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  • 46451.
    Öfjäll, Kristoffer
    Linköpings universitet, Institutionen för systemteknik, Bildbehandling. Linköpings universitet, Tekniska högskolan.
    LEAP, A Platform for Evaluation of Control Algorithms2010Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Most people are familiar with the BRIO labyrinth game and the challenge of guiding the ball through the maze. The goal of this project was to use this game to create a platform for evaluation of control algorithms. The platform was used to evaluate a few different controlling algorithms, both traditional automatic control algorithms as well as algorithms based on online incremental learning.

    The game was fitted with servo actuators for tilting the maze. A camera together with computer vision algorithms were used to estimate the state of the game. The evaluated controlling algorithm had the task of calculating a proper control signal, given the estimated state of the game.

    The evaluated learning systems used traditional control algorithms to provide initial training data. After initial training, the systems learned from their own actions and after a while they outperformed the controller used to provide initial training.

  • 46452.
    Öfjäll, Kristoffer
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska högskolan.
    Online Learning for Robot Vision2014Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In tele-operated robotics applications, the primary information channel from the robot to its human operator is a video stream. For autonomous robotic systems however, a much larger selection of sensors is employed, although the most relevant information for the operation of the robot is still available in a single video stream. The issue lies in autonomously interpreting the visual data and extracting the relevant information, something humans and animals perform strikingly well. On the other hand, humans have great diculty expressing what they are actually looking for on a low level, suitable for direct implementation on a machine. For instance objects tend to be already detected when the visual information reaches the conscious mind, with almost no clues remaining regarding how the object was identied in the rst place. This became apparent already when Seymour Papert gathered a group of summer workers to solve the computer vision problem 48 years ago [35].

    Articial learning systems can overcome this gap between the level of human visual reasoning and low-level machine vision processing. If a human teacher can provide examples of what to be extracted and if the learning system is able to extract the gist of these examples, the gap is bridged. There are however some special demands on a learning system for it to perform successfully in a visual context. First, low level visual input is often of high dimensionality such that the learning system needs to handle large inputs. Second, visual information is often ambiguous such that the learning system needs to be able to handle multi modal outputs, i.e. multiple hypotheses. Typically, the relations to be learned  are non-linear and there is an advantage if data can be processed at video rate, even after presenting many examples to the learning system. In general, there seems to be a lack of such methods.

    This thesis presents systems for learning perception-action mappings for robotic systems with visual input. A range of problems are discussed, such as vision based autonomous driving, inverse kinematics of a robotic manipulator and controlling a dynamical system. Operational systems demonstrating solutions to these problems are presented. Two dierent approaches for providing training data are explored, learning from demonstration (supervised learning) and explorative learning (self-supervised learning). A novel learning method fullling the stated demands is presented. The method, qHebb, is based on associative Hebbian learning on data in channel representation. Properties of the method are demonstrated on a vision-based autonomously driving vehicle, where the system learns to directly map low-level image features to control signals. After an initial training period, the system seamlessly continues autonomously. In a quantitative evaluation, the proposed online learning method performed comparably with state of the art batch learning methods.

  • 46453.
    Öfjäll, Kristoffer
    et al.
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska högskolan.
    Felsberg, Michael
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Biologically Inspired Online Learning of Visual Autonomous Driving2014Ingår i: Proceedings British Machine Vision Conference 2014 / [ed] Michel Valstar; Andrew French; Tony Pridmore, BMVA Press , 2014, 137-156 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    While autonomously driving systems accumulate more and more sensors as well as highly specialized visual features and engineered solutions, the human visual system provides evidence that visual input and simple low level image features are sufficient for successful driving. In this paper we propose extensions (non-linear update and coherence weighting) to one of the simplest biologically inspired learning schemes (Hebbian learning). We show that this is sufficient for online learning of visual autonomous driving, where the system learns to directly map low level image features to control signals. After the initial training period, the system seamlessly continues autonomously. This extended Hebbian algorithm, qHebb, has constant bounds on time and memory complexity for training and evaluation, independent of the number of training samples presented to the system. Further, the proposed algorithm compares favorably to state of the art engineered batch learning algorithms.

  • 46454.
    Öfjäll, Kristoffer
    et al.
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska högskolan.
    Felsberg, Michael
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Combining Vision, Machine Learning and Automatic Control to Play the Labyrinth Game2012Ingår i: Proceedings of SSBA, Swedish Symposium on Image Analysis, 2012, 2012Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The labyrinth game is a simple yet challenging platform, not only for humans but also for control algorithms and systems. The game is easy to understand but still very hard to master. From a system point of view, the ball behavior is in general easy to model but close to the obstacles there are severe non-linearities. Additionally, the far from flat surface on which the ball rolls provides for changing dynamics depending on the ball position.

    The general dynamics of the system can easily be handled by traditional automatic control methods. Taking the obstacles and uneven surface into account would require very detailed models of the system. A simple deterministic control algorithm is combined with a learning control method. The simple control method provides initial training data. As thelearning method is trained, the system can learn from the results of its own actions and the performance improves well beyond the performance of the initial controller.

    A vision system and image analysis is used to estimate the ball position while a combination of a PID controller and a learning controller based on LWPR is used to learn to steer the ball through the maze.

  • 46455.
    Öfjäll, Kristoffer
    et al.
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska högskolan.
    Felsberg, Michael
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Integrating Learning and Optimization for Active Vision Inverse Kinematics2013Ingår i: Proceedings of SSBA, Swedish Symposium on Image Analysis, 2013, 2013Konferensbidrag (Övrigt vetenskapligt)
  • 46456.
    Öfjäll, Kristoffer
    et al.
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska högskolan.
    Felsberg, Michael
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Online Learning and Mode Switching for Autonomous Driving from Demonstration2014Ingår i: Proceedings of SSBA, Swedish Symposium on Image Analysis, 2014, 2014Konferensbidrag (Övrigt vetenskapligt)
  • 46457.
    Öfjäll, Kristoffer
    et al.
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska fakulteten.
    Felsberg, Michael
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska fakulteten.
    Online learning of autonomous driving using channel representations of multi-modal joint distributions2015Ingår i: Proceedings of SSBA, Swedish Symposium on Image Analysis, 2015, Swedish Society for automated image analysis , 2015Konferensbidrag (Övrigt vetenskapligt)
  • 46458.
    Öfjäll, Kristoffer
    et al.
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska högskolan.
    Felsberg, Michael
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska högskolan.
    Online Learning of Vision-Based Robot Control during Autonomous Operation2015Ingår i: New Development in Robot Vision / [ed] Yu Sun, Aman Behal and Chi-Kit Ronald Chung, Springer Berlin/Heidelberg, 2015, 137-156 s.Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Online learning of vision-based robot control requires appropriate activation strategies during operation. In this chapter we present such a learning approach with applications to two areas of vision-based robot control. In the first setting, selfevaluation is possible for the learning system and the system autonomously switches to learning mode for producing the necessary training data by exploration. The other application is in a setting where external information is required for determining the correctness of an action. Therefore, an operator provides training data when required, leading to an automatic mode switch to online learning from demonstration. In experiments for the first setting, the system is able to autonomously learn the inverse kinematics of a robotic arm. We propose improvements producing more informative training data compared to random exploration. This reduces training time and limits learning to regions where the learnt mapping is used. The learnt region is extended autonomously on demand. In experiments for the second setting, we present an autonomous driving system learning a mapping from visual input to control signals, which is trained by manually steering the robot. After the initial training period, the system seamlessly continues autonomously. Manual control can be taken back at any time for providing additional training.

    Publikationen är tillgänglig i fulltext från 2018-01-01 00:00
  • 46459.
    Öfjäll, Kristoffer
    et al.
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska högskolan.
    Felsberg, Michael
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Weighted Update and Comparison for Channel-Based Distribution Field Tracking2015Ingår i: COMPUTER VISION - ECCV 2014 WORKSHOPS, PT II, Springer, 2015, Vol. 8926, 218-231 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    There are three major issues for visual object trackers: modelrepresentation, search and model update. In this paper we address thelast two issues for a specic model representation, grid based distributionmodels by means of channel-based distribution elds. Particularly weaddress the comparison part of searching. Previous work in the areahas used standard methods for comparison and update, not exploitingall the possibilities of the representation. In this work we propose twocomparison schemes and one update scheme adapted to the distributionmodel. The proposed schemes signicantly improve the accuracy androbustness on the Visual Object Tracking (VOT) 2014 Challenge dataset.

  • 46460.
    Öfjäll, Kristoffer
    et al.
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska fakulteten.
    Felsberg, Michael
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Robinson, Andreas
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska fakulteten.
    Visual Autonomous Road Following by Symbiotic Online Learning2016Ingår i: Intelligent Vehicles Symposium (IV), 2016 IEEE, 2016, 136-143 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Recent years have shown great progress in driving assistance systems, approaching autonomous driving step by step. Many approaches rely on lane markers however, which limits the system to larger paved roads and poses problems during winter. In this work we explore an alternative approach to visual road following based on online learning. The system learns the current visual appearance of the road while the vehicle is operated by a human. When driving onto a new type of road, the human driver will drive for a minute while the system learns. After training, the human driver can let go of the controls. The present work proposes a novel approach to online perception-action learning for the specific problem of road following, which makes interchangeably use of supervised learning (by demonstration), instantaneous reinforcement learning, and unsupervised learning (self-reinforcement learning). The proposed method, symbiotic online learning of associations and regression (SOLAR), extends previous work on qHebb-learning in three ways: priors are introduced to enforce mode selection and to drive learning towards particular goals, the qHebb-learning methods is complemented with a reinforcement variant, and a self-assessment method based on predictive coding is proposed. The SOLAR algorithm is compared to qHebb-learning and deep learning for the task of road following, implemented on a model RC-car. The system demonstrates an ability to learn to follow paved and gravel roads outdoors. Further, the system is evaluated in a controlled indoor environment which provides quantifiable results. The experiments show that the SOLAR algorithm results in autonomous capabilities that go beyond those of existing methods with respect to speed, accuracy, and functionality. 

  • 46461.
    Öfverholm, Rebecka
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Towards Functional Relation Learning with a Physical Robot.2012Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Målet med detta projekt är att undersöka möjligheten för en robot att själv lära sig en modell för funktionella spatiala relationer genom att interagera med sin miljö. Jag testar detta genom att låta en robot lära sig de två relationerna "positionskontroll" och "stöd", som båda är viktiga delar av den spatiella prepositionen "på". Detta görs genom en fysiksimulering där en robotarm får interagera med olika sorters föremål i en virtuell scen, med hjälp av ramverket OpenRAVE. Roboten manipulerar föremål i scenen för att testa varje relation, och de data som genereras används i inlärning med Sparse Bayesian models för att träna en klassifierare. Resultaten visar att inlärning av funktionella relationer är möjlig, trots begränsningar både i möjligheten att hitta grepp och i fysiksimuleringens kvalitet.

  • 46462.
    Öfverstedt, Johan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för beräkningsvetenskap. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Tillämpad beräkningsvetenskap.
    Normann, Per
    Deterministic parallel graph coloring with repartitioning by auxiliary graph coloring2015Rapport (Övrigt vetenskapligt)
  • 46463.
    Ögren, Mikael
    et al.
    Linköpings universitet, Institutionen för datavetenskap.
    Fahlvik, Johanna
    Linköpings universitet, Institutionen för datavetenskap.
    Garplind, Joel
    Linköpings universitet, Institutionen för datavetenskap.
    Karlsson, Emeli
    Linköpings universitet, Institutionen för datavetenskap.
    Löfberg, Fredrik
    Linköpings universitet, Institutionen för datavetenskap.
    Scheid, Adam
    Linköpings universitet, Institutionen för datavetenskap.
    Tegnebord, David
    Linköpings universitet, Institutionen för datavetenskap.
    Trygg, Alexander
    Linköpings universitet, Institutionen för datavetenskap.
    Wåström, Hampus
    Linköpings universitet, Institutionen för datavetenskap.
    Utveckling av en webbutik för köp och sälj av begagnade kläder2015Självständigt arbete på grundnivå (kandidatexamen), 12 poäng / 18 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Rapporten beskriver det tekniska och marknadsmässiga framtagandet av en plattform för handelmed begagnade kläder på internet. Webbapplikationen har namnet Trojo och den främstamålgruppen är miljömedvetna personer mellan 18 och 29 år. Rapportens fokus kommer att liggapå tekniska samt marknadsmässiga aspekter samt relationen mellan dessa. Exempelvis diskuterarrapporten teori som visar på att förbättrade laddningstider generellt sätt ökar försäljningen för ehandlare,och därför behandlar även rapporten hur Trojo arbetat rent tekniskt för att optimeraladdningstiderna. Vikten av att hemsidan klarar av att ta emot trafik från olika enheter kommerockså att behandlas samt hur projektgruppen tekniskt gått tillväga för att göra hemsidanresponsiv. Vilka användarberättelser som ligger bakom det slutgiltiga resultatet, prioriteringenmellan dem samt hur implementationen av dem behandlas också.

    Rapporten mynnar ut i ett resultat som besvarar hur en webbaserad e-butik för begagnade kläderkan realiseras så att den attraherar målgruppen unga och miljömedvetna personer samt går medvinst efter tre år. Hur rapporten kan ses i ett vidare sammanhang diskuteras också och exempelvisinkluderas resonemang kring Trojos potential att påverka miljön positivt. Avslutningsvisbehandlas även hur Trojo skulle kunna fortsätta utvecklingen för att ytterligare optimeramöjligheterna att attrahera den betraktade målgruppen.

  • 46464.
    Ögren, Mikael
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Wikblad, Ludwig
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    En testprocess för webbutvecklingsprojekt med små team2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Att hitta ett lämpligt tillvägagångssätt för att utföra testning i små utvecklingsteam är en utmaning. Många små företag upplever traditionella testprocesser och testförbättringsprocesser som alltför resurskrävande. Minimal Test Practice Framework (MTPF) är ett ramverk för testning vars syfte är att tillhandahålla ett minimalistiskt tillvägagångssätt för testförbättring. Målet med denna studie var att undersöka hur MTPF kan implementeras och anpassas till ett litet utvecklingsteam utan att den medför en för stor tidsinvestering. Studien utfördes på avdelningen Webb \& Mobilt i företaget Exsitec där team om 2-6 personer utvecklar webbapplikationer till företagskunder. I nära samarbete med utvecklarna på avdelningen togs en testprocess fram med målet att den skulle anpassas till verksamheten i så stor utsträckning som möjligt. Studien genomfördes som aktionsforskning i tre faser utefter Cooperative Method Development i ett projekt med två utvecklare. Under studiens första fas intervjuades alla utvecklare på avdelningen för att skapa en grundförståelse för verksamheten. Under den andra fasen togs ett antal förbättringsförslag fram tillsammans med utvecklarna. Under den tredje fasen infördes och utvärderades dessa förbättringar. Genom att fokusera på enhetstestning av central affärslogik i applikationen uppnåddes en testprocess som gav utvecklarna ett ökat förtroende för kodens kvalitet utan att upplevas som för resursintensiv.

  • 46465.
    Ögren, Petter
    Swedish Defence Research Agency (FOI).
    Improved predictability of reactive robot control using Control Lyapunov Functions2008Ingår i: 2008 IEEE/RSJ INTERNATIONAL CONFERENCE ON ROBOTS AND INTELLIGENT SYSTEMS, VOLS 1-3, CONFERENCE PROCEEDINGS, 2008, 1274-1279 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Model based robot control approaches are often designed to allow the verification of certain system properties such as safety or goal convergence. However, designing such controllers is often very time consuming, and most of the time it is not possible to add additional control objectives without jeopardizing the previously proved system properties.

  • 46466.
    Ögren, Petter
    Swedish Defence Research Agency (FOI).
    Split and Join of Vehicle Formations doing Obstacle Avoidance2004Ingår i: 2004 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION, VOLS 1- 5, PROCEEDINGS, 2004, 1951-1955 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we study a scenario where a set of vehicles having different origins and/or destinations move in a common region. The goal is to have the vehicles join and leave formations in a completely decentralized manner. When a vehicle traveling along its own path finds itself moving close to another vehicle it automatically switches into follower mode. The vehicle stays in follower mode as long as the path of the other vehicle is beneficial to it. If, at some point, the leader is not moving towards the destination of the follower, the follower leaves the leader and head of on its own. We address this problem for a group of dynamic unicycle robots. Incorporating the split and join capability into a Receding Horizon Control approach to obstacle avoidance we are able to show safety as well as convergence of all vehicles to their destinations under general nonconvex obstacle assumptions. We illustrate the method with a simulation example

  • 46467.
    Ögren, Petter
    et al.
    Swedish Defence Research Agency (FOI).
    Backlund, Adam
    Swedish Defence Research Agency (FOI).
    Harryson, Tobias
    Swedish Air Force, Air Combat School .
    Kristensson, Lars
    Swedish Defence Research Agency (FOI).
    Stensson, Patrik
    Swedish Air Force, Air Combat School.
    Autonomous UCAV Strike Missions using Behavior Control Lyapunov Functions2006Konferensbidrag (Refereegranskat)
    Abstract [en]

    An autonomous Unmanned Combat Aerial Vehicle (UCAV) carrying out a surveillance or strike mission must be able to handle situations where the different mission objectives are in conflict and a tradeoff must be made, e.g. when the time of arrival is in conflict with the prescribed safety distance to an enemy surface to air missile (SAM) site. This paper describes a framework called Behavior Control Lyapunov Functions (BCLF), to handle such tradeoffs. The framework combines the natural idea of different control behaviors for different mission objectives, suggested in the Behavior Based robotics approach, with the mathematical transparency of Control Lyapunov Functions (CLF) from control theory. First, each behavior is represented by a scalar function with certain CLF-like properties, describing to what extent that mission objective is satisfied. The operator then edits a priority table reflecting the order of importance between different objectives, as well as different levels of satisfaction. Based on the table and the current levels of satisfaction the algorithm decides which objectives should be focused on right now, and which should currently be ignored. Finally, the current high priority objectives are transformed into recommended subsets of the available control choices, and passed to the controller. The paper is concluded with simulation examples illustrating the approach.

  • 46468.
    Ögren, Petter
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Egerstedt, M
    Hu, X
    A control Lyapunov function approach to multi-agent coordination2002Ingår i: IEEE transactions on robotics and automation, ISSN 1042-296X, Vol. 18, nr 5, 847-851 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, the multiagent coordination problem is studied. This problem is addressed for a class of robots for which control Lyapunov functions can be found. The main result is a suite of theorems about formation maintenance, task completion time, and formation velocity. It is also shown how to moderate the requirement that, for each individual robot, there exists a control Lyapunov function. An example is provided that illustrates the soundness of the method

  • 46469.
    Ögren, Petter
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Egerstedt, M
    Hu, X
    A Control Lyapunov Function Approach to Multi-Agent Coordination2001Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, the multiagent coordination problem is studied. This problem is addressed for a class of robots for which control Lyapunov functions can be found. The main result is a suite of theorems about formation maintenance, task completion time, and formation velocity. It is also shown how to moderate the requirement that, for each individual robot, there exists a control Lyapunov function. An example is provided that illustrates the soundness of the method

  • 46470.
    Ögren, Petter
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Egerstedt, M
    Hu, X
    Reactive mobile manipulation using dynamic trajectory tracking2000Konferensbidrag (Refereegranskat)
    Abstract [en]

    A solution to the trajectory tracking problem for mobile manipulators is proposed, that allows for the base to be influenced by a reactive, obstacle avoidance behavior. Given a trajectory for the gripper to follow, a tracking algorithm for the manipulator is designed, and at the same time the base motions are generated in such a way that the base is coordinated with the gripper. Furthermore, it is shown that the method allows arbitrary upper and lower bounds on the gripper-base distance to be set and this can be achieved without introducing deadlocks into the system. The solution also ensures that the control effort, spent on slow base motions, is kept small

  • 46471.
    Ögren, Petter
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Fiorelli, E
    Leonard, N.E.
    Formations with a Mission: Stable Coordination of Vehicle Group Maneuvers2002Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we present a stable coordination strategy for vehicle formation missions that involve group translation, rotation, expansion and contraction. The underlying coordination framework uses artificial potentials and virtual leaders. Symmetry in the framework is exploited to partially decouple the mission control problem into a formation management subproblem and a maneuver management subproblem. The designed dynamics of the virtual leaders play a key role in both subproblems: the direction of motion of the virtual leaders is designed to satisfy the mission while the speed of the virtual leaders is designed to ensure stability and convergence properties of the formation. The latter is guaranteed by regulating the virtual leader speed according to a feedback measurement of an appropriate formation error function. The coordination strategy is illustrated in the context of adaptive gradient climbing missions.

  • 46472.
    Ögren, Petter
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Leonard, N
    Obstacle Avoidance in Formation,2003Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, we present an approach to obstacle avoidance for a group of unmanned vehicles moving in formation. The goal of the group is to move through a partially unknown environment with obstacles and reach a destination while maintaining the formation. We address this problem for a class of dynamic unicycle robots. Using Input-to-State Stability we combine a general class of formation-keeping control schemes with a new dynamic window approach to obstacle avoidance in order to guarantee safety and stability of the formation as well as convergence to the goal position. An important part of the proposed approach can be seen as a formation extension of the configuration space obstacle concept. We illustrate the method with a challenging example.

  • 46473.
    Ögren, Petter
    et al.
    Mech. & Aerosp. Eng. Dept., Princeton Univ., NJ, USA.
    Leonard, Naomi Ehrich
    Mech. & Aerosp. Eng. Dept., Princeton Univ., NJ, USA.
    A Convergent Dynamic Window Approach to Obstacle Avoidance2005Ingår i: IEEE Transactions on robotics, ISSN 1552-3098, Vol. 21, nr 2, 188-195 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The dynamic window approach (DWA) is a well-known navigation scheme developed by Fox et al. and extended by Brock and Khatib. It is safe by construction, and has been shown to perform very efficiently in experimental setups. However, one can construct examples where the proposed scheme fails to attain the goal configuration. What has been lacking is a theoretical treatment of the algorithm's convergence properties. Here we present such a treatment by merging the ideas of the DWA with the convergent, but less performance-oriented, scheme suggested by Rimon and Koditschek. Viewing the DWA as a model predictive control (MPC) method and using the control Lyapunov function (CLF) framework of Rimon and Koditschek, we draw inspiration from an MPC/CLF framework put forth by Primbs to propose a version of the DWA that is tractable and convergent.

  • 46474.
    Ögren, Petter
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Leonard, N.E.
    A Probably Convergent Dynamic Window Approach to Obstaclen Avoidance2002Konferensbidrag (Refereegranskat)
    Abstract [en]

    The dynamic window approach is a well known navigation scheme developed in Fox et al. (1997) and extended in Brock and Khatib (1999). It is safe by construction and has been shown to perform very e#ciently in experimental setups. However, one can construct examples where the proposed scheme fails to attain the goal configuration. What has been lacking is a theoretical treatment of the algorithm's convergence properties. Here we present such a treatment.

  • 46475.
    Ögren, Petter
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Leonard, N.E.
    A tractable convergent dynamic window approach to obstacle avoidance2002Konferensbidrag (Refereegranskat)
    Abstract [en]

    The dynamic window approach is a well known navigation scheme developed by Fox et. al. [1] and extended by Brock and Khatib [2]. It is safe by construction and has been shown to perform very efficiently in experimental setups. However, one can construct examples where the proposed scheme fails to attain the goal configuration. What has been lacking is a theoretical treatment of the algorithm's convergence properties. A first step towards such a treatment was presented in [4]. Here we continue that work with a computationally tractable algorithm resulting from a careful discretization of the optimal control problem of the previous paper and a way to construct a continuous Navigation Function. Inspired by the similarities between the Dynamic Window Approach and the Control Lyapunov Function and Receding Horizon Control synthesis put forth by Primbs et. al. [3] we propose a version of the Dynamic Window Approach that is tractable and provably convergent.

  • 46476.
    Ögren, Petter
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Martin, C.F.
    Optimal Vaccination Strategies for the Control of Epidemics in Highly Mobile Populations2000Konferensbidrag (Refereegranskat)
    Abstract [en]

    Our goal is to calculate optimal vaccination patterns for a rapidly spreading disease in an urbanized highly mobile population. The goal being to determine if vaccination can effect a disease for which there is low immunity in the population. Different types of structured SIR models are investigated. We construct a model appropriate for a traveling urbanized population and introduce a control in terms of a vaccination program. Linear constraints, a quadratic cost on the control and a linear cost on the number of infected are imposed. In this setting we calculate optimal vaccination patterns using the maximum principle of Pontryagin

  • 46477.
    Ögren, Petter
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Martin, C.F
    Vaccination Strategies for Epidemics in Highly Mobile Populations2002Ingår i: Applied Mathematics and Computation, ISSN 0096-3003, E-ISSN 1873-5649, Vol. 127, nr 2-3, 261-276 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Our goal is to calculate optimal vaccination patterns for a rapidly spreading disease in an urbanized highly mobile population. The goal being to determine if vaccination can effect a disease for which there is low immunity in the population. Different types of structured SIR models are investigated. We construct a model appropriate for a traveling urbanized population and introduce a control in terms of a vaccination program. Linear constraints, a quadratic cost on the control and a linear cost on the number of infected are imposed. In this setting we calculate optimal vaccination patterns using the maximum principle of Pontryagin. The numerics are performed using Matlab.

  • 46478.
    Ögren, Petter
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Petersson, L
    Egerstedt, M
    Hu, X
    Reactive mobile manipulation using dynamic trajectory tracking: design and implementation2000Konferensbidrag (Refereegranskat)
    Abstract [en]

    A solution to the trajectory tracking problem for mobile manipulators is proposed and implemented on a real robotic system. Given a trajectory for the gripper to follow, a tracking algorithm for the manipulator is designed, and at the same time the base motions are generated in such a way that the base is coordinated with the gripper while reactively avoiding obstacles. Furthermore, it is shown that the method allows arbitrary upper and lower bounds on the gripper-base distance to be set, and this can be achieved without introducing deadlocks into the system

  • 46479.
    Ögren, Petter
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Robinson, John W.C.
    Swedish Defence Research Agency (FOI), Department of Aeronautics .
    A Model Based Approach to Modular Multi-Objective Robot Control2011Ingår i: Journal of Intelligent and Robotic Systems, ISSN 0921-0296, E-ISSN 1573-0409, Vol. 63, nr 2, 257-282 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two broad classes of robot controllers are the modular, and the model based approaches. The modular approaches include the Reactive or Behavior Based designs. They do not rely on mathematical system models, but are easy to design, modify and extend. In the model based approaches, a model is used to design a single controller with verifiable system properties. The resulting designs are however often hard to extend, without jeopardizing the previously proven properties. This paper describes an attempt to narrow the gap between the flexibility of the modular approaches, and the predictability of the model based approaches, by proposing a modular design that does the combination, or arbitration, of the different modules in a model based way. By taking the (model based) time derivatives of scalar, Lyapunov-like, objective functions into account, the arbitration module can keep track of the time evolution of the objectives. This enables it to handle objective tradeoffs in a predictable way by finding controls that preserve an important objective that is currently met, while striving to satisfy another, less important one that is not yet achieved. To illustrate the approach a UAV control problem from the literature is solved, resulting in comparable, or better, performance.

  • 46480.
    Ögren, Petter
    et al.
    Swedish Defence Research Agency (FOI), Department of Aeronautics and Systems Technology,.
    Robinson, John W.C.
    Swedish Defence Research Agency (FOI), Department of Aeronautics .
    Receding Horizon Control of UAVs using Gradual Dense-Sparse Discretizations2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we propose a way of increasing the eciency of some direct Receding Horizon Control (RHC) schemes. The basic idea is to adapt the allocation of compu- tational resources to how the iterative plans are used. By using Gradual Dense-Sparse discretizations (GDS), we make sure that the plans are detailed where they need to be, i.e., in the very near future, and less detailed further ahead. The gradual transition in discretization density re ects increased uncertainty and reduced need for detail near the end of the planning horizon. The proposed extension is natural, since the standard RHC approach already contains a computational asymmetry in terms of the coarse cost-to-go computations and the more detailed short horizon plans. Using GDS discretizations, we bring this asymmetry one step further, and let the short horizon plans themselves be detailed in the near term and more coarse in the long term. The rationale for dierent levels of detail is as follows. 1) Near future plans need to be implemented soon, while far future plans can be rened or revised later. 2) More accurate sensor information is available about the system and its surroundings in the near future, and detailed planning is only rational in low uncertainty situations. 3) It has been shown that reducing the node density in the later parts of xed horizon optimal control problems gives a very small reduction in the solution quality of the rst part of the trajectory. The reduced level of detail in the later parts of a plan can increase the eciency of the RHC in two ways. If the discretization is made sparse by removing nodes, fewer computations are necessary, and if the discretization is made sparse by spreading the last nodes over a longer time-horizon, the performance will be improved.

  • 46481.
    Ögren, Petter
    et al.
    Swedish Defence Res. Agency, Stockholm.
    Svenmarck, Peter
    Swedish Defence Res. Agency, Stockholm.
    A New Control Mode for Teleoperated Differential Drive UGVs2007Ingår i: PROCEEDINGS OF THE 46TH IEEE CONFERENCE ON DECISION AND CONTROL, VOLS 1-14, 2007, 446-471 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper proposes a control mode that enables the users of teleoperated non-holonomic differential drive unmanned ground vehicles (UGVs) to interact with the unmanned vehicles in a new way. By introducing an intermediate control layer, a user interface that is very similar to so-called first person shooter (FPS) computer games, e.g. Doom and Half Life, can be created. The advantages of such interfaces is that they are intuitive, and that literally millions of potential future UGV-operators already have spent hundreds of hours training with them. The control mode gives the user direct control of the position and orientation of the on-board camera, while the actual orientation of the vehicle is abstracted away using feedback linearization. Thus, the idea is similar to using inverse kinematics to directly control the position and orientation of a robot arm gripper. The paper first describes the predominant direct vehicle control model, as well as the FPS interfaces. It is then shown how the proper choice of intermediate control layer can make the two equivalent

  • 46482.
    Ögren, Petter
    et al.
    Swedish Defence Research Agency (FOI).
    Winstrand, Maja
    Swedish Defence Research Agency (FOI).
    Combining Path Planning and Target Assignment to Minimize Risk in a SEAD Mission2005Konferensbidrag (Refereegranskat)
  • 46483.
    Ögren, Petter
    et al.
    Department of Autonomous Systems Swedish Defence Research Agency.
    Winstrand, Maja
    Minimizing Mission Risk in Fuel Constrained UAV Path Planning2008Ingår i: Journal of Guidance Control and Dynamics, ISSN 0731-5090, Vol. 31, nr 5, 1497-1500 s.Artikel i tidskrift (Refereegranskat)
  • 46484.
    Ögren, Petter
    et al.
    Swedish Defence Research Agency (FOI).
    Wirkander, Sven-Lennart
    Swedish Defence Research Agency (FOI).
    Stefansson, Anna
    Swedish Defence Research Agency (FOI).
    Pelo, Johan
    Swedish Defence Research Agency (FOI).
    Formulation and Solution of the UAV Paparazzi Problem2006Konferensbidrag (Refereegranskat)
    Abstract [en]

    Many UAV path planning problems dealing with multiple targets are formulated as instances of classical optimization problems such as the Traveling Salesperson Problem (TSP), Vehicle Routing Problem (VRP), and the Assignment Problem (AP). In their basic forms, all these problems minimize the length of the flight path to be flown by the UAVs. Even though this is often a reasonable choice, we argue that in instances when the targets are able to hide, or move, an objective function accounting for the target value, as well as the chance of actually finding the target is more natural. In some sense, the problem is similar to the one faced by a Paparazzi photographer, deciding where to go to get snapshots of non cooperative celebrities. Hence we formulate the so-called Paparazzi utility function, and show how it can be applied to UAV path planning problems similar to the TSP, VRP and AP

  • 46485.
    Öh, Rickard
    Linköpings universitet, Institutionen för datavetenskap.
    Analysis and implementation of remote support for ESAB’s welding systems: using WeldPoint and web services2009Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis was written on behalf of ESAB Research and Development department, in LaxåSweden. One of ESAB’s product areas is developing various welding systems.Today if ESAB’s customers experience a problem with one of their welding systems they callESAB’s service center. If the problem seems to have been caused by software, or if it requireslog files to be analyzed, ESAB needs a way to get this system information from the customer’swelding system to ESAB’s employees.One of the goals with this project thesis was to perform an analysis answering how the systeminformation should be sent, stored and what unit in the customer’s welding system that shouldsend it. Another goal was to implement the solution that the analysis presented.The analysis shows that WeldPoint in combination with a web service is the best way to sendthe system information from the customer’s welding system. WeldPoint is a PC control and logsoftware connected to the customer’s welding system. A web service provides a serviceinterface enabling clients to interact with a web server. Clients communicate with the webservice using HTTP, this means that clients can easily communicate across firewalls and othernetwork obstacles.The thesis work resulted in three different applications written in C#.NET. The first applicationis a simple form called WeldPoint Remote Support (WRS). This form extracts customerinformation, welding system information and log files from the customer and the customer’swelding system. All this information is called a case. The case is received by ESAB using thesecond application, WeldPoint Web service (WWS). WWS stores the received case in adatabase. The third application is called WeldPoint Remote Support Center (WRSC). Thisapplication is used by the ESAB employee’s to view the case sent from the customer’s weldingsystem.The above implementation has been tested and supports a robust and secure way to send andview the system information from the customer’s welding system. The conclusions showed thatall goals and requirements set by ESAB were met.

  • 46486.
    Öh, Rickard
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Utveckling av konsultkompetenssystem: Implementering av en kompetensdatabas för ett konsultbolag2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Syftet med detta examensarbete är att utreda/undersöka om det är möjligt att lagra och presentera medarbetares kompetens inom ett kunskapsintensivt företag. Initiativtagare till examensarbetet är konsultbolaget Nethouse Sverige AB.

    Allteftersom Nethouses medarbetarantal växer, blir det svårare att på ett bra sätt strukturera och sammanställa kompetensen och kapaciteten som finns inom företaget. Det blir också svårare att hålla koll på inom vilka områden enskilda medarbetare utvecklas.         

    • Svårt att sammanfatta kompetensen inom (medarbetare) och utanför (arbetssökande) Nethouse.
    • Uppdatering av konsultprofilen (Word-dokumentet) glöms lätt bort.
    • Svårt att söka efter medarbetare/arbetssökande med vissa kompetenser.

    För att på bästa sätt lösa problemen har en förstudie inom kravhantering genomförts. Förstudien resulterade i ett antal kravinsamlingsmetoder som sedan användes för att på bästa sätt extrahera de krav som fanns på ett kompetenssystem.

    Kraven uppfylldes genom att implementera en webbapplikation där varje medarbetare på Nethouse ges möjligheten att skapa en egen profil. En profil innehåller bland annat de uppdrag, kompetenser och roller som medarbetaren har erfarenhet av. Denna information är även sökbar och möjlighet finns att exportera profilen.

    Systemet kommer att spara Nethouses medarbetare mycket tid vid kompetens-sammanställning och sökning.

  • 46487.
    Öhberg, Torbjörn
    Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper.
    Undersökning av transformationsmetoder inom Ammenäs området, Uddevalla kommun2007Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats
    Abstract [sv]

    Inom Ammenäs området i Uddevalla kommun förekommer det spänningar/skillnader mellan fastigheternas gränspunkter som ligger i kommunens databas, och de gränspunktskoordinater som man får när man mäter med GNSS-utrustning, (detta trots det att båda systemen är i RT90 7.5 gon V).

    Databasens koordinater har tidigare transformerats från Uddevallas lokala system U38, till RT90 7.5 gon V, och i GNSS-utrustningen används också RT90 7.5 gon V.

    För att få ett homogent och överensstämmande koordinatsystem måste dagens stomnät och gränspunkter transformeras om till det system som GNSS-utrustningen använder (RT90 7.5 gon V).

    Jag har provat ett antal olika transformationssamband för att komma fram till vilken metod som ger bäst resultat.

    När det är så stora spänningar som i detta fall är den bästa metoden för att få ett bra resultat, att mäta flera mindre områden och transformera dem var för sig.

    När man har fått fram en acceptabel noggrannhet på gränspunkterna, kan man utföra kommunala mätningsuppdrag med koordinater som kommer från GNSS-utrustningen, vilket var syftet med examensarbetet.

  • 46488.
    Öhgren, Annika
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Data- och elektroteknik.
    Developing an Ontology for Wood-related Industry: An Experience Report2004Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Ontologies are widely used as a technique for representation and reuse of knowledge. This paper summarizes experiences and results of a project within ontology development, with wood-related industry as application sector. One major aspect of the project was the selection of a suitable methodology for ontology development. In a literature study existing methodologies were analyzed with respect to their suitability for small-scale application contexts. As no existing methodology was fully adequate, an improved methodology was proposed. The main intention was to reduce development time and effort to meet the demands of small-scale application contexts. The improved methodology was applied and evaluated in the project, i.e. in the development of an ontology for wood-related industry. The main conclusion is that the methodology was adequate for the project, but some aspects could be elaborated and further investigated, such as reuse of already existing ontologies.

  • 46489.
    Öhgren, Annika
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Data- och elektroteknik.
    Ontology Development and Evolution: Selected Approaches for Small-Scale Application Contexts2004Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This report presents a literature study concerning three areas, Ontology Development Methodologies, Ontology Evolution, and Ontologies in Small and Medium-Sized Enterprises. The objectives were to find out and summarize what has been done so far in the different areas, as well as to find out what has not yet been done, and thereby discover new possible research areas. Ontologies are widely used as a technique for representation and reuse of knowledge. We believe that ontologies can be used in small and medium-sized enterprises and help companies by supporting knowledge sharing, reuse of knowledge, inter-operability, and much more. The main conclusion is that a lot of work has been put into Ontology Development, many methodologies are very mature and have been used in practice. Still, not all of them cover the aspects we are interested in, e.g. reuse of already existing ontologies and covering the whole life cycle. In Ontology Evolution, the main focus is on keeping an ontology and its dependents consistent, and it does not concern when to make changes, or what to actually change. Ontology use in small and medium-sized enterprises is not so common, but some experiences exist.

  • 46490.
    Öhgren, Annika
    Linköpings universitet, Institutionen för datavetenskap, MDA - Human Computer Interfaces. Linköpings universitet, Tekniska högskolan.
    Towards an Ontology Development Methodology for Small and Medium-sized Enterprises2009Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    This thesis contributes to the research field information logistics. Information logistics aims at improving information flow and at reducing information overload by providing the right information, in the right context, at the right time, at the right place through the right channel.

    Ontologies are expected to contribute to reduced information overload and solving information supply problems. An ontology is created to form some kind of shared understanding for the involved stakeholders in the domain at hand. By using this semantic structure you can further build applications that use the ontology and support the employee by providing only the most important information for this person.

    During the last years, there has been an increasing number of successful cases in which industrial applications successfully use ontologies. Most of these cases however, stem from large enterprises or IT-intensive small or medium-sized enterprises (SME). The current ontology development methodologies are not tailored for SME and their specific demands and preferences, such as that SME prefer mature technologies, and show a clear preference for to a large extent standardised solutions. The author proposes a new ontology development methodology, taking the specific characteristics of SME into consideration. This methodology was tested in an application case, which resulted in a number of concrete improvement ideas, but also the conclusion that further specialisation of the methodology was needed, for example for a specific usage area or domain. In order to find out in which direction to specify the methodology a survey was performed among SME in the region of Jönköping.

    The main conclusion from the survey is that ontologies can be expected to be useful for SME mainly in the area of product configuration and variability modelling. Another area of interest is document management for supporting project work. The area of information search and retrieval can also be seen as a possible application field, as many of the respondents of the survey spend much time finding and saving information.

  • 46491.
    Öhgren, Annika
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Informationsteknik.
    Sandkuhl, Kurt
    Do SME Need Ontologies?: Results from a Survey among Small and Medium-sized Enterprises2008Ingår i: Proceedings of the 10th International Conference on Enterprise Information Systems - ICEIS 2008, 2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    During the last years, an increasing number of successful cases of using ontologies in industrial application scenarios have been reported, the majority of these cases stem from large enterprises. The intention of this paper is to contribute to an understanding of potentials and limits of ontology-based solutions in small and medium-sized enterprises (SME). The focus is on identifying application areas for ontologies, which motivate the development of specialised ontology construction methods. The paper is based on results from a survey performed among 113 SME in Sweden, most of them from manufacturing industries. The results of the survey indicate a need from SME in three application areas: (1) management of product configuration and variability, (2) information search and retrieval, and (3) management of project documents.

  • 46492.
    Öhgren, Annika
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Informationsteknik.
    Sandkuhl, Kurt
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsområde Informationsteknik.
    Information Overload in Industrial Enterprises - Results of an Empirical Investigation2008Ingår i: Proceedings of the 2nd European Conference on Information Management and Evaluation, Reading: Academic Publishing Limited , 2008, 343-350 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    The work presented is part of the research field information logistics, which investigates and develops concepts and technologies for improving information flow in organisations. The intention of this paper is to contribute to an understanding of information management problems in enterprises, and also improvement potentials of current information systems. The paper presents results of a study focusing on information overload in industrial enterprises, an area that previously has attracted little academic attention. Two areas are investigated: is information overload perceived as a problem in enterprises, and which application areas of enterprise information management should be prioritised for improvement activities? The survey was sent to 436 enterprises in the South of Sweden, most of them small and medium-sized enterprises, and received 164 valid responses. The sample used for the paper includes industrial enterprises from manufacturing, construction, and electronics industries, which accounts for approximately 80% of the responses.When analysing the data from the study, the paper follows the opinion of various scholars in the field that the complexity of an application case is an essential parameter to take into account when deciding on improvement potential. The more complex the application scenario is, the more likely is the usefulness of IT solutions for improving information flow. Research on complexity of projects proposes to define complexity as “consisting of many varied interrelated parts”, to distinguish between organisational and technological complexity, and to operationalise this in terms of “differentiation and interdependence”.One result of the study is a clear indication that information overload is perceived as a problem in industrial enterprises, which surfaces in problems such as finding the right information needed for a work task, and in the time needed to structure and store information. Furthermore, the results indicate two application areas that offer improvement potential: information management with focus on search and retrieval, and management of product information.

  • 46493.
    Öhgren, Jonny Karlsson
    Blekinge Tekniska Högskola, Institutionen för arbetsvetenskap och medieteknik.
    Sjukvårdsrådgivningen i Karlshamn, Blekinge Län,: Från utredning till verklighet, om processen att införskaffa ett system2002Självständigt arbete på grundnivå (kandidatexamen)Studentuppsats (Examensarbete)
    Abstract [sv]

    This Batchelor?s Thesis concerns 20 points at the MDA-program (People, Computers and Work) at Blekinge Institute of Technology in Ronneby, Sweden. 10 points concerns Computer Science and 10 points Human Work Science. The thesis is about the process of starting a new department of Blekingesjukhuset [Blekinge Hospital] in Karlshamn, Blekinge called Sjukvårdsrådgivningen [Health Care Advice Bureau]. The thesis starts with a description of the ethnographical methods used, followed by the process of establishing the department. In this new department, the nurses are using a computer based system called Teleråd, developed by TietoEnator. The thesis takes up the issues of how the department uses this system today and concerns what ?user-friendliness? is. The end of the thesis contains an evaluation of the visions of the founders of the new service and how/if the visions have become reality.

  • 46494. Öhlen, P
    et al.
    Skubic, B
    Rostami, A
    Fiorani, M
    Monti, P
    Ghebretensae, Z
    Mårtensson, J
    RISE., Swedish ICT, Acreo.
    Wang, K
    Wosinska, L
    Data Plane Control Architectures for 5G Transport Networks2016Ingår i: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 34, nr 6, 1501-8 s.Artikel i tidskrift (Refereegranskat)
  • 46495.
    Öhlin, Anton
    et al.
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för datavetenskap, fysik och matematik, DFM.
    Viking, Sebastian
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för datavetenskap, fysik och matematik, DFM.
    MPLS kontra traditionell IP-routing: en jämförelse av resursåtgång2011Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Multi Protocol Label Switching (MPLS) är en routingteknik som blir allt vanligare i dagens nätverk. Vid implementation av MPLS i nätverk är det grundläggande att hårdvaran har tillräckligt hög prestanda för att hantera tekniken. Om så inte är fallet kan det leda till negativa konsekvenser såsom paketförluster eller i värsta fall att routern havererar. Syftet med arbetet var att ta reda på hur processorbelastningen på en router skiljer sig när MPLS var implementerat jämfört med traditionell IP-routing. Routingprotokollen BGP, OSPF och RIP användes tillsammans med de olika routingteknikerna för att se vilket av dessa som krävde minst processorkraft.

    För att ta reda på hur processorbelastningen påverkades skapades en experimentmiljö. Varje routingprotokoll konfigurerades tillsammans med MPLS respektive traditionell IP-routing, vilket gav oss sex olika scenarion. Trafik skickades sedan genom nätverket med hjälp av applikationen Ostinato för att belasta enheterna.

    Resultatet av testerna visade att processorbelastningen blev högre för MPLS än för traditionell IP-routing. Det gällde för samtliga routingprotokoll. Det routingprotokoll som tillsammans med MPLS lyckades hålla processorbealstningen lägst var BGP, medans OSPF orsakade högst processorbelastning. Skillnaden mellan routingprotokollen OSPF och RIP var marginell.

  • 46496. Öhlin, David
    et al.
    Carlson, Rolf
    KTH, Tidigare Institutioner, Tal, musik och hörsel.
    Data-driven formant synthesis2004Ingår i: Proceedings FONETIK 2004: The XVIIth Swedish Phonetics Conference / [ed] Peter Branderud, Hartmut Traunmüller, Stockholm University, 2004, 160-163 s.Konferensbidrag (Övrigt vetenskapligt)
  • 46497.
    Öhlin, Petra
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Prioritizing Tests with Spotify’s Test & Build Data using History-based, Modification-based & Machine Learning Approaches2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis intends to determine the extent to which machine learning can be used to solve the regression test prioritization (RTP) problem. RTP is used to order tests with respect to probability of failure. This will optimize for a fast failure, which is desirable if a test suite takes a long time to run or uses a significant amount of computational resources. A common machine learning task is to predict probabilities; this makes RTP an interesting application of machine learning. A supervised learning method is investigated to train a model to predict probabilities of failure, given a test case and a code change. The features investigated are chosen based on previous research of history- based and modification-based RTP. The main motivation for looking at these research areas is that they resemble the data provided by Spotify. The result of the report shows that it is possible to improve how tests run with RTP using machine learning. Nevertheless, a much simpler history- based approach is the best performing approach. It is looking at the history of test results, the more failures recorded for the test case over time, the higher priority it gets. Less is sometimes more. 

  • 46498.
    Öhlund, Elinor
    et al.
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska fakulteten.
    Wang, William
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska fakulteten.
    Phung, Gullis
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska fakulteten.
    Olsson, Jonas
    Lundqvist, Felix
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska fakulteten.
    Hultberg, Dag
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska fakulteten.
    Fixcher, Max
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska fakulteten.
    Back, Hampus
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska fakulteten.
    Design och implementation av en e-butik med en personifierbar produkt för att uppnå nytta och effektivitet: Utveckling av e-butiken Coffe Creation2017Självständigt arbete på grundnivå (kandidatexamen), 12 poäng / 18 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Syftet med den här studien är att finna faktorer som gör en e-butik med personifierbara produkter användbar i form av effektivitet och nytta. Processen fram till slutprodukten har gjorts med en iterationsbaserad user-centered design-metod där utvecklarna under arbetets gång har haft en kontinuerlig dialog med slutanvändaren. Designmässiga val har gjorts utifrån återkoppling från användartester vilket har resulterat i en slutsats om att det finns fem faktorer som är viktiga att ha i åtanke då en e-butik för personifierbara produkter ska utvecklas. Att applikationens syfte och funktion presenteras för användaren visade sig vara viktigt för såväl nytta som effektivitet. Användarens förståelse om hur ett val som tas i applikationen kommer att påverka produkten är kopplat till nytta, och applikationens återkoppling kring ett val som har gjorts är kopplat till effektivitet. En väl utarbetad hierarki för det flöde användaren går igenom vid anpassning av en personifierad produkt är en kritisk faktor för effektivitet. Den sista faktorn är relaterad till ett begrepp som har benämnts alternativa köpflöden. Detta handlar främst om att det kan finnas en användarnytta med att utgå från förinställda produkter vid anpassning, istället för att skapa en ny produkt från grunden.

  • 46499.
    Öhlund, Mikael
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Metodutvärdering av ett implementationsprojekt: En leverantörs perspektiv på en implementationsmetod för affärssystem2012Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Affärssystem är idag mer aktuellt än tidigare. Ett affärssystem automatiserar en verksamhets kärnaktiviteter såsom produktion, Human Resources, bokföring och redovisning, och leverantörshantering genom användandet av Best Practice för att möjliggöra snabbare och effektivare beslutstagande, kostnadsminskning och ge en bättre styrning av verksamheten. Att införa ett affärssystem kan medföra fördelar såväl som nackdelar för verksamheten om införandet eller implementationen inte blir lyckad. Det finns ett flertal metoder utvecklade för att assistera under implementationen av ett affärssystem varav en av dessa har undersökts. Arbetet har genomförts med hjälp av datainsamling följt av empiriska iakttagelser. Genom fallstudien undersöktes hur väl implementationsmetoden har agerat stödjande för studieprojektet. Fallstudien genomfördes genom telefonintervjuer med personer som är väl insatta i projektet på övergripande nivå. Informanternas åsikter visar på att det finns områden där metoden inte har tagit hänsyn i undersökningen. Dessa områden är att inte ta hänsyn till klientens förväntingar på systemet, misslyckas med att höja klientens kompetens tidigt, klientnatur, upphandlingsnatur och organisationsstruktur. Utifrån detta identifierades två separata huvudområden: Metodspecifika- och klientspecifika problem. Problemen som har existerat i studieprojektet härrör inte endast metoden Ascendant for SAP utan till stor del den specifika klienten.

  • 46500.
    Öhlund, Sten-Erik
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling. Linköpings universitet, Filosofiska fakulteten.
    Interoperability Capability to interoperate in a shared work practice using information infrastructures: studies in ePrescribing2017Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    The ability to interoperate between systems, people, and organizations is considered an important issue within eHealth in order to deliver patient centered care. The achieving and improving of interoperability is a complex undertaking involving the evolution of an information infrastructure, sharing of knowledge and resources, governance of the interoperation between organizations, people and work practices, and handling of economic and legal matters.

    This thesis contributes with practical knowledge on improving interoperability, based on active participation in and empirical studies of improving interoperability in ePrescribing. A case study describes and analyzes the evolution of ePrescribing in Sweden since the early pioneering years in 1980s, its growth and consolidation before the reregulation of the pharmacy market in 2009. Apractical theory on ePrescribing is presented. A unique field experimental study measuring improvement of interoperability in ePrescribing, before and after a major intervention to improve the quality of ePrescriptions between 2004 and 2009 is presented.

    Furthermore, a practical theory on interoperation and interoperability is presented. Interoperability is seen as the exercised capability of organizations through their agents to interoperate in a shared work practice in an effective, efficient, and satisfactory manner based on a common ground in a mediated, prescriptive, and non-personal communicative setting using an information infrastructure for mediating interoperation.

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