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  • 1.
    Abdul Waheed, Malik
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Cheng, Xin
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Imran, Muhammad
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Kjeldsberg, Per Gunnar
    NTNU.
    Generalized Architecture for a Real-time Computation of an Image Component Features on a FPGAManuscript (preprint) (Other academic)
    Abstract [en]

    This paper describes a generalized architecture for real-time component labeling and computation of image component features. Computing real-time image component features is one of the most important paradigms for modern machine vision systems. Embedded machine vision systems demand robust performance, power efficiency as well as minimum area utilization. The presented architecture can easily be extended with additional modules for parallel computation of arbitrary image component features. Hardware modules for component labeling and feature calculation run in parallel. This modularization makes the architecture suitable for design automation. Our architecture is capable of processing 390 video frames per second of size 640x480 pixels. Dynamic power consumption is 24.20mW at 86 frames per second on a Xilinx Spartran6 FPGA.

  • 2.
    Alqaysi, Hiba
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Fedorov, Igor
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Design Exploration of Multi-Camera Dome2019In: ICDSC 2019 Proceedings of the 13th International Conference on Distributed Smart Cameras, New York, NY: ACM Digital Library, 2019, article id Article No. 7aConference paper (Refereed)
    Abstract [en]

    Visual monitoring systems employ distributed smart cameras toeffectively cover a given area satisfying specific objectives. Thechoice of camera sensors and lenses and their deployment affectsdesign cost, accuracy of the monitoring system and the ability toposition objects within the monitored area. Design cost can bereduced by investigating deployment topology such as groupingcameras together to form a dome at a node and optimize it formonitoring constraints. The constraints may include coverage area,number of cameras that can be integrated in a node and pixelresolution at a given distance. This paper presents a method foroptimizing the design cost of multi-camera dome by analyzing tradeoffsbetween monitoring constraints. The proposed method can beused to reduce monitoring cost while fulfilling design objectives.Results show how to increase coverage area for a given cost byrelaxing requirements on design constraints. Multi-camera domescan be used in sky monitoring applications such as monitoring windparks and remote air-traffic control of airports where all-round fieldof view about a point is required to monitor.

  • 3.
    Amir, Yousaf Muhammad
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    High Precision Laser Scanning of Metallic Surfaces2017In: International Journal of Optics, ISSN 1687-9384, E-ISSN 1687-9392, article id 4134205Article in journal (Refereed)
    Abstract [en]

    Speckle noise, dynamic range of light intensity, and spurious reflections are major challenges when laser scanners are used for 3D surface acquisition. In this work, a series of image processing operations, that is, Spatial Compound Imaging, High Dynamic Range Extension, Gray Level Transformation, and Most Similar Nearest Neighbor are proposed to overcome the challenges coming from the target surface. A prototype scanner for metallic surfaces is designed to explore combinations of these image processing operations. The main goal is to find the combination of operations thatwill lead to the highest possible robustness andmeasurement precision at the lowest possible computational load. Inspection of metallic tools where the surface of its edge must be measured at micrometer precision is our test case. Precision of heights measured without using the proposed image processing is firstly analyzed to be +/- 7.6 mu m at 68% confidence level. The best achieved height precision was +/- 4.2 mu m. This improvement comes at 24 times longer processing time and five times longer scanning time. Dynamic range extension of the image capture improves robustness since the numbers of saturated or underexposed pixels are substantially reduced. Using a high dynamic range (HDR) camera offers a compromise between processing time, robustness, and precision.

  • 4.
    Anwar, Qaiser
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Malik, Abdul Waheed
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Design of coded reference labels for indoor optical navigation using monocular camera2013In: 2013 International Conference on Indoor Positioning and Indoor Navigation, IPIN 2013, IEEE Computer Society, 2013, p. Art. no. 6817925-Conference paper (Refereed)
    Abstract [en]

    We present a machine vision based indoor navigation system. The paper describes a pose estimation of machine vision system by recognizing rotationally independent optimized color reference labels combined with a geometrical camera calibration model, which determines a set of camera parameters. A reference label carries one byte of information, which can be uniquely designed for various values. More than four reference labels are used in the image to calculate the localization coordinates of the system. An algorithm in Matlab has been developed so that a machine vision system can recognize N number of labels at any given orientation. In addition, a one channel color technique is applied in segmentation process, due to this technique the number of segmented image components is reduced significantly, limiting the memory storage requirement and processing time. The algorithm for pose estimation is based on direct linear transformation (DLT) method with a set of control reference labels in relation to the camera calibration model. From the experiments we concluded that the pose of the machine vision system can be calculated with relatively high precision, in the calibrated environment of reference labels. © 2013 IEEE.

  • 5.
    Cheng, Xin
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Abdul Waheed, Malik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Color Symbol Design and Its Classification for Optical NavigationManuscript (preprint) (Other academic)
    Abstract [en]

    We explored the color symbol design and its recognition in image as reference structure for optical navigation. A colors pair was first determined as foreground and background from HSI color palette and then a color symbol was designed as reference structure. The advantage of using this selected color symbol is a significant reduction, up to 97%, of segmented image components as compared to the grey scale image used. The reduction of segmented components in image will result in saving the hardware resources e.g. memory and processing power which are very important constraint for embedded platforms. A color symbol pattern was designed, comprising of three concentric circles with selected color pair. Inside the inner most circle is the Area Of Interest (AOI), the contents of AOI depends on the particular application. A hardware centric image analysis algorithm is developed for easy and robust recognition. Image components are identified after preprocessing, segmentation and labeling. The color symbol can be recognized at a classification step. Evaluating a variety of viewing angles and reading distances ranging from 30 to 150 degrees and from 1 to 10 meters gives a classification success rate of 72 percent of the positions.

  • 6.
    Cheng, Xin
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Abdul Waheed, Malik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Optimized Color Pair Selection for Label Design2011In: Proceedings Elmar - International Symposium Electronics in Marine, Zadar, Croatia: IEEE conference proceedings, 2011, p. 115-118Conference paper (Refereed)
    Abstract [en]

    We present in this paper a technique for designing reference labels that can be used for optical navigation. We optimize the selection of foreground and background colors used for the printed reference labels. This optimization calibrates for individual color responses among printers and cameras such that the Signal to Noise Ratio (SNR) is maximized. Experiments show that we get slightly smaller SNR for the color labels compared to using a monochrome technique. However, the number of segmented image components is reduced significantly by as much as 78 percent. This reduction of number of image components will in turn reduce the memory storage requirement for the computing embedded system.

  • 7.
    Cheng, Xin
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Malik, Waheed
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Hardware centric machine vision for high precision center of gravity calculation2010In: World Academy of Science, Engineering and Technology: An International Journal of Science, Engineering and Technology, ISSN 2010-376X, E-ISSN 2070-3740, Vol. 40, p. 576-583Article in journal (Refereed)
    Abstract [en]

    We present a hardware oriented method for real-time measurements of object's position in video. The targeted application area is light spots used as references for robotic navigation. Different algorithms for dynamic thresholding are explored in combination with component labeling and Center Of Gravity (COG) for highest possible precision versus Signal-to-Noise Ratio (SNR). This method was developed with a low hardware cost in focus having only one convolution operation required for preprocessing of data.

  • 8.
    Cheng, Xin
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Malik, Waheed
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Hardware Centric Machine Vision for High Precision Center of Gravity Calculation2010In: PROCEEDINGS OF WORLD ACADEMY OF SCIENCE, ENGINEERING AND TECHNOLOGY, 2010, p. 736-743Conference paper (Refereed)
    Abstract [en]

    We present a hardware oriented method for real-time measurements of object’s position in video. The targeted application area is light spots used as references for robotic navigation. Different algorithms for dynamic thresholding are explored in combination with component labeling and Center Of Gravity (COG) for highest possible precision versus Signal-to-Noise Ratio (SNR). This method was developed with a low hardware cost in focus having only one convolution operation required for preprocessing of data.

  • 9.
    Fedorov, Igor
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Alqaysi, Hiba
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Towards calibration of outdoor multi-camera visual monitoring system2018In: ACM International Conference Proceeding Series, New York, NY, US: ACM Digital Library, 2018, , p. 6Conference paper (Refereed)
    Abstract [en]

    This paper proposes a method for calibrating of multi-camera systems where no natural reference points exist in the surrounding environment. Monitoring the air space at wind farms is our test case. The goal is to monitor the trajectories of flying birds to prevent them from colliding with rotor blades. Our camera calibration method is based on the observation of a portable artificial reference marker made out of a pulsed light source and a navigation satellite sensor module. The reference marker can determine and communicate its position in the world coordinate system at centimeter precision using navigartion sensors. Our results showed that simultaneous detection of the same marker in several cameras having overlapping field of views allowed us to determine the markers position in 3D world coordinate space with an accuracy of 3-4 cm. These experiments were made in the volume around a wind turbine at distances from cameras to marker within a range of 70 to 90 m.

  • 10.
    Hashemi, Ashkan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Hardware Centric Automatic Recognition of Road Signs2012In: ISCAIE 2012 - 2012 IEEE Symposium on Computer Applications and Industrial Electronics, IEEE conference proceedings, 2012, p. 157-162Conference paper (Refereed)
    Abstract [en]

    In this paper we present a novel and robust algorithm for automatic recognition of road signs by using histogram of oriented gradient (HOG) as the main feature and minimum distance classifier (MDC) to classify numbers written on speed limit road signs. It also describes how other geometrical properties can be added to feature vector in order to increase the robustness of proposed algorithm.

  • 11.
    Imran, Muhammad
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Khursheed, Khursheed
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Malik, Abdul Waheed
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Ahmad, Naeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Architecture Exploration Based on Tasks Partitioning Between Hardware, Software and Locality for a Wireless Vision Sensor Node2012In: International Journal of Distributed Systems and Technologies, ISSN 1947-3532, E-ISSN 1947-3540, Vol. 3, no 2, p. 58-71Article in journal (Refereed)
    Abstract [en]

    Wireless Vision Sensor Networks (WVSNs) is an emerging field which consists of a number of Visual Sensor Nodes (VSNs). Compared to traditional sensor networks, WVSNs operates on two dimensional data, which requires high bandwidth and high energy consumption. In order to minimize the energy consumption, the focus is on finding energy efficient and programmable architectures for the VSN by partitioning the vision tasks among hardware (FPGA), software (Micro-controller) and locality (sensor node or server). The energy consumption, cost and design time of different processing strategies is analyzed for the implementation of VSN. Moreover, the processing energy and communication energy consumption of VSN is investigated in order to maximize the lifetime. Results show that by introducing a reconfigurable platform such as FPGA with small static power consumption and by transmitting the compressed images after pixel based tasks from the VSN results in longer battery lifetime for the VSN.

  • 12.
    Imran, Muhammad
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Munir, Huma
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Low complexity FPGA based background subtraction technique for thermal imagery2015In: ACM International Conference Proceeding Series, Association for Computing Machinery (ACM), 2015, p. 1-6Conference paper (Refereed)
    Abstract [en]

    Embedded smart camera systems are gaining popularity for a number of real world surveillance applications. However, there are still challenges, i.e. variation in illumination, shadows, occlusion, and weather conditions while employing the vision algorithms in outdoor environments. For safety-critical surveillance applications, the visual sensors can be complemented with beyond-visual-range sensors. This in turn requires analysis, development and modification of existing imaging techniques. In this work, a low complexity background modelling and subtraction technique has been proposed for thermal imagery. The proposed technique has been implemented on Field Programmable Gate Arrays (FPGAs) after in-depth analysis of different sets of images, characterizing poor signal-to-noise ratio challenges, e.g. motion of high frequency background objects, temperature variation and camera jitter etc. The proposed technique dynamically updates the background on pixel level and requires a single frame storage as opposed to existing techniques. The comparison of this approach with two other approaches show that this approach performs better in different environmental conditions. The proposed technique has been modelled in Register Transfer Logic (RTL) and implementation on the latest FPGAs shows that the design requires less than 1 percent logics, 47 percent block RAMs, and consumes 91 mW power consumption on Artix-7 100T FPGA.

  • 13.
    Jonsson, Patrik
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Casselgren, Johan
    Division of Experimental Mechanics, Luleå University of Technology, Luleå, Sweden .
    Road surface status classification using spectral analysis of NIR camera images2015In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 15, no 3, p. 1641-1656Article in journal (Refereed)
    Abstract [en]

    There is a need for an automated road status classification system considering the vast number of weather-related accidents that occur every winter. Previous research has shown that it is possible to detect hazardous road conditions, including, for example, icy pavements, using single point infrared illumination and infrared detectors. In this paper, we extend this research into camera surveillance of a road section allowing for classification of area segments of weather-related road surface conditions such as wet, snow covered, or icy. Infrared images have been obtained using an infrared camera equipped with a set of optical wavelength filters. The images have primarily been used to develop multivariate data models and also for the classification of road conditions in each pixel. This system is a vast improvement on existing single spot road status classification systems. The resulting imaging system can reliably distinguish between dry, wet, icy, or snow covered sections on road surfaces.

  • 14.
    Jonsson, Patrik
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Dobslaw, Felix
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Computer and System science.
    Vaa, Torgeir
    Road Condition Imaging: Model Development2015Conference paper (Refereed)
    Abstract [en]

    It is important to classify road conditions to plan winter road maintenance, carry out proper actions and issue warnings to road users. Existing sensor systems only cover parts of the road surface and manual observations can vary depending on those who classify the observations. One challenge is to classify road conditions with automatic monitoring systems. This paper presents a model based on data from winter 2013-2014, retrieved from two installations in Sweden and Norway. To address that challenge an innovative and cost effective road condition imaging system, capable of classifying individual pixels of an image as dry, wet, icy or snowy, is evaluated. The system uses a near infra-red image detector and optical wavelength filters. By combining data from images taken from different wavelength filters it is possible to determine the road status by using multiclass classifiers. One classifier for each road condition was developed, which implies that a pixel can be classified to two or more road conditions at the same time. This multiclass problem is solved by developing a Bayesian Network that uses road weather information system data for the calculation of the probabilities for different road conditions.

  • 15.
    Jonsson, Patrik
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Vaa, Torgeir
    Bogren, Jörgen
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Road Condition Imaging - Case StudyManuscript (preprint) (Other academic)
    Abstract [en]

    It is often a problem to get descriptive road status information from the automatic road weather information systems. These monitoring stations are normally equipped with meteorological sensors and road temperature sensors. Even though some monitoring stations have road status sensors and cameras, it is difficult to assess the current road condition. The problem is that the road status sensors cover only a small part of the road’s width and length and camera images are time consuming and difficult to manually evaluate. In this paper, a new automatic road status camera that gives an image of the road status and that covers a whole lane is evaluated. This means that differences the road surface within and outside of wheel tracks can be examined. Hazardous situations with wet wheel tracks and ice in-between the tracks can be detected and road users can be warned until appropriate maintenance have been performed. This new infra-red road status camera was evaluated on data retrieved during winter 2013-2014, and it was found that road conditions differ considerably during the winter, and that differences in and between the wheel tracks occur. A correlation of friction data retrieved by vehicle mounted slip wheels with this new road condition imaging system was completed. The findings indicate that slip friction measurements correlate well with the classified road conditions from the infra-red imaging system.

  • 16.
    Khursheed, Khursheed
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Imran, Muhammad
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Malik, Abdul Waheed
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Exploration of tasks partitioning between hardware software and locality for a wireless camera based vision sensor node2011In: Proceedings - 6th International Symposium on Parallel Computing in Electrical Engineering, PARELEC 2011, IEEE conference proceedings, 2011, p. 127-132Conference paper (Refereed)
    Abstract [en]

    In this paper we have explored different possibilities for partitioning the tasks between hardware, software and locality for the implementation of the vision sensor node, used in wireless vision sensor network. Wireless vision sensor network is an emerging field which combines image sensor, on board computation and communication links. Compared to the traditional wireless sensor networks which operate on one dimensional data, wireless vision sensor networks operate on two dimensional data which requires higher processing power and communication bandwidth. The research focus within the field of wireless vision sensor networks have been on two different assumptions involving either sending raw data to the central base station without local processing or conducting all processing locally at the sensor node and transmitting only the final results. Our research work focus on determining an optimal point of hardware/software partitioning as well as partitioning between local and central processing, based on minimum energy consumption for vision processing operation. The lifetime of the vision sensor node is predicted by evaluating the energy requirement of the embedded platform with a combination of FPGA and micro controller for the implementation of the vision sensor node. Our results show that sending compressed images after pixel based tasks will result in a longer battery life time with reasonable hardware cost for the vision sensor node. © 2011 IEEE.

  • 17.
    Lawal, Najeem
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    O´Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    C++ based System Synthesis of Real-Time Video Processing Systems targeting FPGA Implementation2007In: Proceedings - 21st International Parallel and Distributed Processing Symposium, IPDPS 2007; Abstracts and CD-ROM, Long Beach, CA: IEEE conference proceedings, 2007, p. 1-7, article id 4228121Conference paper (Refereed)
    Abstract [en]

    Implementing real-time video processing systems put high requirements on computation and memory performance. FPGAs have proven to be effective implementation architecture for these systems. However, the hardware based design flow for FPGAs make the implementation task complex. The system synthesis tool presented in this paper reduces this design complexity. The synthesis is done from a SystemC based coarse grain dataflow graph that captures the video processing system. The data flow graph is optimized and mapped onto an FPGA. The results from real-life video processing systems clearly show that the presented tool produces effective implementations.

  • 18.
    Lawal, Najeem
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    C++ based System Synthesis of Real-Time Video Processing Systems targeting FPGA Implementation2006In: Proceedings of the FPGA World Conference 2006, 2006Conference paper (Refereed)
    Abstract [en]

    Implementing real-time video processing systems put high requirements on computation and memory performance. FPGAs have shown to be an effective implementation architecture for these systems. However, the hardware based design flow for FPGAs make the implementation task complex. The system synthesis tool presented in this paper reduces this design complexity. The synthesis is done from a SystemC based coarse grain data flow graph that captures the video processing system. The data flow graph is optimized and mapped onto an FPGA. The results from real-life video processing systems clearly show that the presented tool produces effective implementations.

  • 19.
    Lawal, Najeem
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Address Generation for FPGA RAMs for Efficient Implementation of Real-Time Video Processing Systems2005In: Proceedings - 2005 International Conference on Field Programmable Logic and Applications, FPL, IEEE conference proceedings, 2005, p. 136-141, article id 1515712Conference paper (Refereed)
    Abstract [en]

    FPGA offers the potential of being a reliable, and high-performance reconfigurable platform for the implementation of real-time video processing systems. To utilize the full processing power of FPGA for video processing applications, optimization of memory accesses and the implementation of memory architecture are important issues. This paper presents two approaches, base pointer approach and distributed pointer approach, to implement accesses to on-chip FPGA Block RAMs. A comparison of the experimental results obtained using the two approaches on realistic image processing systems design cases is presented. The results show that compared to the base pointer approach the distributed pointer approach increases the potential processing power of FPGA, as a reconfigurable platform for video processing systems.

  • 20.
    Lawal, Najeem
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    O´Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Architecture driven memory allocation for FPGA Based Real-Time Video Processing Systems2011In: Proceedings of the 2011 7th Southern Conference on Programmable Logic, SPL 2011 2011, Article number 5782639, IEEE conference proceedings, 2011, p. 143-148Conference paper (Refereed)
    Abstract [en]

    In this paper, we present an approach that uses information about the FPGA architecture to achieve optimized allocation of embedded memory in real-time video processing system. A cost function defined in terms of required memory sizes, available block- and distributed-RAM resources is used to motivate the allocation decision. This work is a high-level exploration that generates VHDL RTL modules and synthesis constraint files to specify memory allocation. Results show that the proposed approach achieves appreciable reduction in block RAM usage over previous logic to memory mapping approach at negligible increase in logic usage

  • 21.
    Lawal, Najeem
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Power-aware automatic constraint generation for FPGA based real-time video processing systems2007In: 25th Norchip Conference, NORCHIP, New York: IEEE conference proceedings, 2007, p. 124-128Conference paper (Refereed)
    Abstract [en]

    The introduction of embedded DSP blocks and embedded memory has made FPGAs an attractive architecture for implementation of real-time video processing systems. The big bottle neck of the FPGA compared to other programmable architectures is the complex programming model. This paper presents an automatic generation of placement and routing constraints for FPGA implementation of real-time video processing systems as one step to automate the programming model. The constraint generator targets lower power consumption, better resource utilization and reduced development time. Results show that a 28 % reduction in dynamic power can be achieved using the proposed approach over traditional logic to memory mapping.

  • 22.
    Lawal, Najeem
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Norell, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Ram allocation algorithm for video processing applications on FPGA2006In: Journal of Circuits, Systems and Computers, ISSN 0218-1266, Vol. 15, no 5, p. 679-699Article in journal (Refereed)
    Abstract [en]

    This paper presents an algorithm for the allocation of on-chip FPGA Block RAMs for the implementation of Real-Time Video Processing Systems. The effectiveness of the algorithm is shown through the implementation of realistic image processing systems. The algorithm, which is based on a heuristic, seeks the most cost-effective way of allocating memory objects to the FPGA Block RAMs. The experimental results obtained, show that this algorithm generates results which are close to the theoretical optimum for most design cases.

  • 23.
    Lepistö, Niklas
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    O'Nils, Mattias
    Design Exploration of Video Pre-Processor for FPGA based SoC2006In: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), Berlin: Springer Verlag , 2006, Vol. 3985, p. 87-92Conference paper (Refereed)
    Abstract [en]

    FPGA based implementation of embedded systems has many attractive characteristics such as: flexibility, low cost, high integration, embedded distributed memories and extensive parallelism. One application where there is a significant possible potential for FPGA is for the implementation of real-time video processing. In this paper we present an analysis of a video pre-processor and how this affects the FPGA and RAM resource usage and performance. From these results we indicate the best space-time mapping of operations under different design constraints. These results can be used as a decision base when implementing an FPGA based video enabled display unit.

  • 24.
    Lepistö, Niklas
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    High Performance FPGA based Camera Architecture for Range Imaging2005In: 23rd NORCHIP Conference 2005, IEEE conference proceedings, 2005, p. 165-168, article id 1597015Conference paper (Refereed)
    Abstract [en]

    Range imaging is often used in classification of objects in process industry. The speed of inspection needs to be high, so it does not become the bottleneck in the process. This paper presents an FPGA based architecture for range imaging. Using centre of gravity it calculates the range positions from 2D images. The results show that the proposed architecture can process range values with a performance up to 150 Msamples per second. Thus, using cheep standard technology we can achieve up to 3 times higher performance than expensive state-of-the-art high performance smart-cameras.

  • 25.
    Malik, Abdul Waheed
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design. COMSATS Institute of Information Technology, Abbottabad, Pakistan.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Anwar, Qaiser
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Johansen, Tor Arne
    Norwegian University of Science and Technology, Trondheim, Norway .
    Shahzad, Khurram
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Real Time Decoding of Color Symbol for Optical Positioning System2015In: International Journal of Advanced Robotic Systems, ISSN 1729-8806, E-ISSN 1729-8814, Vol. 12, no 5Article in journal (Refereed)
    Abstract [en]

    This paper presents the design and real-time decoding of a color symbol that can be used as a reference marker for optical navigation. The designed symbol has a circular shape and is printed on paper using two distinct colors. This pair of colors is selected based on the highest achievable signal to noise ratio. The symbol is designed to carry eight bit information. Real time decoding of this symbol is performed using a heterogeneous combination of Field Programmable Gate Array (FPGA) and a microcontroller.  An image sensor having a resolution of 1600 by 1200 pixels is used to capture images of symbols in complex backgrounds. Dynamic image segmentation, component labeling and feature extraction was performed on the FPGA. The region of interest was further computed from the extracted features. Feature data belonging to the symbol was sent from the FPGA to the microcontroller. Image processing tasks are partitioned between the FPGA and microcontroller based on data intensity. Experiments were performed to verify the rotational independence of the symbols. The maximum distance between camera and symbol allowing for correct detection and decoding was analyzed. Experiments were also performed to analyze the number of generated image components and sub-pixel precision versus different light sources and intensities. The proposed hardware architecture can process up to 55 frames per second for accurate detection and decoding of symbols at two Megapixels resolution. The power consumption of the complete system is 342mw.

  • 26.
    Malik, Abdul Waheed
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Cheng, Xin
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Real-time Component Labelling with Centre of Gravity Calculation on FPGA2011In: 2011 Proceedings of Sixth International Conference on Systems, 2011Conference paper (Refereed)
    Abstract [en]

    In this paper we present a hardware unit for real time component labelling with Centre of Gravity (COG) calculation. The main targeted application area is light spots used as references for robotic navigation. COG calculation can be done in parallel with a single pass component labelling unit without first having to resolve merged labels. We present hardware architecture suitable for implementation of this COG unit on Field programmable Gate Arrays (FPGA). As result, we get high frame speed, low power and low latency. The device utilization and estimated power dissipation are reported for Xilinx Virtex II pro device simulated at 86 VGA sized frames per second. Maximum speed is 410 frames per second at 126 MHz clock.

  • 27.
    Malik, Abdul Waheed
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Imran, Muhammad
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Hardware Architecture for Real-time  Computation of Image Component Feature Descriptors on a FPGA2014In: International Journal of Distributed Sensor Networks, ISSN 1550-1329, E-ISSN 1550-1477, p. Art. no. 815378-Article in journal (Refereed)
    Abstract [en]

    This paper describes a hardwarearchitecture for real-time image component labelingand the computation of image component featuredescriptors. These descriptors are object relatedproperties used to describe each image component.Embedded machine vision systems demand a robustperformance, power efficiency as well as minimumarea utilization, depending on the deployedapplication. In the proposed architecture, the hardwaremodules for component labeling and featurecalculation run in parallel. A CMOS image sensor(MT9V032), operating at a maximum clock frequencyof 27MHz, was used to capture the images. Thearchitecture was synthesized and implemented on aXilinx Spartan-6 FPGA. The developed architecture iscapable of processing 390 video frames per second ofsize 640x480 pixels. Dynamic power consumption is13mW at 86 frames per second.

  • 28.
    Malik, Abdul Waheed
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Meng, Xiaozhou
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Imran, Muhammad
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Real-Time machine vision system using FPGA and soft-core processor2012In: Proceedings of SPIE - The International Society for Optical Engineering, SPIE - International Society for Optical Engineering, 2012, p. Art. no. 84370Z-Conference paper (Refereed)
    Abstract [en]

    This paper presents a machine vision system for real-time computation of distance and angle of a camera from reference points in the environment. Image pre-processing, component labeling and feature extraction modules were modeled at Register Transfer (RT) level and synthesized for implementation on field programmable gate arrays (FPGA). The extracted image component features were sent from the hardware modules to a soft-core processor, MicroBlaze, for computation of distance and angle. A CMOS imaging sensor operating at a clock frequency of 27MHz was used in our experiments to produce a video stream at the rate of 75 frames per second. Image component labeling and feature extraction modules were running in parallel having a total latency of 13ms. The MicroBlaze was interfaced with the component labeling and feature extraction modules through Fast Simplex Link (FSL). The latency for computing distance and angle of camera from the reference points was measured to be 2ms on the MicroBlaze, running at 100 MHz clock frequency. In this paper, we present the performance analysis, device utilization and power consumption for the designed system. The FPGA based machine vision system that we propose has high frame speed, low latency and a power consumption that is much lower compared to commercially available smart camera solutions. © 2012 SPIE.

  • 29.
    Malik, Abdul Waheed
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Palaniappan, Prasanna Kumar
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Comparison of Three Smart Camera Architectures for Real-time Machine Vision System2013In: International Journal of Advanced Robotic Systems, ISSN 1729-8806, E-ISSN 1729-8814, Vol. 10, p. Art. no. 402-Article in journal (Refereed)
    Abstract [en]

    This paper presents a machine vision system for real-time computation of distance and angle of a camera from a set of reference points located on a target board. Three different smart camera architectures were explored to compare performance parameters such as power consumption, frame speed and latency.  Architecture 1 consists of hardware machine vision modules modeled at Register Transfer (RT) level and a soft-core processor on a single FPGA chip. Architecture 2 is commercially available software based smart camera, Matrox Iris GT. Architecture 3 is a two-chip solution composed of hardware machine vision modules on FPGA and an external micro-controller. Results from a performance comparison show that Architecture 2 has higher latency and consumes much more power than Architecture 1 and 3. However, Architecture 2 benefits from an easy programming model. Smart camera system with FPGA and external microcontroller has lower latency and consumes less power as compared to single FPGA chip having hardware modules and soft-core processor.

  • 30.
    Meng, Xiaozhou
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Haoming, Zeng
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Portability Analysis of Soft Microprocessor for FPGA2012In: 2012 Mediterranean Conference on Embedded Computing, MECO 2012, IEEE conference proceedings, 2012, p. 5-8Conference paper (Refereed)
    Abstract [en]

    This paper discusses the portability issues of soft microprocessor used on FPGA platform. The problems of maintaining a long life cycle system related to soft microprocessor’s portability is emphasized. Three soft microprocessors’ portability was analyzed in the experiments, which represent three types of soft microprocessor groups. The result shows that the system with commercial licensed vendor independent soft microprocessor possesses higher portability and reliability and it is the preferred alternative for designing a long life cycle system. The result from the paper can give guidance to the designers who suffer from microprocessor obsolescence problems.

  • 31.
    Meng, Xiaozhou
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Design Technology Selection for Obsolescence Management Cost AvoidancManuscript (preprint) (Other academic)
    Abstract [en]

    Component obsolescence problems may occur in systems with a life cycle longer than that of one or more of their components, such as automotive, avionics, military application, etc. This paper presents how the design technology selection will impact upon obsolescence management costs for a long life cycle system. Several hardware platforms such as commercial off-the-shelf (COTS) and FPGA are discussed. FPGA design technology is emphasized, and intellectual property (IP) portability is discussed which would affect the redesign costs for obsolescence management. Moreover, embedded software is also a crucial part in relation to long life cycle system sustainment.

    An industrial display computer system is used as an experimental system for a case study. Early cost estimation is carried out before the system development. The proposed FPGA system with device independent IPs indicates a cost avoidance of more than 75% compared to the original COTS based system.

  • 32.
    Meng, Xiaozhou
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Embedded System Design with Maintenance  Consideration2011In: Proceedings of the 34th International Convention on Information and Communication Technology, Electronics and Microelectronics, MIPRO, IEEE conference proceedings, 2011, p. 124-129Conference paper (Refereed)
    Abstract [en]

    This paper deals with the problems of maintaining a long lifetime embedded system, including obsolescence, function change requirement or technology migration etc. The aim of the presented work is to analyze the maintainability of long lifetime embedded systems for different design technologies. FPGA platform solutions are proposed in order to ease the system maintenance. Different platform cases are evaluated by analyzing the essence of each case and the consequences of different risk scenarios during system maintenance. Finally, the conclusion is drawn that the FPGA platform with vendor and device independent soft IP is the best choice.

  • 33.
    Meng, Xiaozhou
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Portability analysis of an M-JPEG decoder IP from OpenCores2011In: SIES 2011 - 6th IEEE International Symposium on Industrial Embedded Systems, Conference Proceedings, IEEE conference proceedings, 2011, p. 79-82Conference paper (Refereed)
    Abstract [en]

    The reuse of predefined Intellectual Property (IP) can shorten development times and help the designer to meet time-to-market requirements for embedded systems. Using FPGA IP in a proper way can also mitigate the component obsolescence problem. System migration between devices is unavoidable, especially for long lifetime embedded systems, so IP portability becomes an important issue for system maintenance. This paper presents a case study analyzing the portability of an FPGA-based M-JPEG decoder IP. The lack of any clear separation between computation and communication is shown to limit the decoder's portability with respect to different communication interfaces. Technology and tool dependent firmware IP components are often supplied by FPGA vendors. It is possible for these firm IP components to reduce development time. However, the use of these technology and tool dependent firmware specifications within the M-JPEG decoder is shown to limit the decoder's portability with respect to development tools and FPGA vendors.

  • 34.
    Meng, Xiaozhou
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Soft-IP Interface Modification Methodology2011In: Proceedings of 2011 International Conference on Information and Electronics Engineering, 2011Conference paper (Refereed)
    Abstract [en]

    The reuse of predefined Intellectual Property (IP) can lead to great success in system design and help the designer to meet time-to-market requirements. A soft IP usually needs some customization and integration efforts rather than plug-and-play. Communication interface mismatch is one of the problems that integrators often meet. This paper suggests a soft-IP interface modification methodology (SIPIMM) for systems on Field Programmable Gate Array (FPGA) SIPIMM targets an interface-based soft IP model which is introduced to ease the interface modification and interface reuse. A case study of an open-source IP is presented using SIPIMM for system integration.

  • 35.
    Meng, Xiaozhou
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Olsson, Leif
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Component obsolescence management model for long life cycle embedded system2012In: AUTOTESTCON (Proceedings), Anaheim, California: IEEE conference proceedings, 2012, p. 19-24Conference paper (Refereed)
    Abstract [en]

    This paper discusses the component obsolescence problem and presents a mathematic model for life cycle analysis of long life cycle embedded system maintenance. This model can estimate minimized management costs for different system architecture. Matlab is used to generate a graph and Lingo is used for linear programming. A simple CAN controller system case study is shown to apply this model. A minimized management cost and an optimized management time schedule are given as the result. The responses from the experiments of the model meet our expectation. Although the model has lots of simplifications and limitations, it can give management strategy guidance to the designers who suffer from component obsolescence problems. 

  • 36.
    Meng, Xiaozhou
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Olsson, Leif
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information and Communication systems.
    Strategic Proactive Obsolescence Management Model2014In: IEEE Transactions on Components, Packaging, and Manufacturing Technology, ISSN 2156-3950, E-ISSN 2156-3985, Vol. 4, no 6, p. 1099-1108Article in journal (Refereed)
    Abstract [en]

    When there is a demand larger than the corresponding number of components in stock, obsolescence problems may occur for those systems with a life cycle longer than that of one or more of their components, such as automotive, avionics, military application, etc. This paper discusses the electronic component obsolescence problem and presents a formal mathematical strategic proactive obsolescence management model for long life cycle systems.

    The model presented in this paper utilizes redesign and last-time-buy (LTB) as two management methods. LTB cost is estimated by unit cost, demand quantities, buffer, discount rate and holding cost. Redesign cost is associated with component type and quantities.

    This model can estimate the minimum management costs for a system with different architectures. It consists of two parts. The first is to generate a graph, which is in the form of an obsolescence management diagram. A segments table containing the data of this diagram is calculated and prepared for optimization at a second step. This second part is to find the minimum cost for system obsolescence management. Mixed integer linear programming (MILP) is used to calculate the minimum management cost and schedule. The model is open sourced allowing other research groups to freely download and modify it.

    A display and control system case study is shown to apply this model practically. A reactive manner is presented as a comparison. The result of the strategic proactive management model shows significant cost avoidance as compared to the reactive manner.

  • 37.
    Norell, Håkan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Automatic Hardware Synthesis of Spatial Memory Models for Real-Time Image Processing Systems2003In: Proceedings of IEEE Norchip Conference 2003: Riga, Latvia, Nov 10-11, 2003, 2003, p. 171-175Conference paper (Refereed)
  • 38.
    Nyström, Jonas
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Gradin, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    An experimental study of the chipping process with focus on energy consumption and chipping angles2018In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 33, no 3, p. 460-467Article in journal (Refereed)
    Abstract [en]

    A series of chipping experiments were performed under both dynamic and quasi-static conditions in a laboratory wood chipper (dynamic) and in a MTS-servohydraulic testing machine (quasi-static). One aim with the experiments was to investigate the rate dependency of the energy consumption during chipping. Another aim was to try to determine the load per unit knife edge length required to initiate cutting. The experiments were carried out using different combinations of spout and edge angles. It was found that for large edge angles (keeping the spout angle constant at 30 °30^\circ ) there was a slight rate dependency such that the energy consumption was larger at higher cutting rates which is quite in opposite of what is expected if wood is assumed to be a viscoelastic material. It was also found that to determine the force at initiation of cutting, is not a trivial task. Both Acoustic Emission monitoring and visual inspection was used to this end. The wood species used in this study was pine (Pinus silvestris). 

  • 39.
    O'Nils, Mattias
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Lilljefjäll, P-R.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Data Partitioning for Parallel Implementation of Real-Time Video Processing Systems2005In: Proceedings of the 2005 European Conference on Circuit Theory and Design: vol. 1, IEEE conference proceedings, 2005, Vol. 1, p. 213-216, article id 1522948Conference paper (Refereed)
    Abstract [en]

    The main reason for using data partitioning for a video processing system is the increase in performance it offers. This paper presents a comparison of the buffering requirements for different data partitioning methods used in video processing systems. The analysis shows that the buffer storage required for the implementation of video systems is highly dependent on the partitioning strategy. The results indicate that partitioning the tasks vertically is by far the most efficient method when considering buffer sizes.

  • 40.
    O'Nils, Mattias
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Norell, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    A Comparison between Local and Global Memory Allocation for FPGA Implementation of Real-Time Video Processing Systems2004In: Proceedings of the IEEE International Conference on Signals and Electronic Systems, 2004Conference paper (Refereed)
    Abstract [en]

    This paper presents a comparison of local and global memory allocation for implementation of real-time video processing systems on FPGAs. The paper compares new methods to perform memory allocation using single and dual port block RAMs to memory allocation methods found in the literature. This investigation shows that the use of global allocation can reduce the memory size by up to 75 % for the two presented video processing systems.

  • 41.
    O'Nils, Mattias
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Lawal, Najeem
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    High-Level SystemC Synthesis for FPGA based Real-Time Video Processing Systems2006In: Proceedings of the FPGA World Conference, 2006Conference paper (Refereed)
  • 42.
    Rydblom, Staffan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Droplet Imaging Instrument Metrology Instrument for Icing Condition Detection2016In: 2016 IEEE INTERNATIONAL CONFERENCE ON IMAGING SYSTEMS AND TECHNIQUES (IST), IEEE, 2016, p. 66-71, article id 7738200Conference paper (Refereed)
    Abstract [en]

    An instrument for measuring water droplets is described and constructed. It is designed to measure the volume concentration and the size distribution of droplets in order to detect icing conditions in a natural fog. The instrument works by shadowgraph imaging, with a collimated blue LED as background illumination. We show how to use a reference object to obtain a calibration of the droplet size and the measurement volume. These properties are derived from a measurement of the object's shadow intensity and its edge second derivative. From the size of every measured droplet and its expected detection volume, a measure of the liquid water content (LWC) and the median volume diameter (MVD) can be estimated. The instrument can be used for continuous measurement in a remote weather-exposed location and is tested in a small environment chamber. We also describe this chamber and how we can change the LWC using an ultrasonic fog generator and a fan.

  • 43.
    Rydblom, Staffan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Liquid Water Content and Droplet Sizing Shadowgraph Measuring System for Wind Turbine Icing Detection2016In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 16, no 8, p. 2714-2725, article id 7384444Article in journal (Refereed)
    Abstract [en]

    This study shows that the liquid water content (LWC) and the median volume diameter (MVD) can be derived from images of water droplets using a shadowgraph imaging system with incoherent LED illumination.

    Icing on structures such as a wind turbine is the result of a combination of LWC and MVD and other parameters like temperature, humidity and wind speed. Today, LWC and MVD are not commonly measured for wind turbines. Systems for measuring these properties are often expensive or impractical in terms of location or remote reading. The aim of this study is to gain knowledge about how to design a single instrument based on imaging that has the ability to measure these properties with enough precision and accuracy to detect icing conditions for wind turbines.

    A method to calculate both the LWC and the MVD from the same images is described in this paper. The size of one droplet is determined by measuring the shadow created by the droplet in background illumination. The concentration is calculated by counting the measured droplets and estimating the volumes in which these droplets can be observed.

    In the described study, the observation volume is shown to be dependent on the particle size and the signal to noise ratio (SNR) for each measured particle. An expected coefficient of variation of the LWC depending on the droplet size is shown to be 2.4 percent for droplets 10 µm in diameter and 1.6 percent for 25 µm droplets. This is based on an error estimation of the laboratory measurements calibrated using a micrometer dot scale.

  • 44.
    Rydblom, Staffan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Particle Measurement Volume and Light Intensity in a Shadowgraph Imaging System2018In: IST 2018 - IEEE International Conference on Imaging Systems and Techniques, Proceedings, IEEE, 2018, article id 8577170Conference paper (Refereed)
    Abstract [en]

    A method is sought to find the measurement volume of an optical instrument for particle measurement is sought. The study shows that the measurement volume depends on a combination of the optical homogeneity of the illumination light and the camera system. The result from a mix of illumination cases and positions shows that, if the true size and the background brightness are known, the measurement volume can be determined with an average precision of four percent using adual term exponential fit. Using a lens with lower magnification increases the measurement volume since both the field of viewand the depth of field increase. However, a larger field of view increases the required amount of light as well as the sensitivity to other optical errors.

  • 45.
    Rydblom, Staffan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Olsson, Esbjörn
    Swedish Meteorol & Hydrol Inst (SMHI), Sundsvall.
    Field Study of LWC and MVD Using the Droplet Imaging Instrument2019In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 68, no 2, p. 614-622Article in journal (Refereed)
    Abstract [en]

    The droplet imaging instrument (DII) is a new instrument for cost-effective in situ measurements of the size and concentration of water droplets. The droplet size distribution and the concentration of atmospheric liquid water are important for the prediction of icing on structures, such as wind turbines. To improve the predictions of icing, there is a need to explore cost-effective working solutions. Through imaging, a wide range of droplet sizes can be measured. This paper describes a study of the atmospheric liquid water content and the median volume diameter using the DII and a commercial reference instrument--the cloud droplet probe 2 from Droplet Measurement Technologies Inc. The measurement is done at a weather measurement station in mid-Sweden. For a second validation, the result is compared with predictions using a numerical weather prediction model. The size measurement of the DII is verified using polymer microspheres of four known size distributions. The study shows that the DII measurement is precise, but there is a systematic difference between the two compared instruments. It also shows that droplets larger than 50 μm in diameter are occasionally measured, which we believe is important for the prediction of icing.

  • 46.
    Rydblom, Stefani Alita Leona
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Measurement of Atmospheric Icing and DropletsManuscript (preprint) (Other academic)
  • 47.
    Svelander, Lars
    et al.
    Svelander Holding AB.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design.
    Belysningsanordning för fordon2013Patent (Other (popular science, discussion, etc.))
    Abstract [sv]

    Belysningsanordning för avgivande av elektromagnetisk strålning för belysningsändamål eller liknande från ett fordon. Belysningsanordningen innefattar minst en enhet i vilken elektromagnetisk strålning genereras av minst en strålningsavgivande enhet, vars genererade elektromagnetiska strålning avges från belysningsanordningen av minst en strålningsavgivande enhet under bildandet av minst en ljuskägla vilken är justerbart anordnad med minst ett styrsystem. Belysningsanordningen innefattar minst en bildsensor vars insamlade information bearbetas i minst en datoriserad bildanalysenhet. Ljuskäglans justerbarhet uppnås av att ljuskäglan är uppdelad i ett flertal sektorer och att den avgivna ljusintensiteten i respektive sektor kan styras individuellt med utgångspunkt från information insamlad av bildsensorn och som bearbetats av bildanalysenheten. Patentansökan innefattar även ett förfarande för användning av belysningsanordningen.

  • 48.
    Thim, Jan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Manuilskiy, A
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    O´Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Lindgren, J
    Lidén, J
    The Impact of Surface Movement in Online Paper Topgraphy Cahracerization Using Light Triangulation2009In: Proceedings fo the Papermaker´s Research Symposium, 2009Conference paper (Refereed)
  • 49.
    Thim, Jan
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    O'Nils, Mattias
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Manuilskiy, Anatoliy
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Thörnberg, Benny
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Information Technology and Media.
    Simulating the Impact of Topographical Microstructures on Triangulation Measurement Setups using Matlab2008In: Proceedings of Nordic MATLAB User Conference, 2008Conference paper (Refereed)
    Abstract [en]

    The paper manufacturing industry is currently exploring the possibility of measuring micro structural topography online in a paper manufacturing machine, which is intended to lead to a more precise measure of the paper quality reel to reel and a more efficient use of raw material. This paper presents a Matlab simulation model that can be used to configure such measurement readout systems, and includes a demonstration of the model in use. The model will also be used for research purposes in order to assist in gaining a better understanding of both the limitations and possibilities of such measurement systems. In this regard the angular shading of microstructures and Centre of Gravity (CoG) functions are included in the attributes that require further exploration.

     

  • 50. Thörnberg, Benny
    Medical Environment Interface1992Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The present invention provides a method and an apparatus to facilitate feeding of electric signals, achieved in a defined area of medical electric environment, to and from auxiliary equipment, specifically a so called Personal Computer (PC), without the necessity that such auxiliary equipment fulfill the requirements necessary for use within the area of medical electric environment. The apparatus includes an isolation device having its own power supply which is approved for the medical electric environment according to the International Standard IEC 601-1, an electronic buffering device connected to a CCD sensor and multiwire cables between the auxiliary equipment and the isolation device and the buffering device and the isolation device, respectively, facilitating parallel signal communication, whereby the isolation device includes a number of electromagnetic and/or optoelectric interfaces corresponding to the number of wires connecting the CCD sensor and the auxiliary equipment positioned in an area of non-medical electric environment.

12 1 - 50 of 63
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