchange messages on-line, i. e., to communicate explicitly. Specifically, we propose a decentralized control protocol and a leader re-election strategy that secure the accomplishment of both agents' local goal specifications. The challenge herein lies in exploiting exclusively implicit inter- robot communication that is a natural outcome of the physical interaction of the robots with the object. An illustrative experiment is included clarifying and verifying the approach.

  • 430.
    Tumova, Jana
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Marzinotto, Alejandro
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Kragic, Danica
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Maximally Satisfying LTL Action Planning2014Ingår i: 2014 IEEE/RSJ International Conference on Intelligent Robots and Systems, (IROS 2014), IEEE , 2014, s. 1503-1510Konferensbidrag (Refereegranskat)
    Abstract [en]

    We focus on autonomous robot action planning problem from Linear Temporal Logic (LTL) specifications, where the action refers to a "simple" motion or manipulation task, such as "go from A to B" or "grasp a ball". At the high-level planning layer, we propose an algorithm to synthesize a maximally satisfying discrete control strategy while taking into account that the robot's action executions may fail. Furthermore, we interface the high-level plan with the robot's low-level controller through a reactive middle-layer formalism called Behavior Trees (BTs). We demonstrate the proposed framework using a NAO robot capable of walking, ball grasping and ball dropping actions.

  • 431.
    Uhlin, Tomas
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Nordlund, Peter
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Maki, Atsuto
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Eklundh, Jan-Olof
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Towards an Active Visual Observer1995Ingår i: Computer Vision, 1995. Proceedings., Fifth International Conference on, 1995, s. 679-686Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present a binocular active vision system that can attend to and fixate a moving target. Our system has an open and expandable design and it forms the first steps of a long term effort towards developing an active observer using vision to interact with the environment, in particular capable of figure-ground segmentation. We also present partial real-time implementations of this system and show their performance in real-world situations together with motor control. In pursuit we particularly focus on occlusions of other targets, both stationary and moving, and integrate three cues, ego- motion, target motion and target disparity, to obtain an overall robust behavior. An active vision system must be open, expandable, and operate with whatever data are available momen- tarily. It must also be equipped with means and meth- ods to direct and change its attention. This system is therefore equipped with motion detection for changing attention and pursuit for maintaining attention, both of which run concurrently.

  • 432. Uma, K.
    et al.
    Kalyanpur, K.
    Ambarkar, H.
    Saranya, R.
    Kannan, Anand
    KTH.
    Scanned compound images using different compression techniques2017Ingår i: Journal of Advanced Research in Dynamical and Control Systems, ISSN 1943-023X, Vol. 9, nr Special Issue 2, s. 994-1000Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This Paper involves a detailed study of different compression techniques of scanned compound images. A compound image is a different kind of image that contains text, natural image and graphic image. Some of the Image compression techniques which include DCT,JPEG, H.264,MMP AND APM-MMP have been reviewed and presented in this paper. Discrete cosine transform (DCT) is a method which compresses the compound image without any loss of data. To compress image DCT is computed using two dimensional functions (2D).Join Picture Expert Group(JPEG) is mostly used as standard format for compressed images. Due to loss of data the compressed image differs from the original image.H.264 is a video compression standard which is also capable of compressing a compound image.MMP is specifically calculated to encode separately the macro blocks information of text and image. Since complexity is high in these above techniques the proposed technique Adaptive Probability Model-MMP solves the limitations like redundant data removal and enhances the image quality. It also improves the encoding efficiency thus modifying the MMP’s character.

  • 433. Undeman, Carl
    et al.
    Lindeberg, Tony
    KTH, Skolan för datavetenskap och kommunikation (CSC), Beräkningsbiologi, CB.
    Fully Automatic Segmentation of MRI Brain Images using Probabilistic Anisotropic Diffusion and Multi-Scale Watersheds2003Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This article presents a fully automatic method for segmenting the brain from other tissue in a 3-D MR image of the human head. The method is a an extension and combination of previous techniques, and consists of the following processing steps: (i) After an initial intensity normalization, an affine alignment is performed to a standard anatomical space, where the unsegmented image can be compared to a segmented standard brain. (ii) Probabilistic diffusion, guided by probability measures between white matter, grey matter and cerebrospinal fluid, is performed in order to suppress the influence of extra-cerebral tissue. (iii) A multi-scale watershed segmentation step creates a slightly over-segmented image, where the brain contour constitutes a subset of the watershed boundaries.(iv) A segmentation of the over-segmented brain is then selected by using spatial information from the pre-segmented standard brain in combination with additional stages of probabilistic diffusion, morphological operations and thresholding.

    The composed algorithm has been evaluated on 50 T1-weighted MR volumes, by visual inspection and by computing quantitative measures of (i) the similarity between the segmented brain and a manual segmentation of the same brain, and (ii) the ratio of the volumetric difference between automatically and manually segmented brains relative to the volume of the manually segmented brain. The mean value of the similarity index was 0.9961 with standard deviation 0.0034 (worst value 0.9813, best 0.9998). The mean percentage volume error was 0.77 % with standard deviation 0.69 % (maximum percentage error 3.81 %, minimum percentage error 0.05 %).

  • 434. Undeman, Carl
    et al.
    Lindeberg, Tony
    KTH, Skolan för datavetenskap och kommunikation (CSC), Beräkningsbiologi, CB.
    Fully Automatic Segmentation of MRI Brain Images using Probabilistic Anisotropic Diffusion and Multi-Scale Watersheds2003Ingår i: Scale Space'03 Proceedings of the 4th International Conference on Scale space methods in computer vision, Springer Berlin/Heidelberg, 2003, Vol. 2695, s. 641-656Konferensbidrag (Refereegranskat)
    Abstract [en]

    This article presents a fully automatic method for segmenting the brain from other tissue in a 3-D MR image of the human head. The method is a an extension and combination of previous techniques, and consists of the following processing steps: (i) After an initial intensity normalization, an affine alignment is performed to a standard anatomical space, where the unsegmented image can be compared to a segmented standard brain. (ii) Probabilistic diffusion, guided by probability measures between white matter, grey matter and cerebrospinal fluid, is performed in order to suppress the influence of extra-cerebral tissue. (iii) A multi-scale watershed segmentation step creates a slightly over-segmented image, where the brain contour constitutes a subset of the watershed boundaries. (iv) A segmentation of the over-segmented brain is then selected by using spatial information from the pre-segmented standard brain in combination with additional stages of probabilistic diffusion, morphological operations and thresholding. The composed algorithm has been evaluated on 50 T1-weighted MR volumes, by visual inspection and by computing quantitative measures of (i) the similarity between the segmented brain and a manual segmentation of the same brain, and (ii) the ratio of the volumetric difference between automatically and manually segmented brains relative to the volume of the manually segmented brain. The mean value of the similarity index was 0.9961 with standard deviation 0.0034 (worst value 0.9813, best 0.9998). The mean percentage volume error was 0.77 % with standard deviation 0.69 % (maximum percentage error 3.81 %, minimum percentage error 0.05 %).

  • 435.
    Varava, Anastasiia
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Kragic, Danica
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Pokorny, Florian T.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Caging Grasps of Rigid and Partially Deformable 3-D Objects With Double Fork and Neck Features2016Ingår i: IEEE Transactions on robotics, ISSN 1552-3098, E-ISSN 1941-0468, Vol. 32, nr 6, s. 1479-1497Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Caging provides an alternative to point-contact-based rigid grasping, relying on reasoning about the global free configuration space of an object under consideration. While substantial progress has been made toward the analysis, verification, and synthesis of cages of polygonal objects in the plane, the use of caging as a tool for manipulating general complex objects in 3-D remains challenging. In this work, we introduce the problem of caging rigid and partially deformable 3-D objects, which exhibit geometric features we call double forks and necks. Our approach is based on the linking number-a classical topological invariant, allowing us to determine sufficient conditions for caging objects with these features even in the case when the object under consideration is partially deformable under a set of neck or double fork preserving deformations. We present synthesis and verification algorithms and demonstrations of applying these algorithms to cage 3-D meshes.

  • 436. Vasile, C. -I
    et al.
    Tumova, Jana
    KTH, Skolan för datavetenskap och kommunikation (CSC), Robotik, perception och lärande, RPL.
    Karaman, S.
    Belta, C.
    Rus, D.
    Minimum-violation scLTL motion planning for mobility-on-demand2017Ingår i: 2017 IEEE International Conference on Robotics and Automation (ICRA), Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 1481-1488, artikel-id 7989177Konferensbidrag (Refereegranskat)
    Abstract [en]

    This work focuses on integrated routing and motion planning for an autonomous vehicle in a road network. We consider a problem in which customer demands need to be met within desired deadlines, and the rules of the road need to be satisfied. The vehicle might not, however, be able to satisfy these two goals at the same time. We propose a systematic way to compromise between delaying the satisfaction of the given demand and violating the road rules. We utilize scLTL formulas to specify desired behavior and develop a receding horizon approach including a periodically interacting routing algorithm and a RRT<-based motion planner. The proposed solution yields a provably minimum-violation trajectory. An illustrative case study is included.

  • 437.
    Vina, Francisco
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Smith, Christian
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Kragic, Danica
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Karayiannidis, Yiannis
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Adaptive Contact Point Estimation for Autonomous Tool Manipulation2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    Autonomous grasping and manipulation of toolsenables robots to perform a large variety of tasks in unstructuredenvironments such as households. Many commonhousehold tasks involve controlling the motion of the tip of a toolwhile it is in contact with another object. Thus, for these types oftasks the robot requires knowledge of the location of the contactpoint while it is executing the task in order to accomplish themanipulation objective. In this work we propose an integraladaptive control law that uses force/torque measurements toestimate online the location of the contact point between thetool manipulated by the robot and the surface which the tooltouches

  • 438.
    Viña Barrientos, Francisco
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Robotic Manipulation under Uncertainty and Limited Dexterity2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Robotic manipulators today are mostly constrained to perform fixed, repetitive tasks. Engineers design the robot’s workcell specifically tailoredto the task, minimizing all possible uncertainties such as the location of tools and parts that the robot manipulates. However, autonomous robots must be capable of manipulating novel objects with unknown physical properties such as their inertial parameters, friction and shape. In this thesis we address the problem of uncertainty connected to kinematic constraints and friction forces in several robotic manipulation tasks. We design adaptive controllers for opening one degree of freedom mechanisms, such as doors and drawers, under the presence of uncertainty in the kinematic parameters of the system. Furthermore, we formulate adaptive estimators for determining the location of the contact point between a tool grasped by the robot and the environment in manipulation tasks where the robot needs to exert forces with the tool on another object, as in the case of screwing or drilling. We also propose a learning framework based on Gaussian Process regression and dual arm manipulation to estimate the static friction properties of objects. The second problem we address in this thesis is related to the mechanical simplicity of most robotic grippers available in the market. Their lower cost and higher robustness compared to more mechanically advanced hands make them attractive for industrial and research robots. However, the simple mechanical design restrictsthem from performing in-hand manipulation, i.e. repositioning of objects in the robot’s hand, by using the fingers to push, slide and roll the object. Researchers have proposed thus to use extrinsic dexterity instead, i.e. to exploit resources and features of the environment, such as gravity or inertial forces,  that can help the robot to perform regrasps. Given that the robot must then interact with the environment, the problem of uncertainty becomes highly relevant. We propose controllers for performing pivoting, i.e. reorienting the grasped object in the robot’s hand, using gravity and controlling the friction exerted by the fingertips by varying the grasping force.

  • 439.
    Viña Barrientos, Francisco
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Karayiannidis, Yiannis
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Smith, Christian
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Kragic, Danica
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Adaptive Control for Pivoting with Visual and Tactile Feedback2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this work we present an adaptive control approach for pivoting, which is an in-hand manipulation maneuver that consists of rotating a grasped object to a desired orientation relative to the robot’s hand. We perform pivoting by means of gravity, allowing the object to rotate between the fingers of a one degree of freedom gripper and controlling the gripping force to ensure that the object follows a reference trajectory and arrives at the desired angular position. We use a visual pose estimation system to track the pose of the object and force measurements from tactile sensors to control the gripping force. The adaptive controller employs an update law that accommodates for errors in the friction coefficient,which is one of the most common sources of uncertainty in manipulation. Our experiments confirm that the proposed adaptive controller successfully pivots a grasped object in the presence of uncertainty in the object’s friction parameters.

  • 440. Wang, L.
    et al.
    Wang, X.
    Hu, Xiaoming
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Distributed tracking and connectivity maintenance with a varying velocity leader2012Ingår i: 2012 12th International Conference on Control, Automation, Robotics and Vision, ICARCV 2012, IEEE , 2012, s. 1824-1829Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper investigates a distributed tracking problem for multi-agent systems with a varying-velocity leader. The leader modeled by a double integrator can only be perceived by followers located within a sensing distance. The objective is to drive the followers with bounded control law to maintain connectivity, avoid collision and further track the leader, with no need of acceleration measurements. Two cases are considered: the acceleration of the leader is bounded; and the acceleration has a linear form. In the first case, the relative velocities of neighbors are integrated and transmitted as a new variable to account for the uncertain time-varying acceleration. In the second case, two distributed estimators are added for the leader's position and velocity. Simulations are presented to show the effectiveness of the proposed control laws.

  • 441.
    Wang, Wei
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Zhai, Qinglin
    Natl Univ Def Technol, Coll Elect Sci & Engn, Changsha 410073, Hunan, Peoples R China..
    Ban, Yifang
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Samhällsplanering och miljö, Geoinformatik.
    Zhang, Jun
    Natl Univ Def Technol, Coll Elect Sci & Engn, Changsha 410073, Hunan, Peoples R China..
    Wan, Jianwei
    Natl Univ Def Technol, Coll Elect Sci & Engn, Changsha 410073, Hunan, Peoples R China..
    POLSAR IMAGE SEGMENTATION BASED ON HIERARCHICAL REGION MERGING AND SEGMENT REFINEMENT WITH WMRF MODEL2017Ingår i: 2017 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM (IGARSS), IEEE , 2017, s. 4574-4577Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, a superpixel-based segmentation method is proposed for PolSAR images by utilizing hierarchical region merging and segment refinement. The loss of the energy function, which determines the consistency of two adjacent regions from the statistical aspect, is applied to guide the merging procedure. In addition to the edge penalty term, the homogeneity measurement is also employed to prevent merging the regions that are from different land covers or objects. Based on the merged segments, the segment refinement is applied to further improve the segmentation accuracy by iteratively relabeling the edge pixels. It uses a maximum a posterior (MAP) criterion using the statistical distribution of the pixels and the Markov random field (MRF) model. The performance of the proposed method is validated on an experimental PolSAR dataset from the ESAR system.

  • 442.
    Wang, Weixing
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT). Collage of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian, China.
    Liang, Y.
    Rock fracture centerline extraction based on hessian matrix and steger algorithm2015Ingår i: KSII Transactions on Internet and Information Systems, ISSN 1976-7277, Vol. 9, nr 12, s. 5073-5086Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The rock fracture detection by image analysis is significant for fracture measurement and assessment engineering. The paper proposes a novel image segmentation algorithm for the centerline tracing of a rock fracture based on Hessian Matrix at Multi-scales and Steger algorithm. A traditional fracture detection method, which does edge detection first, then makes image binarization, and finally performs noise removal and fracture gap linking, is difficult for images of rough rock surfaces. To overcome the problem, the new algorithm extracts the centerlines directly from a gray level image. It includes three steps: (1) Hessian Matrix and Frangi filter are adopted to enhance the curvilinear structures, then after image binarization, the spurious-fractures and noise are removed by synthesizing the area, circularity and rectangularity; (2) On the binary image, Steger algorithm is used to detect fracture centerline points, then the centerline points or segments are linked according to the gap distance and the angle differences; and (3) Based on the above centerline detection roughly, the centerline points are searched in the original image in a local window along the direction perpendicular to the normal of the centerline, then these points are linked. A number of rock fracture images have been tested, and the testing results show that compared to other traditional algorithms, the proposed algorithm can extract rock fracture centerlines accurately.

  • 443.
    Wang, Yuquan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Liu, Hongyi
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Ji, Wei
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Wang, Wei
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Realtime collaborating with an industrial manipulator using a constraint-based programming approach2018Ingår i: 51st CIRP Conference on Manufacturing Systems, Elsevier, 2018, s. 105-110Konferensbidrag (Refereegranskat)
    Abstract [en]

    Safety is the first and foremost step on our long journey to a future in which robots are moving out of the cage to collaborate with and assist people in various fields from entertainment to manufacturing. Different from the well-defined structured environment, safe robot control in a workspace with moving objects, e.g. a human, requires us to control the robot motion on the fly. In order to computationally efficiently achieve a feasible solution, we propose a constraint-based programming approach to guarantee the safe human-robot interaction. We use an optimization framework to integrate constraints from two-fold: the robot control constraints that are responsible for a generic robotic task and the online formulated safety constraints that are responsible for safe human-robot interaction. In this way, we preserve the task execution ability of a robot while guarantee the safe human-robot interaction. We validate the proposed approach with a Schunk industrial manipulator. The experimental results confirms the fact that the proposed approach has the potential to enable an industrial manipulator to work with a human coworker side-by-side.

  • 444.
    Welle, Michael
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Robotik, perception och lärande, RPL. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Ericson, Ludvig
    KTH, Skolan för datavetenskap och kommunikation (CSC), Robotik, perception och lärande, RPL. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Ambrus, Rares
    KTH, Skolan för datavetenskap och kommunikation (CSC), Robotik, perception och lärande, RPL. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Jensfelt, Patric
    KTH, Skolan för datavetenskap och kommunikation (CSC), Robotik, perception och lärande, RPL. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    On the use of Unmanned Aerial Vehicles for Autonomous Object Modeling2017Ingår i: 2017 European Conference on Mobile Robots, ECMR 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, artikel-id 8098656Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we present an end to end object modeling pipeline for an unmanned aerial vehicle (UAV). We contribute a UAV system which is able to autonomously plan a path, navigate, acquire views of an object in the environment from which a model is built. The UAV does collision checking of the path and navigates only to those areas deemed safe. The data acquired is sent to a registration system which segments out the object of interest and fuses the data. We also show a qualitative comparison of our results with previous work.

  • 445. Wiltschi, Klaus
    et al.
    Pinz, Axel
    Lindeberg, Tony
    KTH, Tidigare Institutioner (före 2005), Numerisk analys och datalogi, NADA.
    Classification of Carbide Distributions using Scale Selection and Directional Distributions1997Ingår i: Proc. 4th International Conference on Image Processing: ICIP'97, 1997, Vol. II, s. 122-125Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents an automatic system for steel quality assessment, by measuring textural properties of carbide distributions. In current steel inspection, specially etched and polished steel specimen surfaces are classified manually under a light microscope, by comparisons with a standard chart. This procedure is basically two-dimensional, reflecting the size of the carbide agglomerations and their directional distribution. To capture these textural properties in terms of image features, we first apply a rich set of image-processing operations, including mathematical morphology, multi-channel Gabor filtering, and the computation of texture measures with automatic scale selection in linear scale-space. Then, a feature selector is applied to a 40-dimensional feature space, and a classification scheme is defined, which on a sample set of more than 400 images has classification performance values comparable to those of human metallographers. Finally, a fully automatic inspection system is designed, which actively selects the most salient carbide structure on the specimen surface for subsequent classification. The feasibility of the overall approach for future use in the production process is demonstrated by a prototype system. It is also shown how the presented classification scheme allows for the definition of a new reference chart in terms of quantitative measures.

  • 446. Wyatt, Jeremy L.
    et al.
    Aydemir, Alper
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS. KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Brenner, Michael
    Hanheide, Marc
    Hawes, Nick
    Jensfelt, Patric
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS. KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Kristan, Matej
    Kruijff, Geert-Jan M.
    Lison, Pierre
    Pronobis, Andrzej
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Sjöö, Kristoffer
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS. KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Vrecko, Alen
    Zender, Hendrik
    Zillich, Michael
    Skocaj, Danijel
    Self-Understanding and Self-Extension: A Systems and Representational Approach2010Ingår i: IEEE T AUTON MENT DE, ISSN 1943-0604, Vol. 2, nr 4, s. 282-303Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There are many different approaches to building a system that can engage in autonomous mental development. In this paper, we present an approach based on what we term self-understanding, by which we mean the explicit representation of and reasoning about what a system does and does not know, and how that knowledge changes under action. We present an architecture and a set of representations used in two robot systems that exhibit a limited degree of autonomous mental development, which we term self-extension. The contributions include: representations of gaps and uncertainty for specific kinds of knowledge, and a goal management and planning system for setting and achieving learning goals.

  • 447. Yang, N.
    et al.
    Wang, W. -X
    KTH.
    Wang, F. -P
    Xue, B. -Y
    Wang, K.
    KTH.
    Road information change detection based on fractional integral and neighborhood FCM2018Ingår i: Chang'an Daxue Xuebao (Ziran Kexue Ban)/Journal of Chang'an University (Natural Science Edition), ISSN 1671-8879, Vol. 38, nr 2, s. 103-111Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to improve the accuracy of road information change detection, a new road information change detection method based on fractional integral and spatial neighborhood fuzzy C-means (FCM) algorithm was presented. Firstly, a new difference image was generated by the gray difference calculation of the dual phase remote sensing images after registration and geometric correction. Then, a smaller fractional integral order was used to construct the denoising image mask with eight directions on the upper and lower, left and right, and four diagonals, and the fractional integral calculation were applied to the difference images, which improved the image signal-to-noise ratio (SNR) while preserving the edge and texture details of the image. Finally, the FCM clustering method combined with neighborhood spatial information was used to calculate the difference image after denoising. The highest and lowest points of the difference image gray values were selected as the center point of cluster initialization. The Euclidean Metric of the neighborhood were used to depict different weight values, so as to characterize the influence degree of domain pixels on central pixels and eliminate invalid isolated points. Detecting probability, false alarm rate and missed alarm rate of the algorithm were evaluated by the experiment. The results show that FCM road information change detection method based on fractional integral and neighborhood spatial information can effectively extract road change information. When the integral fractional order is 0.2, the FCM smoothing parameter is 2.5, the detection probability is higher than the comparison algorithm by 18% to 46%, the false alarm rate is lower than the comparison algorithm by 15% to 38%, and the missed alarm rate is lower than the comparison algorithm by 3% to 7%. The present algorithm can achieve better results in suppressing noise information and enhancing texture details. Especially, when the center pixel is noise, due to the introduction of neighborhood information, and it is affected by the neighborhood normal pixels. The proposed method could avoid misclassification by adjusting the membership automatically, it can effectively suppress the influence of neighborhood noise points on the normal pixel classification, and reduce the false alarm rate. 2 tabs, 4 figs, 28 refs. 

  • 448. Yeh, T.
    et al.
    Tollmar, Konrad
    MIT CSAIL, Cambridge.
    Darrell, T.
    Searching the Web with mobile images for location recognition2004Ingår i: PROCEEDINGS OF THE 2004 IEEE COMPUTER SOCIETY CONFERENCE ON COMPUTER VISION AND PATTERN RECOGNITION, VOL 2, 2004, Vol. 2, s. 76-81Konferensbidrag (Refereegranskat)
    Abstract [en]

    We describe an approach to recognizing location from mobile devices using image-based Web search. We demonstrate the usefulness of common image search metrics applied on images captured with a camera-equipped mobile device to find matching images on the World Wide Web or other general-purpose databases. Searching the entire Web can be computationally overwhelming, so we devise a hybrid image-and-keyword searching technique. First, image-search is performed over images and links to their source Web pages in a database that indexes only a small fraction of the Web. Then, relevant keywords on these Web pages are automatically identified and submitted to an existing text-based search engine (e.g. Google) that indexes a much larger portion of the Web. Finally, the resulting image set is filtered to retain images close to the original query. It is thus possible to efficiently search hundreds of millions of images that are not only textually related but also visually relevant. We demonstrate our approach on an application allowing users to browse Web pages matching the image of a nearby location.

  • 449. Yeh, Tom
    et al.
    Grauman, Kristen
    Tollmar, Konrad
    Darrell, Trevor
    A picture is worth a thousand keywords: image-based object search on a mobile platform2005Ingår i: CHI ’05 extended abstracts on Human factors in computing systems, 2005, s. 2025-2028Konferensbidrag (Refereegranskat)
    Abstract [en]

    Finding information based on an object’s visual appearance is useful when specific keywords for the object are not known. We have developed a mobile image-based search system that takes images of objects as queries and finds relevant web pages by matching them to similar images on the web. Image-based search works well when matching full scenes, such as images of buildings or landmarks, and for matching objects when the boundary of the object in the image is available. We demonstrate the effectiveness of a simple interactive paradigm for obtaining a segmented object boundary, and show how a shape-based image matching algorithm can use the object outline to find similar images on the web.

  • 450. Yeh, Tom
    et al.
    Tollmar, Konrad
    Darrell, Trevor
    IDeixis: image-based Deixis for finding location-based information2004Ingår i: CHI ’04 extended abstracts on Human factors in computing systems, 2004, s. 781-782Konferensbidrag (Refereegranskat)
    Abstract [en]

    We demonstrate an image-based approach to specifying location and finding location-based information from camera-equipped mobile devices. We introduce a point-by-photograph paradigm, where users can specify a location simply by taking pictures. Our technique uses content-based image retrieval methods to search the web or other databases for matching images and their source pages to find relevant location-based information. In contrast to conventional approaches to location detection, our method can refer to distant locations and does not require any physical infrastructure beyond mobile internet service. We have developed a prototype on a camera phone and conducted user studies to demonstrate the efficacy of our approach compared to other alternatives.

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