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  • 1.
    Ahlberg, Carl
    et al.
    Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Asplund, Lars
    Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Campeanu, Gabriel
    Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ciccozzi, Federico
    Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekstrand, Fredrik
    Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Feljan, Juraj
    Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Gustavsson, Andreas
    Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Sentilles, Séverine
    Mälardalen University, School of Innovation, Design and Engineering. Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Svogor, Ivan
    FOI, University of Zagreb.
    Segerblad, Emil
    The Black Pearl: An Autonomous Underwater Vehicle2013Report (Other academic)
    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.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekstrand, Fredrik
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Spampinato, Giacomo
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Asplund, Lars
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    GIMME2 - An embedded system for stereo vision and processing of megapixel images with FPGA-acceleration2015In: 2015 International Conference on ReConFigurable Computing and FPGAs, ReConFig 2015, 2015Conference paper (Refereed)
    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.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Leon, Miguel
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekstrand, Fredrik
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Unbounded Sparse Census Transform using Genetic Algorithm2019In: 2019 IEEE WINTER CONFERENCE ON APPLICATIONS OF COMPUTER VISION (WACV), IEEE , 2019, p. 1616-1625Conference paper (Refereed)
    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.

  • 4.
    Ahlberg, Carl
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Lidholm, Jörgen
    Mälardalen University, School of Innovation, Design and Engineering.
    Ekstrand, Fredrik
    Mälardalen University, School of Innovation, Design and Engineering.
    Spampinato, Giacomo
    Mälardalen University, School of Innovation, Design and Engineering.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering.
    Asplund, Lars
    Mälardalen University, School of Innovation, Design and Engineering.
    GIMME - A General Image Multiview Manipulation Engine2011In: Proceedings of the International Conference on ReConFigurable Computing and FPGAs (ReConFig 2011), Los Alamitos, Calif: IEEE Computer Society, 2011Conference paper (Refereed)
    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.

  • 5.
    Astrand, Elaine
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Extraction of working memory load and the importance of understanding the temporal dynamics2017In: International IEEE/EMBS Conference on Neural Engineering, NER, IEEE Computer Society , 2017, p. 641-647, article id 8008433Conference paper (Refereed)
    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.

  • 6.
    Bergblomma, Marcus
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Ekström, Martin
    Mälardalen University, School of Innovation, Design and Engineering.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering.
    Gerdtman, Christer
    Motion Control AB, Västerås, Sweden .
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering.
    A wireless low latency control system for harsh environments2012In: IFAC Proceedings Volumes (IFAC-PapersOnline): Vol. 11, PART 1, 2012, p. 17-22Conference paper (Refereed)
    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.

  • 7.
    Bergblomma, Marcus
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Ekström, Martin
    Mälardalen University, School of Innovation, Design and Engineering.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering.
    Garcia Castaño, Javier
    Mälardalen University, School of Innovation, Design and Engineering.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering.
    Wireless ECG network2009In: WORLD CONGRESS ON MEDICAL PHYSICS AND BIOMEDICAL ENGINEERING, VOL 25, PT 5, 2009, p. 244-247Conference paper (Refereed)
    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.

  • 8.
    Berglin, Lena
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering.
    Monitoring health and activity by smartwear2005Conference paper (Other academic)
  • 9.
    Castano, Javier Garcia
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Andreasson, J.
    Mälardalen University, Department of Computer Science and Electronics.
    Ekström, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Wrzesniewski, H.
    Ahlbom, H.
    Bäcklund, Ylva
    Mälardalen University, Department of Computer Science and Electronics.
    Wireless industrial sensor monitoring based on BluetoothTM2003In: INDIN 2003: IEEE INTERNATIONAL CONFERENCE ON INDUSTRIAL INFORMATICS, PROCEEDINGS, 2003, p. 65-72Conference paper (Other academic)
    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.

  • 10.
    Ekstrand, Fredrik
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Ahlberg, Carl
    Mälardalen University, School of Innovation, Design and Engineering.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering.
    Asplund, Lars
    Mälardalen University, School of Innovation, Design and Engineering.
    Spampinato, Giacomo
    Mälardalen University, School of Innovation, Design and Engineering.
    Resource Limited Hardware-based Stereo Matching for High-Speed Vision System2011In: ICARA 2011 - Proceedings of the 5th International Conference on Automation, Robotics and Applications, 2011, p. 465-469Conference paper (Refereed)
    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.

  • 11.
    Ekstrand, Fredrik
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Ahlberg, Carl
    Ekström, Mikael
    Asplund, Lars
    Spampinato, Giacomo
    Utilization and Performance Considerations in Resource Optimized Stereo Matching for Real-Time Reconfigurable Hardware2012In: VISAPP 2012 - Proceedings of the International Conference on Computer Vision Theory and Application, vol. 2, 2012, p. 415-418Conference paper (Other academic)
    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.

  • 12.
    Ekstrand, Fredrik
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ahlberg, Carl
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Spampinato, Giacomo
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    High-speed segmentation-driven high-resolution matching2015In: Proceedings of SPIE - The International Society for Optical Engineering, vol. 9445, 2015, Vol. 9445, p. Article number 94451Y-Conference paper (Refereed)
    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.

  • 13.
    Ekstrand, Fredrik
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ahlberg, Carl
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Spampinato, Giacomo
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Towards an Embedded Real-Time High Resolution Vision System2014In: 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, p. 541-550Conference paper (Refereed)
    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.

  • 14.
    Ekström, Martin
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Bergblomma, Marcus
    Mälardalen University, School of Innovation, Design and Engineering.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering.
    Ekström, Mikael
    Edith Cowan University, Bunbury, Australia.
    A Bluetooth Radio Energy Consumption Model for Low Duty-Cycle Applications2012In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 61, no 3, p. 609-617Article in journal (Refereed)
    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.

  • 15.
    Ekström, Martin
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Bergblomma, Marcus
    Mälardalen University, School of Innovation, Design and Engineering.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering.
    Comparison study of ZigBee and Bluetooth with regards to power consumption, packet-error-rate and distanceManuscript (preprint) (Other academic)
    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.

  • 16.
    Ekström, Martin
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Bergblomma, Marcus
    Mälardalen University, School of Innovation, Design and Engineering.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering.
    Development of Programmable Micro Power Meter Testbed for Radio ModulesManuscript (preprint) (Other academic)
    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.

  • 17.
    Ekström, Martin
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Blom, Marcus
    Mälardalen University, School of Innovation, Design and Engineering.
    Garcia Castaño, Javier
    Mälardalen University, School of Innovation, Design and Engineering.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering.
    Bluetooth energy characteristics in wireless sensor networks2008In: 2008 3RD INTERNATIONAL SYMPOSIUM ON WIRELESS PERVASIVE COMPUTING, VOLS 1-2, 2008, p. 198-202Conference paper (Refereed)
    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.

  • 18.
    Ekström, Mikael
    et al.
    Mälardalen University, School of Innovation, Design and Engineering. 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
    Mälardalen University, School of Innovation, Design and Engineering. Stockholm University, Sweden.
    Antiferromagnetism in Zn-doped La2CuO4 as observed by muon spin resonance spectroscopy2001In: Physical Review B - Condensed Matter and Materials Physics, ISSN 0163-1829, Vol. 64, no 18, p. 1845221-1845226, article id 184522Article in journal (Refereed)
    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.

  • 19.
    Folke, Mia
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Hök, Bertil
    Hök Instrument AB, Västerås, Sweden .
    Ekström, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Bäcklund, Ylva
    Mälardalen University, Department of Computer Science and Electronics.
    End tidal carbon dioxide measurement using an electro acoustic sensor2004In: Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings, 2004, p. 3452-3455Conference paper (Other academic)
    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.

  • 20.
    Frasheri, Mirgita
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Curuklu, Baran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Analysis of perceived helpfulness in adaptive autonomous agent populations2018In: Transactions on Computational Collective Intelligence XXVIII, Springer Verlag , 2018, Vol. 10780, p. 221-252Conference paper (Refereed)
    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.

  • 21.
    Frasheri, Mirgita
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Curuklu, Baran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Comparison Between Static and Dynamic Willingness to Interact in Adaptive Autonomous Agents2018In: Proceedings of the 10th International Conference on Agents and Artificial Intelligence, 2018, Vol. 1, p. 258-267Conference paper (Refereed)
    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.

  • 22.
    Frasheri, Mirgita
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Curuklu, Baran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Papadopoulos, Alessandro
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Adaptive Autonomy in a Search and Rescue Scenario2018In: International Conference on Self-Adaptive and Self-Organizing Systems, SASO, Volume 2018-September, 15 January 2019, 2018, p. 150-155Conference paper (Refereed)
    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. 

  • 23.
    Frasheri, Mirgita
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Cürüklü, Baran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Towards Collaborative Adaptive Autonomous Agents2017In: ICAART: PROCEEDINGS OF THE 9TH INTERNATIONAL CONFERENCE ON AGENTS AND ARTIFICIAL INTELLIGENCE, VOL 1, 2017, p. 78-87Conference paper (Refereed)
    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.

  • 24.
    Frasheri, Mirgita
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Trinh, LanAnh
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Curuklu, Baran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Failure Analysis for Adaptive Autonomous Agents using Petri Nets2017In: Proceedings of the 2017 Federated Conference on Computer Science and Information Systems, FedCSIS 2017, 2017, p. 293-297Conference paper (Refereed)
    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.

  • 25.
    Hanna, A.
    et al.
    Group Trucks Operations, Sweden.
    Götvall, P. -L
    Group Trucks Operations, Sweden.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Bengtsson, K.
    Chalmers University of Technology, Göteborg, Sweden.
    Requirements for designing and controlling autonomous collaborative robots system-an industrial case2018In: Advances in Transdisciplinary Engineering, IOS Press BV , 2018, p. 139-144Conference paper (Refereed)
    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).

  • 26.
    Hök, Bertil
    et al.
    Hök Instrument AB, Sweden.
    Ljungblad, Jonas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. Hök Instrument AB, Sweden.
    Kaisdotter Andersson (Jonsson), Annika
    Hök Instrument AB, Sweden.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Enlund, Mats
    Västerås Sjukhus, Västerås, Sweden.
    Unobtrusive and Highly Accurate Breath Alcohol Analysis Enabled by Improved Methodology and Technology2014In: Journal of Forensic Investigation, ISSN 2330-0396, Vol. 2, no 4, p. 1-8Article in journal (Refereed)
    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.

  • 27.
    Kaisdotter Andersson, Annika
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Hök, Bertil
    Ekström, Mikael
    Hedenstierna, Göran
    Influence from breathing pattern on alcohol and tracer gas expirograms - implications for alcolock useManuscript (preprint) (Other academic)
  • 28.
    Kaisdotter Andersson, Annika
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Hök, Bertil
    Hök Instrument AB.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering.
    Hedenstierna, Göran
    Uppsala University.
    Influence from breathing pattern on alcohol and tracer gas expirograms: Implications for alcolock use2011In: Forensic Science International, ISSN 0379-0738, E-ISSN 1872-6283, Vol. 206, no 1-3, p. 52-57Article in journal (Refereed)
    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.

  • 29.
    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
    Mälardalen University, School of Innovation, Design and Engineering.
    Improved breath alcohol analysis in patients with depressed consciousnessManuscript (preprint) (Other academic)
  • 30.
    Kaisdotter Andersson, Annika
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    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
    Mälardalen University, School of Innovation, Design and Engineering.
    Improved breath alcohol analysis in patients with depressed consciousness2010In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 48, no 11, p. 1099-1105Article in journal (Refereed)
    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.

  • 31.
    Kaisdotter Andersson (Jonsson), Annika
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Hök, Bertil
    Hök Instrument AB.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering.
    Development of a breath alcohol analyzer for use on patients in emergency care2009In: IFMBE Proceedings, vol. 25, no. 1, 2009, p. 84-87Conference paper (Refereed)
    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.

  • 32.
    Ljungblad, Jonas
    et al.
    Hök Instrument AB.
    Hök, Bertil
    Hök Instrument AB.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Critical Performance of a New Breath Alcohol Analyzer for Screening Applications2014In: Intelligent Sensors, Sensor Networks and Information Processing (ISSNIP), 2014 IEEE Ninth International Conference on, 2014, p. 1-4Conference paper (Refereed)
    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.

  • 33.
    Ljungblad, Jonas
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. Hök Instrument AB, Sweden.
    Hök, Bertil
    Hök Instrument AB, Sweden.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Development and Evaluation of Algorithms for Breath Alcohol Screening2016In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 16, no 4, article id 469Article in journal (Refereed)
    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.

  • 34.
    Loni, Mohammad
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ahlberg, Carl
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Daneshtalab, Masoud
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Sjödin, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Embedded Acceleration of Image Classification Applications for Stereo Vision Systems2018In: Design, Automation & Test in Europe Conference & Exhibition DATE'18, 2018Conference paper (Other academic)
  • 35.
    Lönnblad, Jens
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Castano, J.G
    Mälardalen University, Department of Computer Science and Electronics.
    Ekström, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Lindén, Maria
    Mälardalen University, Department of Computer Science and Electronics.
    Bäcklund, Ylva
    Mälardalen University, Department of Computer Science and Electronics.
    Optimization of wireless Bluetooth2004In: Annual International Conference of the IEEE Engineering in Medicine and Biology - ProceedingsVolume 26 III, 2004, p. 2133-2136Conference paper (Other academic)
    Abstract [en]

    Within this study, three different Bluetooth™ sensor systems, replacing cables for transmission of biomedical sensor data, have been designed and evaluated. The three sensor architectures are built on 1-, 2- and 3-chip solutions and depending on the monitoring situation and signal character, different solutions are optimal. Essential parameters for all systems have been low physical weight and small size, resistance to interference and interoperability with other technologies as global- or local networks, PC's and mobile phones. Two different biomedical input signals, ECG and PPG (photoplethysmography), have been used to evaluate the three solutions. The study shows that it is possibly to continuously transmit an analogue signal. At low sampling rates and slowly varying parameters, as monitoring the heart rate with PPG, the 1-chip solution is the most suitable, offering low power consumption and thus a longer battery lifetime or a smaller battery, minimizing the weight of the sensor system. On the other hand, when a higher sampling rate is required, as an ECG, the 3-chip architecture, with a FPGA or micro-controller, offers the best solution and performance. Our conclusion is that Bluetooth™ might be useful in replacing cables of medical monitoring systems.

  • 36.
    Miloradovic, Branko
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Çürüklü, Baran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    A genetic mission planner for solving temporal multi-agent problems with concurrent tasks2017In: Lecture Notes in Computer Science, vol. 10386, Springer Verlag , 2017, p. 481-493Conference paper (Refereed)
    Abstract [en]

    In this paper, a centralized mission planner is presented. The planner employs a genetic algorithm for the optimization of the temporal planning problem. With the knowledge of agents’ specification and capabilities, as well as constraints and parameters for each task, the planner can produce plans that utilize multi-agent tasks, concurrency on agent level, and heterogeneous agents. Numerous optimization criteria that can be of use to the mission operator are tested on the same mission data set. Promising results and effectiveness of this approach are presented in the case study section. 

  • 37.
    Miloradovic, Branko
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Çürüklü, Baran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    A genetic planner for mission planning of cooperative agents in an underwater environment2016In: The 2016 IEEE Symposium Series on Computational Intelligence SSCI'16, 2016, article id 7850163Conference paper (Refereed)
    Abstract [en]

    In this paper, a Genetic Algorithm (GA) is used for solving underwater mission planning problem. The proposed genetic planner is capable of utilizing multiple Autonomous Underwater Vehicles (AUVs) and Remotely Operated Vehicles (ROVs) in a mission plan, as well as running multiple tasks in parallel on the agent’s level. The problem is described using STRIPS modeling language. The proposed planner shows high robustness regarding initial population set, which is randomly generated. Chromosomes have variable length, consisting of active and inactive genes. Various genetic operators are used in order to improve convergence of the algorithm. Although genetic planner presented in this work is for underwater missions, this planning approach is universal, and it is not domain dependent. Results for a realistic case study with five AUVs and almost 30 tasks show that this approach can be used successfully for solving complex mission planning problems.

  • 38.
    Miloradović, Branko
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Curuklu, Baran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Papadopoulos, Alessandro
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Extended colored traveling salesperson for modeling multi-agent mission planning problems2019In: ICORES 2019 - Proceedings of the 8th International Conference on Operations Research and Enterprise Systems, SciTePress , 2019, p. 237-244Conference paper (Refereed)
    Abstract [en]

    In recent years, multi-agent systems have been widely used in different missions, ranging from underwater to airborne. A mission typically involves a large number of agents and tasks, making it very hard for the human operator to create a good plan. A search for an optimal plan may take too long, and it is hard to make a time estimate of when the planner will finish. A Genetic algorithm based planner is proposed in order to overcome this issue. The contribution of this paper is threefold. First, an Integer Linear Programming (ILP) formulation of a novel Extensive Colored Traveling Salesperson Problem (ECTSP) is given. Second, a new objective function suitable for multi-agent mission planning problems is proposed. Finally, a reparation algorithm to allow usage of common variation operators for ECTSP has been developed. 

  • 39.
    Spampinato, Giacomo
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Lidholm, Jörgen
    Mälardalen University, School of Innovation, Design and Engineering.
    Ahlberg, Carl
    Mälardalen University, School of Innovation, Design and Engineering.
    Ekstrand, Fredrik
    Mälardalen University, School of Innovation, Design and Engineering.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering.
    Asplund, Lars
    Mälardalen University, School of Innovation, Design and Engineering.
    An Embedded Stereo Vision Module for 6D Pose Estimation and Mapping2011In: Proceedings of the IEEE international conference on Intelligent Robots and Systems IROS2011, New York: IEEE Press, 2011, p. 1626-1631Conference paper (Refereed)
    Abstract [en]

    This paper presents an embedded vision system based on reconfigurable hardware (FPGA) and two CMOS cameras to perform stereo image processing and 3D mapping for autonomous navigation. We propose an EKF based visual SLAM and sparse feature detectors to achieve 6D localization of the vehicle in non flat scenarios. The system can operate regardless of the odometry information from the vehicle since visual odometry is used. As a result, the final system is compact and easy to install and configure.

  • 40.
    Spampinato, Giacomo
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lidholm, Jörgen
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ahlberg, Carl
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekstrand, Fredrik
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering.
    Asplund, Lars
    An embedded stereo vision module for industrial vehicles automation2013In: Proceedings of the IEEE International Conference on Industrial Technology, IEEE , 2013, p. 52-57Conference paper (Refereed)
    Abstract [en]

    This paper presents an embedded vision system based on reconfigurable hardware (FPGA) to perform stereo image processing and 3D mapping of sparse features for autonomous navigation and obstacle detection in industrial settings. We propose an EKF based visual SLAM to achieve a 6D localization of the vehicle even in non flat scenarios. The system uses vision as the only source of information. As a consequence, it operates regardless of the odometry from the vehicle since visual odometry is used. © 2013 IEEE.

  • 41.
    Spampinato, Giacomo
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Lidholm, Jörgen
    Mälardalen University, School of Innovation, Design and Engineering.
    Ekstrand, Fredrik
    Mälardalen University, School of Innovation, Design and Engineering.
    Ahlberg, Carl
    Mälardalen University, School of Innovation, Design and Engineering.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering.
    Asplund, Lars
    Mälardalen University, School of Innovation, Design and Engineering.
    Navigation in a box: Stereovision for industry automation2010In: Advances in Theory and Applications of Stereo Vision / [ed] Asim Bhatti, InTech , 2010Chapter in book (Other academic)
    Abstract [en]

    The research presented addresses the emerging topic of AGVs (Automated Guided Vehicles) specifically related to industrial sites. The work presented has been carried out in the frame of the MALTA project (Multiple Autonomous forklifts for Loading and Transportation Applications), a joint research project between industry and university, funded by the European Regional Development and Robotdalen, in partnership with theSwedish Knowledge Foundation. The project objective is to create fully autonomous forklift trucks for paper reel handling. The result is expected to be of general benefit for industries that use forklift trucks in their material handling through higher operating efficiency and better flexibility with reduced risk for accidents and handling damages than if only manual forklift trucks are used. A brief overview of the state of the art in AGVs will be reported in order to better understand the new challenges and technologies. Among the emerging technologies used for vehicle automation, vision is one of the most promising in terms of versatility and efficiency, with a high potential to drastically reduce the costs.

  • 42.
    Trinh, Lan Anh
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Cürüklü, Baran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Fault Tolerance Analysis for Dependable Autonomous Agents Using Colored Time Petri Nets2017In: ICAART: PROCEEDINGS OF THE 9TH INTERNATIONAL CONFERENCE ON AGENTS AND ARTIFICIAL INTELLIGENCE, VOL 1, 2017, p. 228-235Conference paper (Refereed)
    Abstract [en]

    Fault tolerance has become more and more important in the development of autonomous systems with the aim to help the system to recover its normal activities even when some failures happen. Yet, one of the concerns is how to analyze the reliability of a fault tolerance mechanism with regards to the collaboration of multiple agents to complete a complicated task. To do so, an approach of fault tolerance analysis with the colored time Petri net framework is proposed in this work, where a task can be represented by a tree of different concurrent and dependent subtasks to assign to agents. Different subtasks and agents are modeled by color tokens in Petri network. The time values are added to evaluate the processing performance of the whole system with respect to its ability to solve a task with fault tolerance ability. The colored time Petri nets are then tested with simulation of centralized and distributed systems. Finally the experiments are performed to show the feasibility of the proposed approach. From the basics of this study, a generalized framework in the future can be developed to address the fault tolerance analysis for a set of agents working with a sophisticated plan to achieve a common target.

  • 43.
    Trinh, Lan Anh
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Curuklu, Baran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Petri Net Based Navigation Planning with Dipole Field and Dynamic Window Approach for Collision Avoidance2019In: International Conference on Control, Decision and Information Technologies CoDIT, 2019, p. 1013-1018, article id 8820359Conference paper (Refereed)
    Abstract [en]

    This paper presents a novel path planning system for multiple robots working in an uncontrolled environment in the presence of humans. The approach combines the use of Petri net to plan the movement of multiple robots to prevent the risk of congestion caused by routing several robots into a narrow region, together with a dipole field with dynamic window approach to avoid collisions of a robot with dynamic obstacles. By regarding the velocity and direction of both humans and robots as a source of magnetic dipole moment, the dipole-dipole interaction between the moving objects will generate repulsive forces to prevent collisions. The whole system is presented on robot operating system platform so that its implementation can be extendable into real robots. Experimental results with Gazebo simulator demonstrates the effectiveness of the proposed approach.

  • 44.
    Trinh, LanAnh
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Curuklu, Baran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Dependability for Autonomous Control with a Probability Approach2017In: ERCIM News, ISSN 0926-4981, E-ISSN 1564-0094, no 109, p. 22-23Article in journal (Refereed)
    Abstract [en]

    For the last decade, dependability - the ability to offer a service that can be trusted - has been the focus of much research, and is of particular interest when designing and building systems. We are developing a dependable framework for an autonomous system and its control.

  • 45.
    Trinh, LanAnh
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Curuklu, Baran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Dipole Flow Field for Dependable Path Planning of Multiple Agents2017In: IEEE/RSJ International Conference on Intelligent Robots and Systems IROS, 2017Conference paper (Refereed)
  • 46.
    Trinh, LanAnh
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ekström, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Curuklu, Baran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Toward Shared Working Space of Human and Robotic Agents Through Dipole Flow Field for Dependable Path Planning2018In: Frontiers in Neurorobotics, ISSN 1662-5218, Vol. 12, article id 28Article in journal (Refereed)
    Abstract [en]

    Recent industrial developments in autonomous systems, or agents, which assume that humans and the agents share the same space or even work in close proximity, open for new challenges in robotics, especially in motion planning and control. In these settings, the control system should be able to provide these agents a reliable path following control when they are working in a group or in collaboration with one or several humans in complex and dynamic environments. In such scenarios, these agents are not only moving to reach their goals, i.e., locations, they are also aware of the movements of other entities to find a collision-free path. Thus, this paper proposes a dependable, i.e, safe, reliable and effective, path planning algorithm for a group of agents that share their working space with humans. Firstly, the method employs the Theta* algorithm to initialize the paths from a starting point to a goal for a set of agents. As Theta* algorithm is computationally heavy, it only reruns when there is a significant change of the environment. To deal with the movements of the agents, a static flow field along the configured path is defined. This field is used by the agents to navigate and reach their goals even if the planned trajectories are changed. Secondly, a dipole field is calculated to avoid the collision of agents with other agents and human subjects. In this approach, each agent is assumed to be a source of a magnetic dipole field in which the magnetic moment is aligned with the moving direction of the agent. The magnetic dipole-dipole interactions between these agents generate repulsive forces to help them to avoid collision. The effectiveness of the proposed approach has been evaluated with extensive simulations. The results show that the static flow field is able to drive agents to the goals with a small number of requirements to update the path of agents. Meanwhile, the dipole flow field plays an important role to prevent collisions. The combination of these two fields results in a safe path planning algorithm, with a deterministic outcome, to navigate agents to their desired goals.

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