https://www.mdu.se/

mdh.sePublikasjoner
Endre søk
Begrens søket
12 1 - 50 of 83
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Ahlberg, Carl
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik. Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Asplund, Lars
    Mälardalens högskola, Akademin för innovation, design och teknik. Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Campeanu, Gabriel
    Mälardalens högskola, Akademin för innovation, design och teknik. Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ciccozzi, Federico
    Mälardalens högskola, Akademin för innovation, design och teknik. Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekstrand, Fredrik
    Mälardalens högskola, Akademin för innovation, design och teknik. Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik. Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Feljan, Juraj
    Mälardalens högskola, Akademin för innovation, design och teknik. Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Gustavsson, Andreas
    Mälardalens högskola, Akademin för innovation, design och teknik. Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Sentilles, Séverine
    Mälardalens högskola, Akademin för innovation, design och teknik. Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Svogor, Ivan
    FOI, University of Zagreb.
    Segerblad, Emil
    The Black Pearl: An Autonomous Underwater Vehicle2013Rapport (Annet vitenskapelig)
    Abstract [en]

    The Black Pearl is a custom made autonomous underwater vehicle developed at Mälardalen University, Sweden. It is built in a modular fashion, including its mechanics, electronics and software. After a successful participation at the RoboSub competition in 2012 and winning the prize for best craftsmanship, this year we made minor improvements to the hardware, while the focus of the robot's evolution shifted to the software part. In this paper we give an overview of how the Black Pearl is built, both from the hardware and software point of view.

  • 2.
    Ahlberg, Carl
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekstrand, Fredrik
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Spampinato, Giacomo
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Asplund, Lars
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    GIMME2 - An embedded system for stereo vision and processing of megapixel images with FPGA-acceleration2015Inngår i: 2015 International Conference on ReConFigurable Computing and FPGAs, ReConFig 2015, 2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents GIMME2, an embedded stereovision system, designed to be compact, power efficient, cost effective, and high performing in the area of image processing. GIMME2 features two 10 megapixel image sensors and a Xilinx Zynq, which combines FPGA-fabric with a dual-core ARM CPU on a single chip. This enables GIMME2 to process video-rate megapixel image streams at real-time, exploiting the benefits of heterogeneous processing.

  • 3.
    Ahlberg, Carl
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Leon, Miguel
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekstrand, Fredrik
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    The Genetic Algorithm Census TransformManuskript (preprint) (Annet vitenskapelig)
  • 4.
    Ahlberg, Carl
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Leon, Miguel
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekstrand, Fredrik
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    The genetic algorithm census transform: evaluation of census windows of different size and level of sparseness through hardware in-the-loop training2021Inngår i: Journal of Real-Time Image Processing, ISSN 1861-8200, E-ISSN 1861-8219, nr 3, s. 539-559Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Stereo correspondence is a well-established research topic and has spawned categories of algorithms combining several processing steps and strategies. One core part to stereo correspondence is to determine matching cost between the two images, or patches from the two images. Over the years several different cost metrics have been proposed, one being the Census Transform (CT). The CT is well proven for its robust matching, especially along object boundaries, with respect to outliers and radiometric differences. The CT also comes at a low computational cost and is suitable for hardware implementation. Two key developments to the CT are non-centric and sparse comparison schemas, to increase matching performance and/or save computational resources. Recent CT algorithms share both traits but are handcrafted, bounded with respect to symmetry, edge lengths and defined for a specific window size. To overcome this, a Genetic Algorithm (GA) was applied to the CT, proposing the Genetic Algorithm Census Transform (GACT), to automatically derive comparison schemas from example data. In this paper, FPGA-based hardware acceleration of GACT, has enabled evaluation of census windows of different size and shape, by significantly reducing processing time associated with training. The experiments show that lateral GACT windows produce better matching accuracy and require less resources when compared to square windows.

  • 5.
    Ahlberg, Carl
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Leon, Miguel
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekstrand, Fredrik
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Unbounded Sparse Census Transform using Genetic Algorithm2019Inngår i: 2019 IEEE WINTER CONFERENCE ON APPLICATIONS OF COMPUTER VISION (WACV), IEEE , 2019, s. 1616-1625Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The Census Transform (CT) is a well proven method for stereo vision that provides robust matching, with respect to object boundaries, outliers and radiometric distortion, at a low computational cost. Recent CT methods propose patterns for pixel comparison and sparsity, to increase matching accuracy and reduce resource requirements. However, these methods are bounded with respect to symmetry and/or edge length. In this paper, a Genetic algorithm (GA) is applied to find a new and powerful CT method. The proposed method, Genetic Algorithm Census Transform (GACT), is compared with the established CT methods, showing better results for benchmarking datasets. Additional experiments have been performed to study the search space and the correlation between training and evaluation data.

  • 6.
    Ahlberg, Carl
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Lidholm, Jörgen
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Ekstrand, Fredrik
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Spampinato, Giacomo
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Asplund, Lars
    Mälardalens högskola, Akademin för innovation, design och teknik.
    GIMME - A General Image Multiview Manipulation Engine2011Inngår i: Proceedings of the International Conference on ReConFigurable Computing and FPGAs (ReConFig 2011), Los Alamitos, Calif: IEEE Computer Society, 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents GIMME (General Image Multiview Manipulation Engine), a highly flexible reconfigurable stand-alone mobile two-camera vision platform with stereo-vision capability. GIMME relies on reconfigurable hardware (FPGA) to perform application-specific low to medium-level image-processing at video rate. The Qseven-extension enables additional processing power. Thanks to its compact design, low power consumption and standardized interfaces (power and communication), GIMME is an ideal vision platform for autonomous and mobile robot applications.

  • 7.
    Ameri, Afshin
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Curuklu, Baran
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Miloradović, Branko
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Planning and Supervising Autonomous Underwater Vehicles through the Mission Management Tool2020Inngår i: Global OCEANS 2020 OCEANS, 2020Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Complex underwater missions involving heterogeneous groups of AUVs and other types of vehicles require a number of steps from defining and planning the mission, orchestration during the mission execution, recovery of the vehicles, and finally post-mission data analysis. In this work the Mission Management Tool (MMT), a software solution for addressing the above-mentioned services is proposed. As demonstrated in the real-world tests the MMT is able to support the mission operators. The MMT hides the complex system consisting of software solutions, hardware, and vehicles from the user, and allows intuitive interaction with the vehicles involved in a mission. The tool can adapt to a wide spectrum of missions assuming different types of robotic systems and mission objectives.

  • 8.
    Ameri, Afshin
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Miloradović, Branko
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Curuklu, Baran
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Papadopoulos, Alessandro
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Dreo, J.
    Computational Biology dept., Université Paris Cité, Institut Pasteur, Paris, France.
    Interplay of Human and AI Solvers on a Planning Problem2023Inngår i: Conf. Proc. IEEE Int. Conf. Syst. Man Cybern., Institute of Electrical and Electronics Engineers Inc. , 2023, s. 3166-3173Konferansepaper (Fagfellevurdert)
    Abstract [en]

    With the rapidly growing use of Multi-Agent Systems (MASs), which can exponentially increase the system complexity, the problem of planning a mission for MASs became more intricate. In some MASs, human operators are still involved in various decision-making processes, including manual mission planning, which can be an ineffective approach for any non-trivial problem. Mission planning and re-planning can be represented as a combinatorial optimization problem. Computing a solution to these types of problems is notoriously difficult and not scalable, posing a challenge even to cutting-edge solvers. As time is usually considered an essential resource in MASs, automated solvers have a limited time to provide a solution. The downside of this approach is that it can take a substantial amount of time for the automated solver to provide a sub-optimal solution. In this work, we are interested in the interplay between a human operator and an automated solver and whether it is more efficient to let a human or an automated solver handle the planning and re-planning problems, or if the combination of the two is a better approach. We thus propose an experimental setup to evaluate the effect of having a human operator included in the mission planning and re-planning process. Our tests are performed on a series of instances with gradually increasing complexity and involve a group of human operators and a metaheuristic solver based on a genetic algorithm. We measure the effect of the interplay on both the quality and structure of the output solutions. Our results show that the best setup is to let the operator come up with a few solutions, before letting the solver improve them.

  • 9.
    Astrand, Elaine
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Extraction of working memory load and the importance of understanding the temporal dynamics2017Inngår i: International IEEE/EMBS Conference on Neural Engineering, NER, IEEE Computer Society , 2017, s. 641-647, artikkel-id 8008433Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Working memory processing is central for higher-order cognitive functions. Although the ability CP to access and extract working memory load has been proven feasible, the temporal resolution is low and cross-task generalization is poor. In this study, EEG oscillatory activity CP was recorded from sixteen healthy subjects while they performed two versions of the visual n-back task. Observed effects in the working memory-related EEG oscillatory activity CP, specifically in theta, alpha and low beta power, are significantly different in the two tasks (i.e. two categories of visual stimuli) and these differences are greatest after image onset. Furthermore, cross-task generalization can be obtained by concatenating both tasks and although similar performances are observed before and after image onset, this study highlights the complexity CP of working memory processing related to different categories of visual stimuli, particularly after image onset, that are crucial to understand, in order to interpret the extraction of working memory load.

  • 10.
    Bergblomma, Marcus
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Ekström, Martin
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Gerdtman, Christer
    Motion Control AB, Västerås, Sweden .
    Lindén, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik.
    A wireless low latency control system for harsh environments2012Inngår i: IFAC Proceedings Volumes (IFAC-PapersOnline): Vol. 11, PART 1, 2012, s. 17-22Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The use of wireless communication technologies in the industry offer severaladvantages. One advantage is the ability to deploy sensors where they previously could noteasily be deployed, for instance on parts that rotate. To use wireless communication in industrialcontrol loops, demands on reliability and latency requirements has to be met. This in anenvironment that may be harsh for radio communication. This work presents a reliable, lowlatency wireless communication system. The system is used in a wireless thyristor control loopin a hydro power plant generator. The wireless communication is based on Bluetooth radiomodules. The work shows a latency analysis together with empirical hardware based latencyand packet error rate measurements. The background noise of a hydro power plant station isalso investigated. The average latency between the Bluetooth modules for the proposed systemis 5.09 ms. The packet error rate is 0.00288 for the wireless low latency control system deployedin a hydro power plant.

  • 11.
    Bergblomma, Marcus
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Ekström, Martin
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Garcia Castaño, Javier
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Lindén, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Wireless ECG network2009Inngår i: WORLD CONGRESS ON MEDICAL PHYSICS AND BIOMEDICAL ENGINEERING, VOL 25, PT 5, 2009, s. 244-247Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents a time synchronized wireless ECG sensor network with reliable data communication. Wireless ECG systems are a popular research area where several research groups have presented point-to-point solutions. Alongside the wireless ECG research, the wireless sensor network research has created an increasing interest for secure, low power and predictable network applications. Combining these research areas is a natural step for the evolution of secure wireless monitoring of physiological parameters. In this study the Bluetooth radio standard has been chosen for its versatility. This paper focuses on both the hardware and the software development for a functional multihop ECG network using Bluetooth. The presented wireless ECG network is reliable up to link loss and is easily configured to send more or different types of signals. The system has been tested and verified for secure multihop communication.

  • 12.
    Berglin, Lena
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Lindén, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Monitoring health and activity by smartwear2005Konferansepaper (Annet vitenskapelig)
  • 13.
    Castano, Javier Garcia
    et al.
    Mälardalens högskola, Institutionen för datavetenskap och elektronik.
    Andreasson, J.
    Mälardalens högskola, Institutionen för datavetenskap och elektronik.
    Ekström, Mikael
    Mälardalens högskola, Institutionen för datavetenskap och elektronik.
    Wrzesniewski, H.
    Ahlbom, H.
    Bäcklund, Ylva
    Mälardalens högskola, Institutionen för datavetenskap och elektronik.
    Wireless industrial sensor monitoring based on BluetoothTM2003Inngår i: INDIN 2003: IEEE INTERNATIONAL CONFERENCE ON INDUSTRIAL INFORMATICS, PROCEEDINGS, 2003, s. 65-72Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    This paper describes a novel Bluetooth(TM)-based wireless solution for industrial sensor monitoring. The solution enables wireless monitoring systems improving earlier Bluetooth(TM) implementations where mobility is not supported A distributed wireless sensor network is described with the sensor wireless interface, the architecture, protocols and algorithms used. Achieved results are: (1) Multi mobile wireless sensor monitoring with Bluelooth(TM). (2) Deployment of a distributed architecture for wireless sensors with global access.

  • 14.
    Dust, Lukas
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Gu, Rong
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Mubeen, Saad
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Seceleanu, Cristina
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    A Model-Based Methodology for Automated Verification of ROS 2 Systems2024Konferansepaper (Fagfellevurdert)
    Abstract [en]

    To simplify the formal verification of ROS 2-based applications, in this paper, we propose a novel approach to the automation of their model-based verification using model-driven engineering techniques. We propose a methodology starting with ROS 2 execution traces, generated by ROS2_tracing and using models and model transformations in Eclipse to automatically initialize pre-defined formal model templates in UPPAAL, with system parameters. While the methodology targets the simplification of formal verification for robotics developers as users, the implementation is at an early stage and the toolchain is not fully implemented and evaluated. Hence, this paper targets tool developers and researchers to give a first overview of the underlying idea of automating ROS 2 verification.

    Hence, we propose a toolchain that supports verification of implemented and conceptual ROS 2 systems, as well as iterative verification of timing and scheduling parameters. We propose using four different model representations, based on the ROS2_tracing output and self-designed Eclipse Ecore metamodels to model the system from a structural and verification perspective. The different model representations allow traceability throughout the modeling and verification process.Last, an initial proof of concept is implemented containing the core elements of the proposed toolchain and validated given a small ROS 2 system. 

  • 15.
    Dust, Lukas
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Gu, Rong
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Mubeen, Saad
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Seceleanu, Cristina
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    UPPAAL-based Modeling and Verification of ROS 2 Multi-Threaded Execution and Operating System ReservationsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    In this paper, we propose a formal modeling approach in uppaal to simulate and verify multi-threaded robotics middleware execution based on ROS 2. In the modeling process, we consider middleware-specific scheduling by creating formal models that simulate the execution behavior of a ROS 2-based system. Furthermore, we show how to model potential underlying operating system's influences on execution by modeling reservation servers. We propose timed automata templates to model the multi-threaded execution of ROS 2 systems and the reservations of the underlying operating system in uppaal.We show how to utilize the created templates to simulate a ROS 2 application. We demonstrate the application of the formal models and model checking in various ROS 2 experiments. Furthermore, we validate the created models by comparing the observed execution traces in experiments on ROS 2 systems and the simulated traces of our models.Overall, this paper showcases the application and usability of model-based verification of distributed middleware applications, including internal scheduling and influences of underlying operating system actions.

  • 16.
    Dust, Lukas
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Gu, Rong
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Seceleanu, Cristina
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Mubeen, Saad
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Pattern-Based Verification of ROS 2 Nodes Using UPPAAL2023Inngår i: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), Springer Science and Business Media Deutschland GmbH , 2023, s. 57-75Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper proposes a pattern-based modeling and Uppaal-based verification of latencies and buffer overflow in distributed robotic systems that use ROS 2. We apply pattern-based modeling to simplify the construction of formal models for ROS 2 systems. Specifically, we propose Timed Automata templates for modeling callbacks in Uppaal, including all versions of the single-threaded executor in ROS 2. Furthermore, we demonstrate the differences in callback scheduling and potential errors in various versions of ROS 2 through experiments and model checking. Our formal models of ROS 2 systems are validated in experiments, as the behavior of ROS 2 presented in the experiments is also exposed by the execution traces of our formal models. Moreover, model checking can reveal potential errors that are missed in the experiments. The paper demonstrates the application of pattern-based modeling and verification in distributed robotic systems, showcasing its potential in ensuring system correctness and uncovering potential errors.

  • 17.
    Dust, Lukas
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Persson, Emil
    Ekström, Mikael
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Mubeen, Saad
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Dean, E.
    Chalmers University of Technology, Göteborg, Sweden.
    Quantitative analysis of communication handling for centralized multi-agent robot systems using ROS22022Inngår i: IEEE Conference on Industrial Informatics, ISSN 1935-4576, E-ISSN 2378-363X, Vol. 2022-July, s. 624-629Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multi-agent robot systems, specifically mobile robots in dynamic environments interacting with humans, e.g., assisting in production environments, have seen an increased interest over the past years. To better understand the ROS2 communication in a network with a high load of nodes, this paper investigates the communication handling of multiple robots to a single tracking node for centralized multi-agent robot systems using ROS2. Thereore, a quantitative analysis of two publisher-subscriber communication architectures and a comparative study between DDS vendors (CycloneDDS, FastDDS and GurumDDS) using ROS2 Galactic is performed. The architectures of consideration are a many-to-one approach, where multiple robots communicate to a central node over one topic, and the one-to-one communication approach, where multiple robots communicate over particular topics to a central node. Throughout this work, the increase in the number of robots at different publishing rates is simulated on a single computer for the different DDS vendors. A further simulation is done using a distributed setup with CycloneDDS. The simulations show that with an increase in the number of nodes, the average data age and the data miss ratio in the one-to-one approach were significantly lower than in the many-to-one approach. CycloneDDS was shown as the most robust regarding crashes and response time under system launch, while FastDDS showed better results regarding the data ageing. © 2022 IEEE.

  • 18.
    Dust, Lukas
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Persson, Emil
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Mubeen, Saad
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Seceleanu, Cristina
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Gu, Rong
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Experimental Evaluation of Callback Behavior in ROS 2 Executors2023Inngår i: IEEE Int. Conf. Emerging Technol. Factory Autom., ETFA, Institute of Electrical and Electronics Engineers Inc. , 2023Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Robot operating system 2 (ROS 2) is increasingly popular both in research and commercial robotic systems. ROS 2 is designed to allow real-time execution and data communication, enabling rapid prototyping and deployment of robotic systems. In order to predict and calculate execution times in ROS 2, one needs to analyze its internal scheduler, called executor. The executor has been updated in various distributions of ROS 2, which is shown to impact significantly the periodic execution invoked by the underlying operating system's timers, potentially causing unexpected latencies. To expose the mentioned impact due to executor differences, in this paper, we present an experimental evaluation of the execution behavior of ROS 2's schedulable entities, namely callbacks, among the existing versions of the executor. We visualize the differences of callback execution order via simulation, and we create design-level scenarios that impact the execution of periodically scheduled callbacks, negatively. Moreover, we show how such negative impact can be mitigated by using multi-threaded executors. Finally, we illustrate the observed behavior on a real-world centralized multi-agent robot system. Our work aims to raise awareness within the ROS 2 developer community, regarding possible problems of timer blocking, and propose a mitigation solution of the latter.

  • 19.
    Ekstrand, Fredrik
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Ahlberg, Carl
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Asplund, Lars
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Spampinato, Giacomo
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Resource Limited Hardware-based Stereo Matching for High-Speed Vision System2011Inngår i: ICARA 2011 - Proceedings of the 5th International Conference on Automation, Robotics and Applications, 2011, s. 465-469Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper proposes a limited implementation of areabasedstereo matching for minimal resource utilization. It shows that it is possible to achieve an acceptable disparity map without the use of expensive resources. The matching accuracy for the single-row SAD can even outperform that of its full-row counterpart. Additionally, it excels in terms of frame rate and resource utilization, and is highly suitable for real-time stereo-vision systems.

  • 20.
    Ekstrand, Fredrik
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Ahlberg, Carl
    Ekström, Mikael
    Asplund, Lars
    Spampinato, Giacomo
    Utilization and Performance Considerations in Resource Optimized Stereo Matching for Real-Time Reconfigurable Hardware2012Inngår i: VISAPP 2012 - Proceedings of the International Conference on Computer Vision Theory and Application, vol. 2, 2012, s. 415-418Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    This paper presents a set of approaches for increasing the accuracy of basic area-based stereo matching methods. It is targeting real-time FPGA systems for dense disparity map estimation. The methods are focused on low resource usage and maximized improvement per cost unit to enable the inclusion of an autonomous system in an FPGA. The approach performs on par with other area-matching implementations, but at substantially lower resource usage. Additionally, the solution removes the requirement for external memory for reconfigurable hardware together with the limitation in image size accompanying standard methods. As a fully piped complete on-chip solution, it is highly suitable for real-time stereo-vision systems, with a frame rate over 100 fps for Megapixel images.

  • 21.
    Ekstrand, Fredrik
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ahlberg, Carl
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Spampinato, Giacomo
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    High-speed segmentation-driven high-resolution matching2015Inngår i: Proceedings of SPIE - The International Society for Optical Engineering, vol. 9445, 2015, Vol. 9445, s. Article number 94451Y-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper proposes a segmentation-based approach for matching of high-resolution stereo images in real time. The approach employs direct region matching in a raster scan fashion influenced by scanline approaches, but with pixel decoupling. To enable real-time performance it is implemented as a heterogeneous system of an FPGA and a sequential processor. Additionally, the approach is designed for low resource usage in order to qualify as part of unified image processing in an embedded system.

  • 22.
    Ekstrand, Fredrik
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ahlberg, Carl
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Spampinato, Giacomo
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Towards an Embedded Real-Time High Resolution Vision System2014Inngår i: ADVANCES IN VISUAL COMPUTING (ISVC 2014), PT II / [ed] Bebis, G Boyle, R Parvin, B Koracin, D McMahan, R Jerald, J Zhang, H Drucker, SM Kambhamettu, C ElChoubassi, M Deng, Z Carlson, M, SPRINGER-VERLAG BERLIN , 2014, s. 541-550Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper proposes an approach to image processing for high performance vision systems. Focus is on achieving a scalable method for real-time disparity estimation which can support high resolution images and large disparity ranges. The presented implementation is a non-local matching approach building on the innate qualities of the processing platform which, through utilization of a heterogeneous system, combines low-complexity approaches into performing a high-complexity task. The complementary platform composition allows for the FPGA to reduce the amount of data to the CPU while at the same time promoting the available informational content, thus both reducing the workload as well as raising the level of abstraction. Together with the low resource utilization, this allows for the approach to be designed to support advanced functionality in order to qualify as part of unified image processing in an embedded system.

  • 23.
    Ekström, Martin
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Bergblomma, Marcus
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Lindén, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Ekström, Mikael
    Edith Cowan University, Bunbury, Australia.
    A Bluetooth Radio Energy Consumption Model for Low Duty-Cycle Applications2012Inngår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 61, nr 3, s. 609-617Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents a realistic model of the radio energy consumption for Bluetooth-equipped sensor nodes used in a low-duty-cycle network. The model is based on empirical energy consumption measurements of Bluetooth modules. This model will give users the possibility to optimize their radio communication with respect to energy consumption while sustaining the data rate. This paper shows that transmission power cannot always be directly related to energy consumption. Measurements indicate that, when the transmission power ranges from $-$5 to $+$10 dBm, the difference in consumed energy can be detected for each transmission peak in the sniff peak. However, the change is negligible for the overall energy consumption. The nonlinear behavior of the idle state for both master and slave when increasing the interval and number of attempts is presented. The energy consumption for a master node is in direct relation to the number of slaves and will increase by approximately 50% of the consumption of one slave per additional slave, regardless of the radio setting.

    Fulltekst (pdf)
    fulltext
  • 24.
    Ekström, Martin
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Bergblomma, Marcus
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Lindén, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Comparison study of ZigBee and Bluetooth with regards to power consumption, packet-error-rate and distanceManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    This paper present a empirical measurement comparison study of ZigBee and Bluetooth. The parameters investigated are power consumption, packet-error-rate or retransmissions and distance in different environments. This study shows the differences and similarities for the two different short range radio technologies. A measurement set-up and procedure that makes it possible to investigate power consumption of the radio module, retransmissions and packet-error-rate as well as ambient noise is presented. For both the Bluetooth and the ZigBee modules used in this study the distance itself have no influence of the power consumption. However the retransmission rate and packet-error-rate have a large influence on the power consumption. This study have show that the environment has a great impact on the range of the radio modules and the behaviour concerning the retransmission rate and packet-error-rate.

    Fulltekst (pdf)
    Comparison study of ZigBee and Bluetooth with regards to power consumption, packet-error-rate and distance
  • 25.
    Ekström, Martin
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Bergblomma, Marcus
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Lindén, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Development of Programmable Micro Power Meter Testbed for Radio ModulesManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    This paper presents the POMPOM testbed for high precision power consumption \textit{in situ} measurements for interchangeable radio modules.The main requirements for the development have been;

    Interchangeable radio modules to enable the same hardware testbed to be used independently of the radio standard used make comparison studies possible.

    The testbed should be programmable so that the need for hardware development should be minimized. The testbed must be able to act as a controller for the communication and simultaneously make accurate \textit{in situ} measurements of the energy consumption of the radio.

    The required sample rate must be at least 50 kSamples per second. The range of the current measurement should cover at least 0.2~$\mu$Ampere to 60~mAmpere with at least 14-bit resolution.

    Mobility, low cost and small size are vital for the testbed. It must be possible to deploy several measurement testbeds to act as sensor nodes in a wireless sensor network to capture the behavior of the entire network.

    The results for test measurement setup for POMPOM is presented to illustrate a typical usage of the testbed. The results presented show how the testbed can be used to investigate the correlation between distance, packet-error-rate and current consumption for a Zigbee radio.

    Fulltekst (pdf)
    Development of Programmable Micro-Power-Meter Testbed for Radio Modules
  • 26.
    Ekström, Martin
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Blom, Marcus
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Garcia Castaño, Javier
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Lindén, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Bluetooth energy characteristics in wireless sensor networks2008Inngår i: 2008 3RD INTERNATIONAL SYMPOSIUM ON WIRELESS PERVASIVE COMPUTING, VOLS 1-2, 2008, s. 198-202Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper a measurement system to create an experimental model and a tool box for simulations concerning both the energy consumption and the time aspect when creating wireless sensor networks using Bluetooth 2.0 + enhanced data rate has been developed. Further energy and time characteristics for critical events when using Bluetooth 2.0 in wireless sensor networks are investigated experimentally, with the main events; create connection, send data, receive data, and idle state. Results show that when allowing higher latencies for the connection in the Wireless Sensor Networks the power consumption drops drastically when using low power mode as sniff.

  • 27.
    Ekström, Mikael
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik. Uppsala University, Sweden.
    Hartmann, Ola
    Uppsala University, Sweden.
    Karlsson, Erik
    Uppsala University, Sweden.
    Lidström, Erik
    Uppsala University, Sweden.
    Granberg, Per
    Uppsala University, Sweden.
    Nygren, M
    Mälardalens högskola, Akademin för innovation, design och teknik. Stockholm University, Sweden.
    Antiferromagnetism in Zn-doped La2CuO4 as observed by muon spin resonance spectroscopy2001Inngår i: Physical Review B - Condensed Matter and Materials Physics, ISSN 0163-1829, Vol. 64, nr 18, s. 1845221-1845226, artikkel-id 184522Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The local fields seen by positive muons implanted in Zn-doped La2CuO4 show a distribution with a main peak attributed to muon sites far from the Zn ions and a satellite structure corresponding to muons residing closer to the Zn. The temperature dependence indicates a strong loss of magnetic order for Cu moments near the Zn atoms. The data can be understood in terms of a model where a Zn ion not only introduces a vacancy in the magnetic Cu lattice but also creates a RKKY-type disturbance. The electron spin polarization around the Zn ions induces a change of the magnetic moments on surrounding Cu ions. The AF lattice is found to be strongly perturbed within a radius of 10 Angstrom around each Zn ion. Possible consequences for the superconductivity of the corresponding Sr-doped materials are discussed.

  • 28.
    Folke, Mia
    et al.
    Mälardalens högskola, Institutionen för datavetenskap och elektronik.
    Hök, Bertil
    Hök Instrument AB, Västerås, Sweden .
    Ekström, Mikael
    Mälardalens högskola, Institutionen för datavetenskap och elektronik.
    Bäcklund, Ylva
    Mälardalens högskola, Institutionen för datavetenskap och elektronik.
    End tidal carbon dioxide measurement using an electro acoustic sensor2004Inngår i: Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings, 2004, s. 3452-3455Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    End tidal carbon dioxide measurement with an electro-acoustic sensor is demonstrated. The sensor consists of an acoustic resonator coupled to a low cost electro-acoustic element. By simultaneous measurements with a reference sensor, the new device was tested on subjects performing exercise, hypo- and hyperventilation whereby the CO2 concentration ranged from 2.1 to 7.0 kPa. The output from the experimental device correlated well with the reference CO2 readings with a correlation coefficient of 0.976. Response time for expiration less than 0.8 seconds was noted. The new device could be useful in situations where selectivity to other gases is not important.

  • 29.
    Frasheri, Mirgita
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Cano-Garcia, Jose
    University of Malaga, Spain.
    Gonzalez-Parada, Eva
    University of Malaga, Spain.
    Curuklu, Baran
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Papadopoulos, Alessandro
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Urdiales, Cristina
    University of Malaga, Spain.
    Adaptive Autonomy in Wireless Sensor Networks2020Inngår i: Proceedings of the International Joint Conference on Autonomous Agents and Multiagent Systems, AAMAS, 2020, s. 375-383Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Moving nodes in a Mobile Wireless Sensor Network (MWSN) typically have two maintenance objectives: (i) extend the coverage of the network as long as possible to a target area, and (ii) extend the longevity of the network as much as possible. As nodes move and also route traffic in the network, their battery levels deplete differently for each node. Dead nodes lead to loss of connectivity and even to disengaging full parts of the network. Several reactive and rule-based approaches have been proposed to solve this issue by adapting redeployment to depleted nodes. However, in large networks a cooperative approach may increase performance by taking the evolution of node battery and traffic into account. In this paper, we present a hybrid agent-based architecture that addresses the problem of depleting nodes during the maintenance phase of a MWSN. Agents, each assigned to a node, collaborate and adapt their behaviour to their battery levels. The collaborative behavior is modeled through the willingness to interact abstraction, which defines when agents ask and give help to one another. Thus, depleting nodes may ask to be replaced by healthier counterparts and move to areas with less traffic or to a collection point. At the lower level, negotiations trigger a reactive navigation behaviour based on Social Potential Fields (SPF). It is shown that the proposed method improves coverage and extends network longevity in an environment without obstacles as compared to SPF alone.

    Fulltekst (pdf)
    fulltext
  • 30.
    Frasheri, Mirgita
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Curuklu, Baran
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Analysis of perceived helpfulness in adaptive autonomous agent populations2018Inngår i: Transactions on Computational Collective Intelligence XXVIII, Springer Verlag , 2018, Vol. 10780, s. 221-252Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Adaptive autonomy allows agents to change their autonomy levels based on circumstances, e.g. when they decide to rely upon one another for completing tasks. In this paper, two configurations of agent models for adaptive autonomy are discussed. In the former configuration, the adaptive autonomous behavior is modeled through the willingness of an agent to assist others in the population. An agent that completes a high number of tasks, with respect to a predefined threshold, increases its willingness, and vice-versa. Results show that, agents complete more tasks when they are willing to give help, however the need for such help needs to be low. Agents configured to be helpful will perform well among alike agents. The second configuration extends the first by adding the willingness to ask for help. Furthermore, the perceived helpfulness of the population and of the agent asking for help are used as input in the calculation of the willingness to give help. Simulations were run for three different scenarios. (i) A helpful agent which operates among an unhelpful population, (ii) an unhelpful agent which operates in a helpful populations, and (iii) a population split in half between helpful and unhelpful agents. Results for all scenarios show that, by using such trait of the population in the calculation of willingness and given enough interactions, helpful agents can control the degree of exploitation by unhelpful agents. © Springer International Publishing AG, part of Springer Nature 2018.

  • 31.
    Frasheri, Mirgita
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Curuklu, Baran
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Comparison Between Static and Dynamic Willingness to Interact in Adaptive Autonomous Agents2018Inngår i: Proceedings of the 10th International Conference on Agents and Artificial Intelligence, 2018, Vol. 1, s. 258-267Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Adaptive autonomy (AA) is a behavior that allows agents to change their autonomy levels by reasoning on their circumstances. Previous work has modeled AA through the willingness to interact, composed of willingness to ask and give assistance. The aim of this paper is to investigate, through computer simulations, the behavior of agents given the proposed computational model with respect to different initial configurations, and level of dependencies between agents. Dependency refers to the need for help that one agent has. Such need can be fulfilled by deciding to depend on other agents. Results show that, firstly, agents whose willingness to interact changes during run-time perform better compared to those with static willingness parameters, i.e. willingness with fixed values. Secondly, two strategies for updating the willingness are compared, (i) the same fixed value is updated on each interaction, (ii) update is done on the previous calculated value. The maximum number of completed tasks which need assistance is achieved for (i), given specific initial configurations.

  • 32.
    Frasheri, Mirgita
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Curuklu, Baran
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Papadopoulos, Alessandro
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Adaptive Autonomy in a Search and Rescue Scenario2018Inngår i: International Conference on Self-Adaptive and Self-Organizing Systems, SASO, Volume 2018-September, 15 January 2019, 2018, s. 150-155Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Adaptive autonomy plays a major role in the design of multi-robots and multi-agent systems, where the need of collaboration for achieving a common goal is of primary importance. In particular, adaptation becomes necessary to deal with dynamic environments, and scarce available resources. In this paper, a mathematical framework for modelling the agents' willingness to interact and collaborate, and a dynamic adaptation strategy for controlling the agents' behavior, which accounts for factors such as progress toward a goal and available resources for completing a task among others, are proposed. The performance of the proposed strategy is evaluated through a fire rescue scenario, where a team of simulated mobile robots need to extinguish all the detected fires and save the individuals at risk, while having limited resources. The simulations are implemented as a ROS-based multi agent system, and results show that the proposed adaptation strategy provides a more stable performance than a static collaboration policy. 

    Fulltekst (pdf)
    fulltext
  • 33.
    Frasheri, Mirgita
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Cürüklü, Baran
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Towards Collaborative Adaptive Autonomous Agents2017Inngår i: ICAART: PROCEEDINGS OF THE 9TH INTERNATIONAL CONFERENCE ON AGENTS AND ARTIFICIAL INTELLIGENCE, VOL 1, 2017, s. 78-87Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Adaptive autonomy enables agents operating in an environment to change, or adapt, their autonomy levels by relying on tasks executed by others. Moreover, tasks could be delegated between agents, and as a result decision-making concerning them could also be delegated. In this work, adaptive autonomy is modeled through the willingness of agents to cooperate in order to complete abstract tasks, the latter with varying levels of dependencies between them. Furthermore, it is sustained that adaptive autonomy should be considered at an agent's architectural level. Thus the aim of this paper is two-fold. Firstly, the initial concept of an agent architecture is proposed and discussed from an agent interaction perspective. Secondly, the relations between static values of willingness to help, dependencies between tasks and overall usefulness of the agents' population are analysed. The results show that a unselfish population will complete more tasks than a selfish one for low dependency degrees. However, as the latter increases more tasks are dropped, and consequently the utility of the population degrades. Utility is measured by the number of tasks that the population completes during run-time. Finally, it is shown that agents are able to finish more tasks by dynamically changing their willingness to cooperate.

  • 34.
    Frasheri, Mirgita
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Miloradović, Branko
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Curuklu, Baran
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Papadopoulos, Alessandro
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    GLocal: A Hybrid Approach to the Multi-Agent Mission Re-Planning Problem2020Rapport (Annet vitenskapelig)
    Abstract [en]

    Multi-robot systems can be prone to failures during plan execution, depending on the harshness of the environment they are deployed in. As a consequence, initially devised plans may no longer be feasible, and a re-planning process needs to take place to re-allocate any pending tasks. Two main approaches emerge as possible solutions, a global re-planning technique using a centralized planner that will redo the task allocation with the updated world state information, or a decentralized approach that will focus on the local plan reparation, i.e., the re-allocation of those tasks initially assigned to the failed robots.The former approach produces an overall better solution, while the latter is less computationally expensive.The goal of this paper is to exploit the benefits of both approaches, while minimizing their drawbacks. To this end, we propose a hybrid approach {that combines a centralized planner with decentralized multi-agent planning}. In case of an agent failure, the local plan reparation algorithm tries to repair the plan through agent negotiation. If it fails to re-allocate all of the pending tasks, the global re-planning algorithm is invoked, which re-allocates all unfinished tasks from all agents.The hybrid approach was compared to planner approach, and it was shown that it improves on the makespan of a mission in presence of different numbers of failures,as a consequence of the local plan reparation algorithm.

    Fulltekst (pdf)
    fulltext
  • 35.
    Frasheri, Mirgita
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Trinh, LanAnh
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Curuklu, Baran
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Failure Analysis for Adaptive Autonomous Agents using Petri Nets2017Inngår i: Proceedings of the 2017 Federated Conference on Computer Science and Information Systems, FedCSIS 2017, 2017, s. 293-297Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Adaptive autonomous (AA) agents are able to make their own decisions on when and with whom to share their autonomy based on their states. Whereas dependability gives evidence on whether a system, (e.g. an agent team), and its provided services are to be trusted. In this paper, an initial analysis on AA agents with respect to dependability is conducted. Firstly, AA is modeled through a pairwise relationship called willingness of agents to interact, i.e. to ask for and give assistance. Secondly, dependability is evaluated by considering solely the reliability attribute, which presents the continuity of correct services. The failure analysis is realized by modeling the agents through Petri Nets. Simulation results indicate that agents drop slightly more tasks when they are more willing to interact than otherwise, especially when the fail-rate of individual agents increases. Conclusively, the willingness should be tweaked such that there is compromise between performance and helpfulness.

  • 36.
    Ghaderi, Adnan
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Innovation och produktrealisering.
    Ahlberg, Carl
    Östgren, Magnus
    Mälardalens universitet.
    Ekstrand, Fredrik
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    FP-SLIC: A Fully-Pipelined FPGA Implementation of Superpixel ImageSegmentation2022Inngår i: Proceedings: 2022 25th Euromicro Conference on Digital System Design, DSD 2022, 2022, s. 109-117Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A superpixel segment is a group of pixels that carry similar information. The Simple Linear Iterative Clustering (SLIC) is a well-known algorithm for generating superpixels that offers a good balance between accuracy and efficiency. Nevertheless, due to its high computational requirements, the algorithm does not meet the demands of real-time embedded applications in terms of speed and resources. This paper proposes a fully-pipelined FPGA architecture of SLIC, dubbed FP-SLIC, that exhibits 1) a simplified and efficient algorithm of reduced computational complexity that facilitates algorithm development for FPGAs, 2) a fully pipelined FPGA design operating at 40MHz with a throughput of one pixel per cycle, and 3) a memory-efficient architecture that eliminates the requirement for external memory. Implementation results achieve 259 fps on the BSDS500 dataset, which is ≈ 8.6× more than the requirement for real-time performance (30 frames per second).

  • 37.
    Granstedt, Fredrik
    et al.
    Mälardalens universitet.
    Folke, Mia
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Hök, B.
    Hök Instrument AB, Västerås, Sweden.
    Bäcklund, Ylva
    Mälardalens universitet.
    Modelling of an electroacoustic gas sensor2005Inngår i: Sensors and Actuators B: Chemical, Vol. 104, nr 2, s. 311-311Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A theoretical model of an electroacoustic gas sensor has been designed and compared with experimental data. The sensor includes a piezoelectric element coupled to an acoustic resonator depending on the average molecular weight of the gas with respect to resonance frequency. The model is based on a transmission line coupled to a Butterworth van Dyke model of the piezoelectric element. The frequency characteristics of the sensor impedance was both simulated and measured on prototype sensors. The results indicate that the model provides an adequate description of overall sensor behaviour, and will constitute a useful design tool. Due to interdependencies of the model parameters, the precise quantification of sensor characteristics will either require highly accurate parameter data, or a considerably more complex model.

  • 38.
    Hanna, Atieh
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system. Research and Technology Development, Volvo Group Trucks Operations, Göteborg, Sweden.
    Bengtsson, K.
    Chalmers University of Technology, Göteborg, Sweden.
    Dahl, M.
    Chalmers University of Technology, Göteborg, Sweden.
    Eros, E.
    Chalmers University of Technology, Göteborg, Sweden.
    Götvall, P. -L
    Research and Technology Development, Volvo Group Trucks Operations, Göteborg, Sweden.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Industrial Challenges when Planning and Preparing Collaborative and Intelligent Automation Systems for Final Assembly Stations2019Inngår i: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA, Institute of Electrical and Electronics Engineers Inc. , 2019, s. 400-406Konferansepaper (Fagfellevurdert)
    Abstract [en]

    During the last five decades, automation and robotics have transformed the automotive industry by increasing efficiency and improving the product quality. However, future trucks that will be autonomous, electrical and connected will require a completely new type of flexibility and intelligence in the production systems, especially in the final assembly. To handle the increased complexity of the products, production processes and logistic systems, final assembly must be transformed into collaborative and intelligent automation systems. These systems will include collaborative and deliberative robots (cobots), advanced vision-based control, adaptive safety systems, online optimization and learning algorithms and connected and well-informed human operators. But it will be a huge undertaking to transform current trucks industry such that they can design, implement and maintain large scale collaborative and intelligent automation systems. This paper presents the challenges with current planning and preparation processes for final assembly as well as the requirement and possible solutions for the future processes. An industrial use case at Volvo Trucks based on Sequence Planner and ROS2 is used to evaluate the proposed planning and preparation processes.

  • 39.
    Hanna, Atieh
    et al.
    Volvo ,Gothenburg, Sweden.
    Bengtsson, K.
    Chalmers University of Technology , Göteborg, Sweden.
    Götvall, P. -L
    Volvo , Gothenburg, Sweden.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Towards safe human robot collaboration - Risk assessment of intelligent automation2020Inngår i: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA, Institute of Electrical and Electronics Engineers Inc. , 2020, s. 424-431Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Automation and robotics are two enablers for developing the Smart Factory of the Future, which is based on intelligent machines and collaboration between robots and humans. Especially in final assembly and its material handling, where traditional automation is challenging to use, collaborative robot (cobot) systems may increase the flexibility needed in future production systems. A major obstacle to deploy a truly collaborative application is to design and implement a safe and efficient interaction between humans and robot systems while maintaining industrial requirements such as cost and productivity. Advanced and intelligent control strategies is the enabler when creating this safe, yet efficient, system, but is often hard to design and build.This paper highlights and discusses the challenges in meeting safety requirements according to current safety standards, starting with the mandatory risk assessment and then applying risk reduction measures, when transforming a typical manual final assembly station into an intelligent collaborative station. An important conclusion is that current safety standards and requirements must be updated and improved and the current collaborative modes defined by the standards community should be extended with a new mode, which in this paper is refereed to the deliberative planning and acting mode.

  • 40.
    Hanna, Atieh
    et al.
    Group Trucks Operations, Sweden.
    Götvall, P. -L
    Group Trucks Operations, Sweden.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Bengtsson, K.
    Chalmers University of Technology, Göteborg, Sweden.
    Requirements for designing and controlling autonomous collaborative robots system-an industrial case2018Inngår i: Advances in Transdisciplinary Engineering, IOS Press BV , 2018, Vol. 8, s. 139-144Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Automation and Robotics have been described as two of the enabling technologies for the Industry 4.0 paradigm, especially the use of autonomous and collaborative robot systems that can work together with humans and other machines. In manual assembly for example, these so-called co-bot systems (that also includes autonomous transportation and specialized machines) can improve the automation level, product quality, as well as human working conditions. However, in order to fully benefit from co-bot systems, many challenges need to be addressed before it can be introduced in complex industries e.g. the truck industry. This paper presents a number of challenges and requirements identified during an industrial use case, where autonomous co-bot systems have been introduced into an existing manual assembly station. These requirements are related to safe and intuitive interactions, smart tools, the need to manage variability as well as the need for highly flexible communication and control. During the use case, a number of initial solutions was developed where the implemented control architecture was based on the framework Robot Operation System (ROS) and Sequence Planner (SP).

  • 41.
    Hök, Bertil
    et al.
    Hök Instrument AB, Sweden.
    Ljungblad, Jonas
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Hök Instrument AB, Sweden.
    Kaisdotter Andersson (Jonsson), Annika
    Hök Instrument AB, Sweden.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Enlund, Mats
    Västerås Sjukhus, Västerås, Sweden.
    Unobtrusive and Highly Accurate Breath Alcohol Analysis Enabled by Improved Methodology and Technology2014Inngår i: Journal of Forensic Investigation, ISSN 2330-0396, Vol. 2, nr 4, s. 1-8Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The study objective was to evaluate a novel method and technology for unobtrusive determination of breath alcohol in relation to current industrial accuracy standards. The methodology uses carbon dioxide as a tracer gas detected by sensor technology based on infrared spectroscopy. Part one of the investigation was to analyse the performance of hand-held prototype devices and included tests of resolution, unit-to-unit variation during calibration, response to alcohol containing gas pulses created with a wet gas simulator, and cross sensitivity to other substances. In part two of the study, 30 human participants provided 1465 breath tests in both unobtrusive and obtrusive use modes. The results of both parts of the study indicate that the prototype devices exceeded present industrial accuracy requirements. The proposed methodology and technology eliminate the previous contradiction between unobtrusiveness and high accuracy.

  • 42.
    Jaen Ortega, A. A.
    et al.
    Department of Mechanical Engineering Universidad Tecnologica de Panama, Panama.
    De Los Angeles Ortega Del Rosario, M.
    Department of Mechanical Engineering Universidad Tecnologica de Panama, Panama.
    Hellström, Per
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Åstrand, Elaine
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    On Understanding the Role of Exoskeleton Robots in Hand Rehabilitation: A Brief Review2022Inngår i: Proceedings - 2022 8th International Engineering, Sciences and Technology Conference, IESTEC 2022, Institute of Electrical and Electronics Engineers Inc. , 2022, s. 432-439Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Hand rehabilitation has been widely studied since it affects the life quality and independence of those affected. Hand impairment can be caused by several conditions, among them strokes and other cerebrovascular accidents, affecting the capabilities of those who survive them in performing the activities of daily living (ADL). Rehabilitation seeks to restore the ability of a person to perform these crucial ADL. There is a current trend in using robotic rehabilitation and other industry 4.0 tools since it can provide a safe, intensive, and task-oriented at a relatively low cost, which can be combined with other technologies such as virtual and augmented reality, BCI, haptics, and others. Moreover, it can provide accessibility in the face of current panoramas such as COVID-19. Hand exoskeleton robots are one of the most extended robotic devices for rehabilitation. However, a design adapted to the patient's needs is necessary to achieve their capability fully and succeed in rehabilitation. One of the main challenges is that several considerations and parameters affect these devices' design and the broad approaches that can be followed. This brief review aims to understand and empathize as a source of inspiration during the design process of hand exoskeleton robots for rehabilitation.

  • 43.
    Kaisdotter Andersson, Annika
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Hök, Bertil
    Ekström, Mikael
    Hedenstierna, Göran
    Influence from breathing pattern on alcohol and tracer gas expirograms - implications for alcolock useManuskript (preprint) (Annet vitenskapelig)
  • 44.
    Kaisdotter Andersson, Annika
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Hök, Bertil
    Hök Instrument AB.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Hedenstierna, Göran
    Uppsala University.
    Influence from breathing pattern on alcohol and tracer gas expirograms: Implications for alcolock use2011Inngår i: Forensic Science International, ISSN 0379-0738, E-ISSN 1872-6283, Vol. 206, nr 1-3, s. 52-57Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Measurement of breath alcohol concentration is strongly influenced by timing and the breathing pattern. In particular, shallow expiration and hyperventilation leads to underestimation of the breath alcohol concentration. In the present study, expirograms of alcohol, water and carbon dioxide were recorded in 30 healthy individuals at various breathing manoeuvres (tidal volume, slow maximum and vital capacity expiration, breath holding, and hyperventilation). Estimation of the end expiratory alcohol concentration with the use of simultaneously measured carbon dioxide was shown to reverse the tendency of underestimation at shallow expiration and hyperventilation. These findings indicate that breath alcohol estimations can be performed at shorter expiration time and reduced expired volume compared to existing alcolocks. This is believed to improve their usability and to prevent a possible route for manipulation.

  • 45.
    Kaisdotter Andersson, Annika
    et al.
    Hök Instrument AB och Akademin för innovation, design och teknik, School of Innovation, Design and Engineering.
    Hök, Bertil
    Rentsch, Daniel
    Ruecker, Gernot
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Improved breath alcohol analysis in patients with depressed consciousnessManuskript (preprint) (Annet vitenskapelig)
  • 46.
    Kaisdotter Andersson, Annika
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Hök, Bertil
    Hok Instrument AB, Vasteras, Sweden.
    Rentsch, Daniel
    Univ Rostock, Inst Forens Med, Rostock, Germany .
    Ruecker, Gernot
    Univ Rostock, Dept Anaesthesiol & Intens Therapy, Rostock, Germany.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Improved breath alcohol analysis in patients with depressed consciousness2010Inngår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 48, nr 11, s. 1099-1105Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Many patients in pre-hospital and emergency care are under the influence of alcohol. In addition, some of the more common pathological conditions can introduce a behaviour that can be mistaken to be related to alcohol inebriation. Fast quantitative determination of the breath alcohol concentration (BrAC) in emergency patients facilitates triage and medical assessment, but shallow expirations performed by non-cooperative patients reduce the measurement reliability. The aim of this study was to evaluate if breath alcohol analysis in non-cooperative patients can be improved with use of simultaneous measurement of the expired carbon dioxide (CO2). With prototypes of a handheld breath alcohol analyser based on infrared transmission spectroscopy the alcohol and CO2 concentration in expired breath from 37 cooperative and non-cooperative patients were measured. The results show that enhanced breath sampling with use of a pump and estimation of the end expiratory BrAC with use of the ratio between the measured partial pressure of CO2 ($$ P_{{{\text{CO}}_{2} }} $$) and a reference value of the alveolar $$ P_{{{\text{CO}}_{2} }} $$, provided adequate correlation with the blood alcohol concentration (BAC). This pre-clinical study has shown that breath alcohol analysis in shallow expirations from non-cooperative patients can be improved with use of CO2 as a tracer gas.

  • 47.
    Kaisdotter Andersson (Jonsson), Annika
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Hök, Bertil
    Hök Instrument AB.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Development of a breath alcohol analyzer for use on patients in emergency care2009Inngår i: IFMBE Proceedings, vol. 25, no. 1, 2009, s. 84-87Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The quantification of breath alcohol concentration is considered important input in medical diagnosis and triage at emergency medical care. In many severe emergency cases, for example head injuries, stroke, heart attack, diabetes, or psychological illness, the medical condition of the patient can be mistaken for alcohol intoxication. In cases like these, quantification of the alcohol concentration would facilitate and speed up the diagnostic procedure. However, the use of breath analyzers in medical care is limited as the state-of-the-art devices require active involvement of the patient, and expiratory volume and flow incompatible with patients respiratory function. This paper presents a prototype of a handheld breath analyzer based on infrared spectroscopy which does not require active involvement from the patient and also provides direct feedback on the quality of the breath test by measurement of the expired PCO2.

  • 48.
    Ljungblad, Jonas
    et al.
    Hök Instrument AB.
    Hök, Bertil
    Hök Instrument AB.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Critical Performance of a New Breath Alcohol Analyzer for Screening Applications2014Inngår i: Intelligent Sensors, Sensor Networks and Information Processing (ISSNIP), 2014 IEEE Ninth International Conference on, 2014, s. 1-4Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In screening applications there is a need forimproved breath alcohol analyzers. Accuracy, specificity,usability, and through-put are critical to the device performance. Objective: To characterize the critical performance of a newcontactless breath alcohol analyzer. Methods: The device ischaracterized by measurements using artificial breath gas andhuman subjects. Breath sampling is performed in ambient airusing carbon dioxide as a biomarker. Results: Resolution andinter-individual variation, response time, and specificity wereshown to meet the requirements of industrial standards. Thefeasibility of contactless measurement was demonstrated. Conclusions: The new device exhibits sufficient performance inmoderately diluted breath samples. Further work is underway toreach the objective of unobtrusive breath alcohol analysis.

  • 49.
    Ljungblad, Jonas
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Hök Instrument AB, Sweden.
    Hök, Bertil
    Hök Instrument AB, Sweden.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Development and Evaluation of Algorithms for Breath Alcohol Screening2016Inngår i: Sensors, E-ISSN 1424-8220, Vol. 16, nr 4, artikkel-id 469Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Breath alcohol screening is important for traffic safety, access control and other areas of health promotion. A family of sensor devices useful for these purposes is being developed and evaluated. This paper is focusing on algorithms for the determination of breath alcohol concentration in diluted breath samples using carbon dioxide to compensate for the dilution. The examined algorithms make use of signal averaging, weighting and personalization to reduce estimation errors. Evaluation has been performed by using data from a previously conducted human study. It is concluded that these features in combination will significantly reduce the random error compared to the signal averaging algorithm taken alone.

  • 50.
    Loni, Mohammad
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ahlberg, Carl
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Daneshtalab, Masoud
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Sjödin, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Embedded Acceleration of Image Classification Applications for Stereo Vision Systems2018Inngår i: Design, Automation & Test in Europe Conference & Exhibition DATE'18, 2018Konferansepaper (Annet vitenskapelig)
12 1 - 50 of 83
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf