Ändra sökning
Avgränsa sökresultatet
976977978979980981982 48901 - 48950 av 49228
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 48901.
    Öberg, Jonas
    Högskolan i Kalmar, Institutionen för kommunikation och design.
    Comparative study of operating system security using SELinux and Systrace2009Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis makes a comparative study of the security systemsSystrace (used primarily with OpenBSD) and SELinux (usedexclusively with Linux), trying to answer the question as to whichtype of security is offered by each respective system, and wheneach should be used. The key difference between SELinux andSystrace seems to be their mode of operation, where SELinux,built around the LSM framework in the Linux kernel, works withtype enforcement on files, sockets and other objects, whereasSystrace works on a strict system call basis. The two systems areseen to serve two different purposes which sometimes overlap,but in just as many cases provide solutions for entirely differentquality priorities.

  • 48902.
    Öberg, Kim
    Linköpings universitet, Institutionen för datavetenskap, Interaktiva och kognitiva system. Linköpings universitet, Tekniska högskolan.
    HORN - Hank and OpenDRIVE Road Networks: An editor for creating HANK scenarios while working with OpenDRIVE2012Självständigt arbete på grundnivå (kandidatexamen), 12 hpStudentuppsats (Examensarbete)
    Abstract [en]

    HORN is a solution to the problem of how to implement scenarios in a more efficient way than was previously possible allowing researchers who wish to create scenarios for HANK the ability to quicker implement larger scenarios than was previously possible.

    OpenDRIVE is an open standard for road networks that is believed to be the way forward and Horn is an attempt at unifying OpenDRIVE scenarios with HANK - the driving simulator currently in use at Link\"{o}pings Universitet, thus futureproofing all work done to implement scenarios.

    Before HORN HANK scenarios were laboriously constructed with a really bad program or by hand and HORN tries to make the process far less painful.

    This thesis describes how to work with the Road Network Editor program HORN ("Hank and OpenDRIVE Road Networks") that was developed for working with HANK's scenarios as well as my experience implementing it and some of the fascinating rules for how to draw some exotic two dimensional geometries I found out about as I worked on HORN.

  • 48903.
    Öberg, Lena-Maria
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Creation and maintenance of traceability2011Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 48904.
    Öberg, Lena-Maria
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    En metod för att rekonstruera processer genom bevarande av handlingar2008Ingår i: Arkiv samhälle och forskning, ISSN 0349-0505, Vol. 01, s. 6-14Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    The new Swedish method for archival description will be introduced the first of July 2008. The new method is built upon process modeling and will document how records are connected to the processes where the records have been created and managed. The aim with this article is to describe a method to reconstruct processes. The method has been used in a study where I have studied which components that make it possible to reconstruct processes afterwards. The method could serve as a complement to traditional process modeling methods which often builds upon seminars where participators together design todays and tomorrows processes. The method that has been used in the study presented in this paper is from this viewpoint different because it strives to understand and describe how the process has looked like. The method includes three steps; Data collection in archives, process modeling and validations seminars. The result from using the method has showed that it could be a helpful tool.

  • 48905.
    Öberg, Lena-Maria
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Factors that improve traceability between information and processes over time2011Ingår i: Journal of Organisational Transformation and Social Change, ISSN 1477-9633, E-ISSN 2040-056XArtikel i tidskrift (Refereegranskat)
  • 48906.
    Öberg, Lena-Maria
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Forskning och Utveckling kring teknisk information2007Rapport (Övrigt vetenskapligt)
  • 48907.
    Öberg, Lena-Maria
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Identifiering och värdering av framtida krav kvalitetskrav på teknisk information2008Rapport (Övrigt vetenskapligt)
  • 48908.
    Öberg, Lena-Maria
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Information management for long-term maintenance of technical atifacts -: Requirements on traceablity in technical information2010Ingår i: The international Multi-conference on Complexity, Informatics and Cybernetics: IMCIC 2010 / [ed] Wiliam Lesso, 2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    Technical artifacts with a long lifetime put special requirement on management of technical information. The information need to be managed and maintained to keep it understandable and valid for as long as needed and this put high requirements on effective information management because it is necessary to keep track of which technical information that is valid for which variant of technical artifact.  This article is based on a study where requirements on technical information was in focus and especially requirements that concern traceability. Seven requirements have been identified and it have been concluded that those requirements basically concern between which object that the traceability concern, that it matters if a requirement is put from internal or external need or if the requirement concern objects from different information systems. The conclusion is that a requirement is harder to reach if the connections between objects are separated in different information systems.

  • 48909.
    Öberg, Lena-Maria
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Is document in process supportive information systems prepared for long-term preservation?2005Ingår i: Proceedings of the 2005 International Business Information Management Conference July 5 - 7, 2005 Lisbon, Portugal,, 2005Konferensbidrag (Övrigt vetenskapligt)
  • 48910.
    Öberg, Lena-Maria
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Metadata use in document management systems which support business processes.2008Ingår i: Archives & Social Studies: A Journal of Interdisciplinary Research, ISSN 1988-0626, Vol. 2, nr 1, s. 217-249Artikel i tidskrift (Refereegranskat)
  • 48911.
    Öberg, Lena-Maria
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Needed Components to Reconstruct Processes2006Ingår i: Archiving 2006: Final Program and Proceedings, Springfield: IS & T , 2006, s. 165-168Konferensbidrag (Refereegranskat)
    Abstract [en]

    In many organizations there is changeover from paper-based records to electronic records. This is a natural process, when more and more information and documents are created by the usage of computer based information system. The problem is that many organizations implement information systems for managing electronic records, which not takes recordkeeping requirements into consideration to full extent. Record keeping system must fulfil requirements regarding context. This is necessary because it have to be possible to make interpretations of records, over time. The aim of this paper is to describe how much and what kind of traces of the handling process there are in paper based archives. A qualitative empirical study will be conducted. The method include interpretations of paper based records with an aim to model processes. The study includes comparisons between periods, before and after implementation of computerized systems. The process models will be analyzed and validated by dialog seminars. The contributions of this paper are; firstly descriptions of process elements that make it possible to interpret processes and records afterwards; secondly descriptions of differences of those process-elements between different time periods, thirdly: the process models will be important inputs when designing efficient digital record keeping in integrated e-services.

  • 48912.
    Öberg, Lena-Maria
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Traceability between S1000D and SCORM: lessons learnedManuskript (preprint) (Övrigt vetenskapligt)
  • 48913.
    Öberg, Lena-Maria
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Traceable Information Systems: Factors That Improve Traceability Between Information and Processes Over Time2007Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Preservation of information is not a new issue but preservation of digital information has a relatively short history. Since the 60’s when computers began to be used within administration, digital information that has had to be preserved over time.The problem addressed in this research is how to preserve understandable information over time. Information is context dependent, which means that without context it is not possible to use the information. Process is one part of the context. And an important issue when preserving information is then to be able to trace an information

    object to the process where in it has been created and managed. Associating information to a particular process creates the possibility of relating information objects to each other and also to the context in which the information has been created and used. The aim of this thesis is to identify and structure factors that can improve the traceability between information and processes over time. A set of factors based on case studies and a set of analytical methods are presented that can improve the traceability over time. These factors have been identified and structured by the use of the Synergy-4 model. They have been identified within four different spheres namely: competence, management, organization/procedure and technology. The factors have further been structured in three different time states namely: creation time, short and middle term and long-term. The research concludes that there are a lot of factors influencing ability to preserve information. Preservation issues include selection of metadata standards, organizational culture, lack of understanding from management and formalization of documents. The conclusion is that if an organization wants to succeed in preserving traceable information they have to build strategies that cover the issues from a range of different angles. This thesis suggests that crucial angles are competence, management, organization/procedure

    and technology. Furthermore, the strategies must be in place at the stage of creationof the information objects.

  • 48914.
    Öberg, Lena-Maria
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Borglund, Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Operational use of Records2006Ingår i: proceedings of IRIS 29, 2006Konferensbidrag (Refereegranskat)
    Abstract [en]

    The changeover from paper based records to electronic records in many organizations involves no longer only recordkeeping experts, but also people from the information system community. Electronic records are created, managed and preserved within information systems and methods to support this must be developed. In this paper the operational use of records and how that use might affect development of information systems supporting recordkeeping are of interest. This paper is empirical grounded with data from four previously performed studies. The results are compared with two existing models of recordkeeping; the life-cycle model and the Record Continuum Model. This paper presents a result where operational records use can be described in three categories; decision support, intelligence support and information retrieval. The operational use of records is widespread, difficult to predict, and not always related to a record�s original purpose of use. A record has an operational value that not always has been an issue of interest by the recordkeeping community. This altogether motivates both that a proactive approach is necessary when designing information system supporting recordkeeping, but also that the Record Continuum Model is more applicable when dealing with electronic records.

  • 48915.
    Öberg, Lena-Maria
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Borglund, Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    What are the Characteristics of Records?2005Ingår i: Proceedings of the 28th Information Systems Research Seminar in Scandinavia, 2005, s. 55-76Konferensbidrag (Refereegranskat)
    Abstract [en]

    Project documentations, minutes of meeting, emergency plans, and inspection reports are all examples of records, recorded information. One key characteristic of records is preservation, records may be preserved for long time. There is a changeover from paper based records to electronic records in many organizations. Electronic records are part of computerbased information systems and need to be handled automatically following archival requirements to remain trustworthiness during preservation. The ISO definition of record is abstract and give limited support in understanding what a record is on operational level. Knowledge valuable for practitoners involved in design and development of information systems. The aim of this paper is to identify different classes of records, and identify categories of characteristics or variables for these records, i.e. make records operational. This paper is based on a qualitative case study performed at four different organizations. Empirical data was collected from multiple sources in order to understand records. More than 100 different records were identified, which together made ten classes of records. The classes together with the characteristics resulted in an object oriented based diagram, a visualization of the analysis of the empirical data.

  • 48916.
    Öberg, Lena-Maria
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    Borglund, Erik
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    What are the Characteristics of Records?2006Ingår i: International Journal of Public Information Systems, ISSN 1653-4360, Vol. 2, nr 1, s. 55-76Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Project documentation, minutes of meetings, emergency plans, and inspection reports are all examples of records, recorded information. There is a changeover from paper-based records to electronic records in many organizations and these organizations often implement information systems managing electronic records that only take archival requirements into consideration to some extent, if at all. This is a problem that makes preservation of electronic records difficult. The aim of this paper is to describe the characteristics of records, based on a study of empirical data and archival theory. It is essential to identify and understand the characteristics of a record in order to manage and preserve records in computerised systems. Knowledge of what characteristics a record has is one way to make it possible to formalize records. Formalization at different levels is needed for computerized management of records. This paper is based on a qualitative case study performed at four different organizations in Sweden. Empirical data was collected from multiple sources within each organization and resulted in five groups of characteristics with several sublevels. The empirical data were compared with recordkeeping and archival theory. Based on this study the essential characteristics of records were identified as context, form, organization, structure and version/copy.

  • 48917.
    Öberg, Lena-Marie
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för informationsteknologi och medier.
    To Capture and Preserve Documents in Processes2005Ingår i: Information Management in modern enterprise - Issues & solutions: Proceedings of the 2005 international business information management conference July 5-7, 2005, Lisbon, Portugal, IBIMA , 2005, s. 181-183Konferensbidrag (Refereegranskat)
  • 48918.
    Öberg, Tomas
    Linköpings universitet, Institutionen för datavetenskap.
    Design av databassystem för testresultat från Tor-systemet2004Självständigt arbete på grundnivå (yrkesexamen)Studentuppsats
    Abstract [en]

    This master’s thesis was performed at PartnerTech AB in Åtvidaberg. It addresses the problem of managing test results obtained from testing electronics manufactured by PartnerTech. PartnerTech has developed a test system, called Tor, which performs tests on manufactured boards and stores the test results in files. The Tor system consists of both hardware and software part, where the software runs on an ordinary PC with MS DOS/Windows 2000. The effects on the existing Tor system that this thesis implies are minimal.

    This work focuses on a way of storing the produced test files in a database. In this work a data model has been developed, implemented, and evaluated together with a system that imports test files into the database and a graphical user interface that allows a user to easily search and browse the stored test results. It is also possible to print test reports from the Tor system. For implementing the database system Microsoft SQL Server 2000 was chosen as database server and an XML based data format was chosen to import and export data to and from the database. Two alternative graphical user interface applications were developed and compared - one server based on Microsoft IIS and one client based in Microsoft Access. For advanced data manipulation certain parts of the system were developed in Microsoft Excel.

  • 48919.
    Öberg, Tomas
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för data- och systemvetenskap.
    Server-vs klientgenererade webbapplikationer: Enjämförelse ur ett usabilityperspektiv2017Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta arbete avser titta närmare på och jämföra två   vanliga tillvägagångssätt för att skapa interaktivitet via webbsidor idag,   nämligen server- och klientsidegenerering. Det övergripande syftet med   undersökningen är att hjälpa till att utröna vilket tillvägagångssätt som är   bäst anpassat för att generera maximal affärsnytta till minsta möjliga   tidskostnad. Perspektivet som används för att mäta detta är usability ur   utvecklarsynpunkt. Tiden att sätta sig in i ett ramverk kan bero på ett   flertal aspekter och därför har en avgränsat scenario satts upp och   individuella delar har utvärderats sida vid sida i ramverken JSF och   Angular.io. Tillsammans med intervjuer av utvecklares samlade upplevelse har   ett resultat kunnat sammanställas. Detta resultat talar vare sig för eller   emot endera tillvägagångssätt då båda tekniker har sina för- och nackdelar.   Det som dock har varit mest framträdande i jämförelsen är att införandet av   designmönstret Model View Controller i ett ramverk för klientsidegenerering   så som Angular.io. Detta ger en likartad upplevelse i usability som ett   motsvarande för serversidegenererande så som JSF, vilket är bra ur   effektivitetssynpunkt. Dock upplevs bristen på relevanta felmeddelanden som   ett stort problem på klientsidegenererande ramverk och något som sticker ut   negativt i jämförelsen.

  • 48920.
    Öberg, Viktor
    Högskolan i Skövde, Institutionen för informationsteknologi.
    EVOLUTIONARY AI IN BOARD GAMES: An evaluation of the performance of an evolutionary algorithm in two perfect information board games with low branching factor2015Självständigt arbete på grundnivå (kandidatexamen), 15 poäng / 22,5 hpStudentuppsats (Examensarbete)
    Abstract [en]

    It is well known that the branching factor of a computer based board game has an effect on how long a searching AI algorithm takes to search through the game tree of the game. Something that is not as known is that the branching factor may have an additional effect for certain types of AI algorithms.

    The aim of this work is to evaluate if the win rate of an evolutionary AI algorithm is affected by the branching factor of the board game it is applied to. To do that, an experiment is performed where an evolutionary algorithm known as “Genetic Minimax” is evaluated for the two low branching factor board games Othello and Gomoku (Gomoku is also known as 5 in a row). The performance here is defined as how many times the algorithm manages to win against another algorithm.

    The results from this experiment showed both some promising data, and some data which could not be as easily interpreted. For the game Othello the hypothesis about this particular evolutionary algorithm appears to be valid, while for the game Gomoku the results were somewhat inconclusive. For the game Othello the performance of the genetic minimax algorithm was comparable to the alpha-beta algorithm it played against up to and including depth 4 in the game tree. After that however, the performance started to decline more and more the deeper the algorithms searched. The branching factor of the game may be an indirect cause of this behaviour, due to the fact that as the depth increases, the search space increases proportionally to the branching factor. This increase in the search space due to the increased depth, in combination with the settings used by the genetic minimax algorithm, may have been the cause of the performance decline after that point.

  • 48921.
    Öberg, Viktor
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Middleware med Google Web Toolkit2012Självständigt arbete på grundnivå (högskoleexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta examensarbete har utförts i samarbete med företaget Systemagic AB. Systemagic är ett teknikföretag vars expertis ligger inom mjukvaruutveckling inom IPTV-teknologi. Detta innefattar bland annat utveckling av middleware till digitalboxar, också kallade Set-top-boxar.

    Middleware är den mjuk- och hårdvaruinfrastruktur som sammankopplar de olika delarna av ett IPTV-system. Det är ett distribuerat operativt system som både finns på operatörens servrar samt i slutanvändarens digitalbox. Då det idag ställs allt högre krav på funktionalitet och dynamik från beställare blir utvecklingen av ett modernt middleware mycket resurskrävande. Systemagic anser att en stor bidragande orsak till den resurskrävande utvecklingsprocessen kan kopplas till användningen av scriptspråket JavaScript och är därför intresserade av alternativa metoder.

    Google Web Toolkit (GWT) är ett Java-ramverk som kan användas för att på ett snabbt och smidigt sätt utveckla interaktiva webbapplikationer. Detta möjliggörs genom att all utveckling sker i Java. Slutprodukten efter kompilering är standard-kompatibel HTML och JavaScript, helt oberoende av Java.

    Detta examensarbete har gått ut på att undersöka möjligheten att använda Java och GWT för att underlätta och potentiellt snabba upp utvecklingen av ett middleware. Målet var att undersöka om GWT kan användas rakt av för att ta fram den del av ett middleware som återfinns i slutanvändarens box, en så kallad portal, eller om ramverket måste anpassas för att de mest grundläggande funktionerna hos en box ska kunna implementeras. Rapporten beskriver frågeställningar, tillvägagångssätt, problem och  svårigheter som uppstod, de lösningar som använts samt en analys och diskussion av resultatet.

  • 48922.
    Öbom, Anton
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Bratteby, Adrian
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Maskininlärning för att förutspå churn baserat på diskontinuerlig beteendedata2017Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Denna rapport handlar om att utforska fälten maskininlärning och digital marknadsföring, genom att använda maskininlärning som ett redskap för att förutspå churn i en typ av företag med diskontinuerlig beteendedata.

    För att förutspå churn finns relativt simpla "out of the box"-modeller, som support vector machines och random forests, som används för att nå acceptabla resultat. För att nå liknande resultat som i arbeten där churn utförs på kontinuerlig beteendedata konstaterar denna rapport att framtida arbeten forska på vilka utvärderingsmetriker som är mest lämpade.

    I rapporten presenteras också hur dessa upptäckter kan kommersialiseras och hur företaget Sellpy kan tjäna på att förutspå churn.

  • 48923.
    Öborn, Malin
    et al.
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT.
    Berg, David
    Karlstads universitet, Fakulteten för ekonomi, kommunikation och IT.
    Utbyggnad av Diamond: ett generellt dokumenthanteringssystem2012Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 48924.
    Ödling, David
    et al.
    KTH, Skolan för teknikvetenskap (SCI).
    Österlund, Arvid
    KTH, Skolan för teknikvetenskap (SCI).
    Factorisation of Latent Variables in Word Space Models: Studying redistribution of weight on latent variables2014Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Målet med alla semantiska fördelningsmodeller (DSMs) är en skalbaroch precis representation av semantiska relationer. Nya rön från Bullinaria & Levy (2012) och Caron (2001) indikerar att man kan förbättra prestandan avsevärt genom att omfördela vikten ifrån principalkomponenterna med störst varians mot de lägre. Varför metoden fungerar är dock fortfarande oklart, delvis på grund av höga beräkningskostnader för PCA men även på grund av att resultaten strider mot tidigare praxis.

    Vi börjar med att replikera resultaten i Bullinaria & Levy (2012) för att sedan fördjupa oss i resultaten, både kvantitativt och kvalitativt, genom att använda oss av BLESS testet.

    Huvudresultaten av denna studie är verifiering av 100% på TOEFL testet och ett nytt resultat på en paradigmatisk variant av BLESStestet på 91.5%. Våra resultat tyder på att en omfördelning av vikten ifrån de första principalkomponenterna leder till en förändring i fördelningensins emellan de semantiska relationerna vilket delvis förklarar förbättringen i TOEFL resultaten. Vidare finner vi i enlighet med tidigare resultat ingen signifikant relation mellan ordfrekvenser och viktomfördelning.

    Utifrån dessa resultat föreslår vi en rad experiment som kan ge vidare insikt till dessa intressanta resultat.

  • 48925.
    Ödling, Ola
    et al.
    Erisoft AB, Sweden.
    Wallin, Stefan
    Erisoft AB, Sweden.
    Building MIB Applications1994Ingår i: IEEE Network Operations and Management Symposium: Symposium Record : Wednesday, February 16: Sessions 11 - 20, Piscataway, NJ: IEEE Communications Society, 1994, Vol. 2, s. 565-575Konferensbidrag (Refereegranskat)
  • 48926.
    Öfjäll, Kristoffer
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska fakulteten.
    Adaptive Supervision Online Learning for Vision Based Autonomous Systems2016Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Driver assistance systems in modern cars now show clear steps towards autonomous driving and improvements are presented in a steady pace. The total number of sensors has also decreased from the vehicles of the initial DARPA challenge, more resembling a pile of sensors with a car underneath. Still, anyone driving a tele-operated toy using a video link is a demonstration that a single camera provides enough information about the surronding world.  

    Most lane assist systems are developed for highway use and depend on visible lane markers. However, lane markers may not be visible due to snow or wear, and there are roads without lane markers. With a slightly different approach, autonomous road following can be obtained on almost any kind of road. Using realtime online machine learning, a human driver can demonstrate driving on a road type unknown to the system and after some training, the system can seamlessly take over. The demonstrator system presented in this work has shown capability of learning to follow different types of roads as well as learning to follow a person. The system is based solely on vision, mapping camera images directly to control signals.  

    Such systems need the ability to handle multiple-hypothesis outputs as there may be several plausible options in similar situations. If there is an obstacle in the middle of the road, the obstacle can be avoided by going on either side. However the average action, going straight ahead, is not a viable option. Similarly, at an intersection, the system should follow one road, not the average of all roads.  

    To this end, an online machine learning framework is presented where inputs and outputs are represented using the channel representation. The learning system is structurally simple and computationally light, based on neuropsychological ideas presented by Donald Hebb over 60 years ago. Nonetheless the system has shown a cabability to learn advanced tasks. Furthermore, the structure of the system permits a statistical interpretation where a non-parametric representation of the joint distribution of input and output is generated. Prediction generates the conditional distribution of the output, given the input.  

    The statistical interpretation motivates the introduction of priors. In cases with multiple options, such as at intersections, a prior can select one mode in the multimodal distribution of possible actions. In addition to the ability to learn from demonstration, a possibility for immediate reinforcement feedback is presented. This allows for a system where the teacher can choose the most appropriate way of training the system, at any time and at her own discretion.  

    The theoretical contributions include a deeper analysis of the channel representation. A geometrical analysis illustrates the cause of decoding bias commonly present in neurologically inspired representations, and measures to counteract it. Confidence values are analyzed and interpreted as evidence and coherence. Further, the use of the truncated cosine basis function is motivated.  

    Finally, a selection of applications is presented, such as autonomous road following by online learning and head pose estimation. A method founded on the same basic principles is used for visual tracking, where the probabilistic representation of target pixel values allows for changes in target appearance.

  • 48927.
    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.

  • 48928.
    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.

  • 48929.
    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, s. 137-156Konferensbidrag (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.

  • 48930.
    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.

  • 48931.
    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)
  • 48932.
    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)
  • 48933.
    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)
  • 48934.
    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, s. 137-156Kapitel 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.

  • 48935.
    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, s. 218-231Konferensbidrag (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.

  • 48936.
    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, s. 136-143Konferensbidrag (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. 

  • 48937.
    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.

  • 48938.
    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)
  • 48939.
    Öfverstedt, Johan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för visuell information och interaktion. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Bildanalys och människa-datorinteraktion.
    Sladoje, Nataša
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för visuell information och interaktion. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Bildanalys och människa-datorinteraktion.
    Lindblad, Joakim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för visuell information och interaktion. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Bildanalys och människa-datorinteraktion.
    Distance between vector-valued fuzzy sets based on intersection decomposition with applications in object detection2017Ingår i: Mathematical Morphology and its Applications to Signal and Image Processing, Springer, 2017, Vol. 10225, s. 395-407Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present a novel approach to measuring distance between multi-channel images, suitably represented by vector-valued fuzzy sets. We first apply the intersection decomposition transformation, based on fuzzy set operations, to vector-valued fuzzy representations to enable preservation of joint multi-channel properties represented in each pixel of the original image. Distance between two vector-valued fuzzy sets is then expressed as a (weighted) sum of distances between scalar-valued fuzzy components of the transformation. Applications to object detection and classification on multi-channel images and heterogeneous object representations are discussed and evaluated subject to several important performance metrics. It is confirmed that the proposed approach outperforms several alternative single-and multi-channel distance measures between information-rich image/ object representations.

  • 48940.
    Öfverstedt, Linn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för visuell information och interaktion.
    Why go headless – a comperative study between traditional CMS and the emerging headless trend2018Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    There has been an exponential increase in the number of websites, digital channels and consequently digital content in the last years. Not only are the number of websites increasing but they are also becoming more complex, therefore it is no longer feasible to handle content and code with the same tools. Content Management Systems (CMS) are the solution to this problem and offers a way of managing content. The market today offers a broad variety of solutions that each have their own advantages, one of the more common being WYSWYG-functionality which often means that the functionality and the presentation of the content are tightly coupled. "Headless" CMS are a new way of doing things and offers the user a way of managing content without presenting them with a way of displaying the content. The different types of CMS present advantages and disadvantages from a user centred point of view as well as from a technical one. The thesis aims to explore these perspectives and form a hypothesis based on the studied cases. The study presents a set of aspects that based on the context in which the CMS is used and implemented can be perceived as either advantages or disadvantages. "Headless" CMS however shows a tendency to be the preferable choice where the editors have a technical background and the developing part values an agnostic approach when implementing a CMS, whereas a traditional CMS with WYSIWYG functionality tends to be more favourable where stability and editorial freedom are valued.

  • 48941.
    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.

  • 48942.
    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.

  • 48943.
    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, s. 1274-1279Konferensbidrag (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.

  • 48944.
    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, s. 1951-1955Konferensbidrag (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

  • 48945.
    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.

  • 48946.
    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

  • 48947.
    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, s. 847-851Artikel 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

  • 48948.
    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

  • 48949.
    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.

  • 48950.
    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.

976977978979980981982 48901 - 48950 av 49228
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf