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  • 1.
    Abbaspour, Sara
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Engineering Department, University of Qom, Iran.
    Fotouhi, F.
    Engineering Department, University of Qom, Iran.
    Sedaghatbaf, A.
    RISE Research Institutes of Sweden, Sweden.
    Fotouhi, Hossein
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Vahabi, Maryam
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. ABB Corporate Research, Sweden.
    Lindén, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    A comparative analysis of hybrid deep learning models for human activity recognition2020Ingår i: Sensors, E-ISSN 1424-8220, Vol. 20, nr 19, s. 1-14, artikel-id 5707Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recent advances in artificial intelligence and machine learning (ML) led to effective methods and tools for analyzing the human behavior. Human Activity Recognition (HAR) is one of the fields that has seen an explosive research interest among the ML community due to its wide range of applications. HAR is one of the most helpful technology tools to support the elderly’s daily life and to help people suffering from cognitive disorders, Parkinson’s disease, dementia, etc. It is also very useful in areas such as transportation, robotics and sports. Deep learning (DL) is a branch of ML based on complex Artificial Neural Networks (ANNs) that has demonstrated a high level of accuracy and performance in HAR. Convolutional Neural Networks (CNNs) and Recurrent Neural Networks (RNNs) are two types of DL models widely used in the recent years to address the HAR problem. The purpose of this paper is to investigate the effectiveness of their integration in recognizing daily activities, e.g., walking. We analyze four hybrid models that integrate CNNs with four powerful RNNs, i.e., LSTMs, BiLSTMs, GRUs and BiGRUs. The outcomes of our experiments on the PAMAP2 dataset indicate that our proposed hybrid models achieve an outstanding level of performance with respect to several indicative measures, e.g., F-score, accuracy, sensitivity, and specificity. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

  • 2.
    Abbaspour, Sara
    et al.
    Massachusetts Gen Hosp, Dept Neurol, Boston, MA 02114 USA.;Harvard Med Sch, Div Sleep Med, Boston, MA 02114 USA..
    Naber, Autumn
    Ctr Bion & Pain Res, S-43180 Molndal, Sweden.;Chalmers Univ Technol, Dept Elect Engn, S-41296 Gothenburg, Sweden..
    Ortiz-Catalan, Max
    Ctr Bion & Pain Res, S-43180 Molndal, Sweden.;Chalmers Univ Technol, Dept Elect Engn, S-41296 Gothenburg, Sweden.;Sahlgrens Univ Hosp, Operat Area 3, S-43180 Molndal, Sweden.;Univ Gothenburg, Sahlgrenska Acad, Inst Clin Sci, Dept Orthopaed, S-43180 Molndal, Sweden..
    GholamHosseini, Hamid
    Auckland Univ Technol, Dept Elect & Elect Engn, Auckland 1010, New Zealand..
    Lindén, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Real-Time and Offline Evaluation of Myoelectric Pattern Recognition for the Decoding of Hand Movements2021Ingår i: Sensors, E-ISSN 1424-8220, Vol. 21, nr 16, artikel-id 5677Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pattern recognition algorithms have been widely used to map surface electromyographic signals to target movements as a source for prosthetic control. However, most investigations have been conducted offline by performing the analysis on pre-recorded datasets. While real-time data analysis (i.e., classification when new data becomes available, with limits on latency under 200-300 milliseconds) plays an important role in the control of prosthetics, less knowledge has been gained with respect to real-time performance. Recent literature has underscored the differences between offline classification accuracy, the most common performance metric, and the usability of upper limb prostheses. Therefore, a comparative offline and real-time performance analysis between common algorithms had yet to be performed. In this study, we investigated the offline and real-time performance of nine different classification algorithms, decoding ten individual hand and wrist movements. Surface myoelectric signals were recorded from fifteen able-bodied subjects while performing the ten movements. The offline decoding demonstrated that linear discriminant analysis (LDA) and maximum likelihood estimation (MLE) significantly (p < 0.05) outperformed other classifiers, with an average classification accuracy of above 97%. On the other hand, the real-time investigation revealed that, in addition to the LDA and MLE, multilayer perceptron also outperformed the other algorithms and achieved a classification accuracy and completion rate of above 68% and 69%, respectively.

  • 3.
    Abdelakram, Hafid
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Difallah, Sabrina
    Laboratory of Instrumentation, University of Sciences and Technology Houari Boumediene, 16111 Algiers, Algeria.
    Alves, Camille
    Assistive Technology Lab (NTA), Faculty of Electrical Engineering, Federal University of Uberlandia, Uberlandia 38408-100, Brazil.
    Abdullah, Saad
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Folke, Mia
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Lindén, Maria
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Kristoffersson, Annica
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    State of the Art of Non-Invasive Technologies for Bladder Monitoring: A Scoping Review2023Ingår i: Sensors, E-ISSN 1424-8220, Vol. 23, nr 5, artikel-id 2758Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Bladder monitoring, including urinary incontinence management and bladder urinary volume monitoring, is a vital part of urological care. Urinary incontinence is a common medical condition affecting the quality of life of more than 420 million people worldwide, and bladder urinary volume is an important indicator to evaluate the function and health of the bladder. Previous studies on non-invasive techniques for urinary incontinence management technology, bladder activity and bladder urine volume monitoring have been conducted. This scoping review outlines the prevalence of bladder monitoring with a focus on recent developments in smart incontinence care wearable devices and the latest technologies for non-invasive bladder urine volume monitoring using ultrasound, optical and electrical bioimpedance techniques. The results found are promising and their application will improve the well-being of the population suffering from neurogenic dysfunction of the bladder and the management of urinary incontinence. The latest research advances in bladder urinary volume monitoring and urinary incontinence management have significantly improved existing market products and solutions and will enable the development of more effective future solutions.

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  • 4.
    Abdelakram, Hafid
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system. Textile Materials Technology, Department of Textile Technology, Faculty of Textiles, Engineering and Business Swedish School of Textiles, University of Borås, 503 32 Borås, Sweden.
    Gunnarsson, Emanuel
    Textile Materials Technology, Department of Textile Technology, Faculty of Textiles, Engineering and Business Swedish School of Textiles, University of Borås, 503 32 Borås, Sweden.
    Ramos, Alberto
    Textile Materials Technology, Department of Textile Technology, Faculty of Textiles, Engineering and Business Swedish School of Textiles, University of Borås, 503 32 Borås, Sweden;UDIT—University of Design, Innovation and Technology, 28016 Madrid, Spain.
    Rödby, Kristian
    Textile Materials Technology, Department of Textile Technology, Faculty of Textiles, Engineering and Business Swedish School of Textiles, University of Borås, 503 32 Borås, Sweden.
    Abtahi, Farhad
    Institute for Clinical Science, Intervention and Technology, Karolinska Institutet, 141 83 Stockholm, Sweden;Department of Medical Care Technology, Karolinska University Hospital, 141 57 Huddinge, Sweden;Department of Clinical Physiology, Karolinska University Hospital, 141 57 Huddinge, Sweden.
    Bamidis, Panagiotis D.
    Lab of Medical Physics and Digital Innovation, School of Medicine, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece.
    Billis, Antonis
    Lab of Medical Physics and Digital Innovation, School of Medicine, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece.
    Papachristou, Panagiotis
    Academic Primary Health Care Center, Region Stockholm, 104 31 Stockholm, Sweden;Division of Family Medicine and Primary Care, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 83 Stockholm, Sweden.
    Seoane, Fernando
    Textile Materials Technology, Department of Textile Technology, Faculty of Textiles, Engineering and Business Swedish School of Textiles, University of Borås, 503 32 Borås, Sweden;Institute for Clinical Science, Intervention and Technology, Karolinska Institutet, 141 83 Stockholm, Sweden;Department of Medical Care Technology, Karolinska University Hospital, 141 57 Huddinge, Sweden;Department of Clinical Physiology, Karolinska University Hospital, 141 57 Huddinge, Sweden.
    Sensorized T-Shirt with Intarsia-Knitted Conductive Textile Integrated Interconnections: Performance Assessment of Cardiac Measurements during Daily Living Activities2023Ingår i: Sensors, E-ISSN 1424-8220, Vol. 23, nr 22, s. 9208-9208Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The development of smart wearable solutions for monitoring daily life health status is increasingly popular, with chest straps and wristbands being predominant. This study introduces a novel sensorized T-shirt design with textile electrodes connected via a knitting technique to a Movesense device. We aimed to investigate the impact of stationary and movement actions on electrocardiography (ECG) and heart rate (HR) measurements using our sensorized T-shirt. Various activities of daily living (ADLs), including sitting, standing, walking, and mopping, were evaluated by comparing our T-shirt with a commercial chest strap. Our findings demonstrate measurement equivalence across ADLs, regardless of the sensing approach. By comparing ECG and HR measurements, we gained valuable insights into the influence of physical activity on sensorized T-shirt development for monitoring. Notably, the ECG signals exhibited remarkable similarity between our sensorized T-shirt and the chest strap, with closely aligned HR distributions during both stationary and movement actions. The average mean absolute percentage error was below 3%, affirming the agreement between the two solutions. These findings underscore the robustness and accuracy of our sensorized T-shirt in monitoring ECG and HR during diverse ADLs, emphasizing the significance of considering physical activity in cardiovascular monitoring research and the development of personal health applications.

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  • 5.
    Aghaeinezhadfirouzja, S.
    et al.
    Department of Electronics Engineering, Shanghai Jiao Tong University, Shanghai, China.
    Liu, H.
    Department of Electronics Engineering, Shanghai Jiao Tong University, Shanghai, China.
    Balador, Ali
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. RISE SICS Västerås, Sweden.
    Practical 3-D beam pattern based channel modeling for multi-polarized massive MIMO systems2018Ingår i: Sensors, E-ISSN 1424-8220, Vol. 18, nr 4, artikel-id 1186Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, a practical non-stationary three-dimensional (3-D) channel models for massive multiple-input multiple-output (MIMO) systems, considering beam patterns for different antenna elements, is proposed. The beam patterns using dipole antenna elements with different phase excitation toward the different direction of travels (DoTs) contributes various correlation weights for rays related towards/from the cluster, thus providing different elevation angle of arrivals (EAoAs) and elevation angle of departures (EAoDs) for each antenna element. These include the movements of the user that makes our channel to be a non-stationary model of clusters at the receiver (RX) on both the time and array axes. In addition, their impacts on 3-D massive MIMO channels are investigated via statistical properties including received spatial correlation. Additionally, the impact of elevation/azimuth angles of arrival on received spatial correlation is discussed. Furthermore, experimental validation of the proposed 3-D channel models on azimuth and elevation angles of the polarized antenna are specifically evaluated and compared through simulations. The proposed 3-D generic models are verified using relevant measurement data.

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  • 6.
    Ali, T.
    et al.
    Department of Civil, Architectural and Environmental System Engineering, Sungkyunkwan University, Suwon, 16419, South Korea.
    Haider, W.
    Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon, 16419, South Korea.
    Ali, Nazakat
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Aslam, M.
    Department of Artificial Intelligence, Sejong University, Seoul, 05006, South Korea.
    A Machine Learning Architecture Replacing Heavy Instrumented Laboratory Tests: In Application to the Pullout Capacity of Geosynthetic Reinforced Soils2022Ingår i: Sensors, E-ISSN 1424-8220, Vol. 22, nr 22, artikel-id 8699Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For economical and sustainable benefits, conventional retaining walls are being replaced by geosynthetic reinforced soil (GRS). However, for safety and quality assurance purposes, prior tests of pullout capacities of these materials need to be performed. Conventionally, these tests are conducted in a laboratory with heavy instruments. These tests are time-consuming, require hard labor, are prone to error, and are expensive as a special pullout machine is required to perform the tests and acquire the data by using a lot of sensors and data loggers. This paper proposes a data-driven machine learning architecture (MLA) to predict the pullout capacity of GRS in a diverse environment. The results from MLA are compared with actual laboratory pullout capacity tests. Various input variables are considered for training and testing the neural network. These input parameters include the soil physical conditions based on water content and external loading applied. The soil used is a locally available weathered granite soil. The input data included normal stress, soil saturation, displacement, and soil unit weight whereas the output data contains information about the pullout strength. The data used was obtained from an actual pullout capacity test performed in the laboratory. The laboratory test is performed according to American Society for Testing and Materials (ASTM) standard D 6706-01 with little modification. This research shows that by using machine learning, the same pullout resistance of a geosynthetic reinforced soil can be achieved as in laboratory testing, thus saving a lot of time, effort, and money. Feedforward backpropagation neural networks with a different number of neurons, algorithms, and hidden layers have been examined. The comparison of the Bayesian regularization learning algorithm with two hidden layers and 12 neurons each showed the minimum mean square error (MSE) of 3.02 × 10−5 for both training and testing. The maximum coefficient of regression (R) for the testing set is 0.999 and the training set is 0.999 for the prediction interval of 99%. 

  • 7.
    Alirezaie, Marjan
    et al.
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Renoux, Jennifer
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Köckemann, Uwe
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Kristoffersson, Annica
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Karlsson, Lars
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    Blomqvist, Eva
    RISE SICS East, Linköping, Sweden.
    Tsiftes, Nicolas
    RISE SICS, Stockholm, Sweden.
    Voigt, Thiemo
    RISE SICS, Stockholm, Sweden.
    Loutfi, Amy
    Örebro universitet, Institutionen för naturvetenskap och teknik.
    An Ontology-based Context-aware System for Smart Homes: E-care@home2017Ingår i: Sensors, E-ISSN 1424-8220, Vol. 17, nr 7, artikel-id 1586Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Smart home environments have a significant potential to provide for long-term monitoring of users with special needs in order to promote the possibility to age at home. Such environments are typically equipped with a number of heterogeneous sensors that monitor both health and environmental parameters. This paper presents a framework called E-care@home, consisting of an IoT infrastructure, which provides information with an unambiguous, shared meaning across IoT devices, end-users, relatives, health and care professionals and organizations. We focus on integrating measurements gathered from heterogeneous sources by using ontologies in order to enable semantic interpretation of events and context awareness. Activities are deduced using an incremental answer set solver for stream reasoning. The paper demonstrates the proposed framework using an instantiation of a smart environment that is able to perform context recognition based on the activities and the events occurring in the home.

  • 8.
    Balador, Ali
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Kouba, A.
    Polytechnic Institute of Porto, Porto 4249-015, Portugal.
    Cassioli, D.
    University of L'Aquila, L'Aquila, 67100, Italy.
    Foukalas, F.
    Technical University of Denmark, Kongens Lyngby, 2800, Denmark.
    Severino, R.
    Polytechnic Institute of Porto, Porto 4249-015, Portugal.
    Stepanova, D.
    Finnish Meteorological Institute, 99600 Sodankylä, Finland.
    Agosta, G.
    Politecnico di Milano ,Via G. Ponzio 32, Milano, I-20133, Italy.
    Xie, J.
    Group Technology & Research, DNV GL, Veritasveien 1, Norway.
    Pomante, L.
    University of L'Aquila, L'Aquila, 67100, Italy.
    Mongelli, M.
    CNR-IEIIT ,via De Marini 6, Genova, 16149, Italy.
    Pierini, P.
    Intecs S.p.A., Pisa, 56121, Italy.
    Petersen, S.
    SINTEF ICT, Trondheim, 7465, Norway.
    Sukuvaara, T.
    Finnish Meteorological Institute, 99600 Sodankylä, Finland.
    Wireless Communication Technologies for Safe Cooperative Cyber Physical Systems2018Ingår i: Sensors, E-ISSN 1424-8220, Vol. 18, nr 11, artikel-id 4075Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cooperative Cyber-Physical Systems (Co-CPSs) can be enabled using wireless communication technologies, which in principle should address reliability and safety challenges. Safety for Co-CPS enabled by wireless communication technologies is a crucial aspect and requires new dedicated design approaches. In this paper, we provide an overview of five Co-CPS use cases, as introduced in our SafeCOP EU project, and analyze their safety design requirements. Next, we provide a comprehensive analysis of the main existing wireless communication technologies giving details about the protocols developed within particular standardization bodies. We also investigate to what extent they address the non-functional requirements in terms of safety, security and real time, in the different application domains of each use case. Finally, we discuss general recommendations about the use of different wireless communication technologies showing their potentials in the selected real-world use cases. The discussion is provided under consideration in the 5G standardization process within 3GPP, whose current efforts are inline to current gaps in wireless communications protocols for Co-CPSs including many future use cases.

  • 9.
    Balador, Ali
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Uhlemann, Elisabeth
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Calafate, C. T.
    Universitat Politècnica de València, València, Spain.
    Cano, J. -C
    Universitat Politècnica de València, València, Spain.
    Supporting beacon and event-driven messages in vehicular platoons through token-based strategies2018Ingår i: Sensors, E-ISSN 1424-8220, Vol. 18, nr 4, artikel-id 955Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Timely and reliable inter-vehicle communications is a critical requirement to support traffic safety applications, such as vehicle platooning. Furthermore, low-delay communications allow the platoon to react quickly to unexpected events. In this scope, having a predictable and highly effective medium access control (MAC) method is of utmost importance. However, the currently available IEEE 802.11p technology is unable to adequately address these challenges. In this paper, we propose a MAC method especially adapted to platoons, able to transmit beacons within the required time constraints, but with a higher reliability level than IEEE 802.11p, while concurrently enabling efficient dissemination of event-driven messages. The protocol circulates the token within the platoon not in a round-robin fashion, but based on beacon data age, i.e., the time that has passed since the previous collection of status information, thereby automatically offering repeated beacon transmission opportunities for increased reliability. In addition, we propose three different methods for supporting event-driven messages co-existing with beacons. Analysis and simulation results in single and multi-hop scenarios showed that, by providing non-competitive channel access and frequent retransmission opportunities, our protocol can offer beacon delivery within one beacon generation interval while fulfilling the requirements on low-delay dissemination of event-driven messages for traffic safety applications. 

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  • 10.
    Ballesteros, Joaquin
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Tudela, Alberto J.
    University of Malaga, Malaga, Spain.
    Caro-Romero, J. R.
    University of Malaga, Malaga, Spain.
    Urdiales, C.
    University of Malaga, Malaga, Spain.
    Weight-Bearing Estimation for Cane Users by Using Onboard Sensors2019Ingår i: Sensors, E-ISSN 1424-8220, Vol. 19, nr 3Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mobility is a fundamental requirement for a healthy, active lifestyle. Gait analysis is widely acknowledged as a clinically useful tool for identifying problems with mobility, as identifying abnormalities within the gait profile is essential to correct them via training, drugs, or surgical intervention. However, continuous gait analysis is difficult to achieve due to technical limitations, namely the need for specific hardware and constraints on time and test environment to acquire reliable data. Wearables may provide a solution if users carry them most of the time they are walking. We propose to add sensors to walking canes to assess user's mobility. Canes are frequently used by people who cannot completely support their own weight due to pain or balance issues. Furthermore, in absence of neurological disorders, the load on the cane is correlated with the user condition. Sensorized canes already exist, but often rely on expensive sensors and major device modifications are required. Thus, the number of potential users is severely limited. In this work, we propose an affordable module for load monitoring so that it can be widely used as a screening tool. The main advantages of our module are: (i) it can be deployed in any standard cane with minimal changes that do not affect ergonomics; (ii) it can be used every day, anywhere for long-term monitoring. We have validated our prototype with 10 different elderly volunteers that required a cane to walk, either for balance or partial weight bearing. Volunteers were asked to complete a 10 m test and, then, to move freely for an extra minute. The load peaks on the cane, corresponding to maximum support instants during the gait cycle, were measured while they moved. For validation, we calculated their gait speed using a chronometer during the 10 m test, as it is reportedly related to their condition. The correlation between speed (condition) and load results proves that our module provides meaningful information for screening. In conclusion, our module monitors support in a continuous, unsupervised, nonintrusive way during users' daily routines, plus only mechanical adjustment (cane height) is needed to change from one user to another.

  • 11. Biabani, M.
    et al.
    Fotouhi, Hossein
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Yazdani, N.
    An energy-efficient evolutionary clustering technique for disaster management in IoT networks2020Ingår i: Sensors, E-ISSN 1424-8220, Vol. 20, nr 9, artikel-id 2647Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wireless Sensor Networks (WSNs) are key elements of Internet of Things (IoT) networks which provide sensing and wireless connectivity. Disaster management in smart cities is classified as a safety-critical application. Thus, it is important to ensure system availability by increasing the lifetime of WSNs. Clustering is one of the routing techniques that benefits energy efficiency in WSNs. This paper provides an evolutionary clustering and routing method which is capable of managing the energy consumption of nodes while considering the characteristics of a disaster area. The proposed method consists of two phases. First, we present a model with improved hybrid Particle Swarm Optimization (PSO) and Harmony Search Algorithm (HSA) for cluster head (CH) selection. Second, we design a PSO-based multi-hop routing system with enhanced tree encoding and a modified data packet format. The simulation results for disaster scenarios prove the efficiency of the proposed method in comparison with the state-of-the-art approaches in terms of the overall residual energy, number of live nodes, network coverage, and the packet delivery ratio. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

  • 12.
    Du, Jiaying
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Motion Control i Västerås AB, Västerås, Sweden.
    Gerdtman, C.
    Motion Control i Västerås AB, Västerås, Sweden.
    Lindén, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Signal quality improvement algorithms for MEMS gyroscope-based human motion analysis systems: A systematic review2018Ingår i: Sensors, E-ISSN 1424-8220, Vol. 18, nr 4, artikel-id 1123Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Motion sensors such as MEMS gyroscopes and accelerometers are characterized by a small size, light weight, high sensitivity, and low cost. They are used in an increasing number of applications. However, they are easily influenced by environmental effects such as temperature change, shock, and vibration. Thus, signal processing is essential for minimizing errors and improving signal quality and system stability. The aim of this work is to investigate and present a systematic review of different signal error reduction algorithms that are used for MEMS gyroscope-based motion analysis systems for human motion analysis or have the potential to be used in this area. A systematic search was performed with the search engines/databases of the ACM Digital Library, IEEE Xplore, PubMed, and Scopus. Sixteen papers that focus on MEMS gyroscope-related signal processing and were published in journals or conference proceedings in the past 10 years were found and fully reviewed. Seventeen algorithms were categorized into four main groups: Kalman-filter-based algorithms, adaptive-based algorithms, simple filter algorithms, and compensation-based algorithms. The algorithms were analyzed and presented along with their characteristics such as advantages, disadvantages, and time limitations. A user guide to the most suitable signal processing algorithms within this area is presented.

  • 13.
    Ehn, Maria
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Kristoffersson, Annica
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Clinical sensor-based fall risk assessment at an orthopedic clinic: A case study of the staff’s views on utility and effectiveness2023Ingår i: Sensors, E-ISSN 1424-8220, Vol. 23, nr 4, artikel-id 1904Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In-hospital falls are a serious threat to patient security and fall risk assessment (FRA) is important to identify high-risk patients. Although sensor-based FRA (SFRA) can provide objective FRA, its clinical use is very limited and research to identify meaningful SFRA methods is required. This study aimed to investigate whether examples of SFRA methods might be relevant for FRA at an orthopedic clinic. Situations where SFRA might assist FRA were identified in a focus group interview with clinical staff. Thereafter, SFRA methods were identified in a literature review of SFRA methods developed for older adults. These were screened for potential relevance in the previously identified situations. Ten SFRA methods were considered potentially relevant in the identified FRA situations. The ten SFRA methods were presented to staff at the orthopedic clinic, and they provided their views on the SFRA methods by filling out a questionnaire. Clinical staff saw that several SFRA tasks could be clinically relevant and feasible, but also identified time constraints as a major barrier for clinical use of SFRA. The study indicates that SFRA methods developed for community-dwelling older adults may be relevant also for hospital inpatients and that effectiveness and efficiency are important for clinical use of SFRA.

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  • 14.
    Hussain, Manzoor
    et al.
    Chungbuk Natl Univ, Dept Comp Sci, Cheongju 28644, South Korea..
    Ali, Nazakat
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system. Mälardalen Univ, Sch Innovat Design & Engn, S-72220 Västerås, Sweden..
    Hong, Jang-Eui
    Chungbuk Natl Univ, Dept Comp Sci, Cheongju 28644, South Korea..
    Vision beyond the Field-of-View: A Collaborative Perception System to Improve Safety of Intelligent Cyber-Physical Systems2022Ingår i: Sensors, E-ISSN 1424-8220, Vol. 22, nr 17, artikel-id 6610Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cyber-physical systems (CPSs) that interact with each other to achieve common goals are known as collaborative CPSs. Collaborative CPSs can achieve complex goals that individual CPSs cannot achieve on their own. One of the examples of collaborative CPSs is the vehicular cyber-physical systems (VCPSs), which integrate computing and physical resources to interact with each other to improve traffic safety, situational awareness, and efficiency. The perception system of individual VCPS has limitations on its coverage and detection accuracy. For example, the autonomous vehicle's sensor cannot detect occluded objects and obstacles beyond its field of view. The VCPS can combine its own data with other collaborative VCPSs to enhance perception, situational awareness, accuracy, and traffic safety. This paper proposes a collaborative perception system to detect occluded objects through the camera sensor's image fusion and stitching technique. The proposed collaborative perception system combines the perception of surrounding autonomous driving systems (ADSs) that extends the detection range beyond the field of view. We also applied logistic chaos map-based encryption in our collaborative perception system in order to avoid the phantom information shared by malicious vehicles and improve safety in collaboration. It can provide the real-time perception of occluded objects, enabling safer control of ADSs. The proposed collaborative perception can detect occluded objects and obstacles beyond the field of view that individual VCPS perception systems cannot detect, improving the safety of ADSs. We investigated the effectiveness of collaborative perception and its contribution toward extended situational awareness on the road in the simulation environment. Our simulation results showed that the average detection rate of proposed perception systems was 45.4% more than the perception system of an individual ADS. The safety analysis showed that the response time was increased up to 1 s, and the average safety distance was increased to 1.2 m when the ADSs were using collaborative perception compared to those scenarios in which the ADSs were not using collaborative perception.

  • 15.
    Kaur, R.
    et al.
    School of Engineering, Computer, and Mathematical Sciences, Auckland University of Technology, Auckland, New Zealand.
    Gholamhosseini, H.
    School of Engineering, Computer, and Mathematical Sciences, Auckland University of Technology, Auckland, 1010, New Zealand.
    Sinha, R.
    School of Engineering, Computer, and Mathematical Sciences, Auckland University of Technology, Auckland, 1010, New Zealand.
    Lindén, Maria
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Melanoma Classification Using a Novel Deep Convolutional Neural Network with Dermoscopic Images2022Ingår i: Sensors, E-ISSN 1424-8220, Vol. 22, nr 3, artikel-id 1134Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Automatic melanoma detection from dermoscopic skin samples is a very challenging task. However, using a deep learning approach as a machine vision tool can overcome some challenges. This research proposes an automated melanoma classifier based on a deep convolutional neural network (DCNN) to accurately classify malignant vs. benign melanoma. The structure of the DCNN is carefully designed by organizing many layers that are responsible for extracting low to high-level features of the skin images in a unique fashion. Other vital criteria in the design of DCNN are the selection of multiple filters and their sizes, employing proper deep learning layers, choosing the depth of the network, and optimizing hyperparameters. The primary objective is to propose a lightweight and less complex DCNN than other state-of-the-art methods to classify melanoma skin cancer with high efficiency. For this study, dermoscopic images containing different cancer samples were obtained from the International Skin Imaging Collaboration datastores (ISIC 2016, ISIC2017, and ISIC 2020). We evaluated the model based on accuracy, precision, recall, specificity, and F1-score. The proposed DCNN classifier achieved accuracies of 81.41%, 88.23%, and 90.42% on the ISIC 2016, 2017, and 2020 datasets, respectively, demonstrating high performance compared with the other state-of-the-art networks. Therefore, this proposed approach could provide a less complex and advanced framework for automating the melanoma diagnostic process and expediting the identification process to save a life. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

  • 16.
    Kristoffersson, Annica
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Du, Jiaying
    Motion Control AB, Sweden.
    Ehn, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Performance and Characteristics of Wearable Sensor Systems Discriminating and Classifying Older Adults According to Fall Risk: A Systematic Review2021Ingår i: Sensors, E-ISSN 1424-8220, Vol. 21, nr 17, artikel-id 5863Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Sensor-based fall risk assessment (SFRA) utilizes wearable sensors for monitoring individuals’ motions in fall risk assessment tasks. Previous SFRA reviews recommend methodological improvements to better support the use of SFRA in clinical practice. This systematic review aimed to investigate the existing evidence of SFRA (discriminative capability, classification performance) and methodological factors (study design, samples, sensor features, and model validation) contributing to the risk of bias. The review was conducted according to recommended guidelines and 33 of 389 screened records were eligible for inclusion. Evidence of SFRA was identified: several sensor features and three classification models differed significantly between groups with different fall risk (mostly fallers/non-fallers). Moreover, classification performance corresponding the AUCs of at least 0.74 and/or accuracies of at least 84% were obtained from sensor features in six studies and from classification models in seven studies. Specificity was at least as high as sensitivity among studies reporting both values. Insufficient use of prospective design, small sample size, low in-sample inclusion of participants with elevated fall risk, high amounts and low degree of consensus in used features, and limited use of recommended model validation methods were identified in the included studies. Hence, future SFRA research should further reduce risk of bias by continuously improving methodology.

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  • 17.
    Kristoffersson, Annica
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Lindén, Maria
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    A Systematic Review of Wearable Sensors for Monitoring Physical Activity2022Ingår i: Sensors, E-ISSN 1424-8220, Vol. 22, nr 2, artikel-id 573Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    This article reviews the use of wearable sensors for the monitoring of physical activity (PA)for different purposes, including assessment of gait and balance, prevention and/or detection of falls,recognition of various PAs, conduction and assessment of rehabilitation exercises and monitoringof neurological disease progression. The article provides in-depth information on the retrievedarticles and discusses study shortcomings related to demographic factors, i.e., age, gender, healthyparticipants vs patients, and study conditions. It is well known that motion patterns change with ageand the onset of illnesses, and that the risk of falling increases with age. Yet, studies including olderpersons are rare. Gender distribution was not even provided in several studies, and others includedonly, or a majority of, men. Another shortcoming is that none of the studies were conducted inreal-life conditions. Hence, there is still important work to be done in order to increase the usefulnessof wearable sensors in these areas. The article highlights flaws in how studies based on previouslycollected datasets report on study samples and the data collected, which makes the validity andgeneralizability of those studies low. Exceptions exist, such as the promising recently reported opendataset FallAllD, wherein a longitudinal study with older adults is ongoing. 

  • 18.
    Kristoffersson, Annica
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Lindén, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    A Systematic Review on the Use of Wearable Body Sensors for Health Monitoring: A Qualitative Synthesis2020Ingår i: Sensors, E-ISSN 1424-8220, Vol. 20, nr 5, artikel-id 1502Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    The use of wearable body sensors for health monitoring is a quickly growing field with the potential of offering a reliable means for clinical and remote health management. This includes both real-time monitoring and health trend monitoring with the aim to detect/predict health deterioration and also to act as a prevention tool. The aim of this systematic review was to provide a qualitative synthesis of studies using wearable body sensors for health monitoring. The synthesis and analysis have pointed out a number of shortcomings in prior research. Major shortcomings are demonstrated by the majority of the studies adopting an observational research design, too small sample sizes, poorly presented, and/or non-representative participant demographics (i.e., age, gender, patient/healthy). These aspects need to be considered in future research work.

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  • 19.
    Kunnappilly, Ashalatha
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Marinescu, R.
    Bombardier Transportation, Västerås, Sweden.
    Seceleanu, Cristina
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    A Model-Checking-Based Framework for Analyzing Ambient Assisted Living Solutions2019Ingår i: Sensors, E-ISSN 1424-8220, Vol. 19, nr 22Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Since modern ambient assisted living solutions integrate a multitude of assisted-living functionalities, out of which some are safety critical, it is desirable that these systems are analyzed at their design stage to detect possible errors. To achieve this, one needs suitable architectures that support the seamless design of the integrated assisted-living functions, as well as capabilities for the formal modeling and analysis of the architecture. In this paper, we attempt to address this need, by proposing a generic integrated ambient assisted living system architecture, consisting of sensors, data collection, local and cloud processing schemes, and an intelligent decision support system, which can be easily extended to suit specific architecture categories. Our solution is customizable, therefore, we show three instantiations of the generic model, as simple, intermediate, and complex configurations, respectively, and show how to analyze the first and third categories by model checking. Our approach starts by specifying the architecture, using an architecture description language, in our case, the Architecture Analysis and Design Language, which can also account for the probabilistic behavior of such systems, and captures the possibility of component failure. To enable formal analysis, we describe the semantics of the simple and complex architectures within the framework of timed automata. We show that the simple architecture is amenable to exhaustive model checking by employing the UPPAAL tool, whereas for the complex architecture we resort to statistical model checking for scalability reasons. In this case, we apply the statistical extension of UPPAAL, namely UPPAAL SMC. Our work paves the way for the development of formally assured future ambient assisted living solutions.

  • 20.
    Köckemann, U.
    et al.
    Örebro University, Örebro, 70182, Sweden.
    Alirezaie, M.
    Örebro University, Örebro, 70182, Sweden.
    Renoux, J.
    Örebro University, Örebro, 70182, Sweden.
    Tsiftes, N.
    RISE SICS, RISE Research Institutes of Sweden, Stockholm, Sweden.
    Ahmed, Mobyen Uddin
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Morberg, Daniel
    Mälardalens högskola.
    Lindén, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Loutfi, A.
    Örebro University, Örebro, 70182, Sweden.
    Open-source data collection and data sets for activity recognition in smart homes2020Ingår i: Sensors, E-ISSN 1424-8220, Vol. 20, nr 3, artikel-id 879Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As research in smart homes and activity recognition is increasing, it is of ever increasing importance to have benchmarks systems and data upon which researchers can compare methods. While synthetic data can be useful for certain method developments, real data sets that are open and shared are equally as important. This paper presents the E-care@home system, its installation in a real home setting, and a series of data sets that were collected using the E-care@home system. Our first contribution, the E-care@home system, is a collection of software modules for data collection, labeling, and various reasoning tasks such as activity recognition, person counting, and configuration planning. It supports a heterogeneous set of sensors that can be extended easily and connects collected sensor data to higher-level Artificial Intelligence (AI) reasoning modules. Our second contribution is a series of open data sets which can be used to recognize activities of daily living. In addition to these data sets, we describe the technical infrastructure that we have developed to collect the data and the physical environment. Each data set is annotated with ground-truth information, making it relevant for researchers interested in benchmarking different algorithms for activity recognition.

  • 21.
    Lavassani, Mehrzad
    et al.
    Mid Sweden University, Sweden.
    Forsström, Stefan
    Mid Sweden University, Sweden.
    Jennehag, Ulf
    Mid Sweden University, Sweden.
    Zhang, Tingting
    Mid Sweden University, Sweden.
    Combining Fog Computing with Sensor Mote Machine Learning for Industrial IoT2018Ingår i: Sensors, E-ISSN 1424-8220, Vol. 18, nr 5, artikel-id 1532Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Digitalization is a global trend becoming ever more important to our connected and sustainable society. This trend also affects industry where the Industrial Internet of Things is an important part, and there is a need to conserve spectrum as well as energy when communicating data to a fog or cloud back-end system. In this paper we investigate the benefits of fog computing by proposing a novel distributed learning model on the sensor device and simulating the data stream in the fog, instead of transmitting all raw sensor values to the cloud back-end. To save energy and to communicate as few packets as possible, the updated parameters of the learned model at the sensor device are communicated in longer time intervals to a fog computing system. The proposed framework is implemented and tested in a real world testbed in order to make quantitative measurements and evaluate the system. Our results show that the proposed model can achieve a 98% decrease in the number of packets sent over the wireless link, and the fog node can still simulate the data stream with an acceptable accuracy of 97%. We also observe an end-to-end delay of 180 ms in our proposed three-layer framework. Hence, the framework shows that a combination of fog and cloud computing with a distributed data modeling at the sensor device for wireless sensor networks can be beneficial for Industrial Internet of Things applications.

  • 22.
    Li, Ning
    et al.
    Universidad Politecnica de Madrid, Madrid, Spain .
    Cürüklü, Baran
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Bastos, Joaquim
    Instituto de Telecomunicacoes, Lisboa, Portugal .
    Sucasas, Victor
    Universidade de Aveiro, Aveiro, Portugal .
    Fernandez, Jose Antonio Sanchez
    Universidad Politecnica de Madrid, Madrid, Spain .
    Rodriguez, Jonathan
    Campus Universitário de Santiago, Lisboa, Portugal .
    A probabilistic and highly efficient topology control algorithm for underwater cooperating AUV networks2017Ingår i: Sensors, E-ISSN 1424-8220, Vol. 17, nr 5, artikel-id 1022Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of the Smart and Networking Underwater Robots in Cooperation Meshes (SWARMs) project is to make autonomous underwater vehicles (AUVs), remote operated vehicles (ROVs) and unmanned surface vehicles (USVs) more accessible and useful. To achieve cooperation and communication between different AUVs, these must be able to exchange messages, so an efficient and reliable communication network is necessary for SWARMs. In order to provide an efficient and reliable communication network for mission execution, one of the important and necessary issues is the topology control of the network of AUVs that are cooperating underwater. However, due to the specific properties of an underwater AUV cooperation network, such as the high mobility of AUVs, large transmission delays, low bandwidth, etc., the traditional topology control algorithms primarily designed for terrestrial wireless sensor networks cannot be used directly in the underwater environment. Moreover, these algorithms, in which the nodes adjust their transmission power once the current transmission power does not equal an optimal one, are costly in an underwater cooperating AUV network. Considering these facts, in this paper, we propose a Probabilistic Topology Control (PTC) algorithm for an underwater cooperating AUV network. In PTC, when the transmission power of an AUV is not equal to the optimal transmission power, then whether the transmission power needs to be adjusted or not will be determined based on the AUV’s parameters. Each AUV determines their own transmission power adjustment probability based on the parameter deviations. The larger the deviation, the higher the transmission power adjustment probability is, and vice versa. For evaluating the performance of PTC, we combine the PTC algorithm with the Fuzzy logic Topology Control (FTC) algorithm and compare the performance of these two algorithms. The simulation results have demonstrated that the PTC is efficient at reducing the transmission power adjustment ratio while improving the network performance.

  • 23.
    Ljungblad, Jonas
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Hök Instrument AB, Sweden.
    Hök, Bertil
    Hök Instrument AB, Sweden.
    Ekström, Mikael
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Development and Evaluation of Algorithms for Breath Alcohol Screening2016Ingår i: Sensors, E-ISSN 1424-8220, Vol. 16, nr 4, artikel-id 469Artikel i tidskrift (Refereegranskat)
    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.

  • 24.
    Memedi, Mevludin
    et al.
    Dalarna University.
    Khan, Taha
    Mälardalens högskola, Akademin för innovation, design och teknik, Innovation och produktrealisering.
    Grenholm, Peter
    Uppsala University.
    Westin, Jerker
    Dalarna University.
    Automatic and Objective Assessment of Alternating Tapping Performance in Parkinson’s Disease2013Ingår i: Sensors, E-ISSN 1424-8220, Vol. 13, nr 12, s. 16965-16984Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents the development and evaluation of a method for enabling quantitative and automatic scoring of alternating tapping performance of patients with Parkinson’s disease (PD). Ten healthy elderly subjects and 95 patients in different clinical stages of PD have utilized a touch-pad handheld computer to perform alternate tapping tests in their home environments. First, a neurologist used a web-based system to visually assess impairments in four tapping dimensions (‘speed’, ‘accuracy’, ‘fatigue’ and ‘arrhythmia’) and a global tapping severity (GTS). Second, tapping signals were processed with time series analysis and statistical methods to derive 24 quantitative parameters. Third, principal component analysis was used to reduce the dimensions of these parameters and to obtain scores for the four dimensions. Finally, a logistic regression classifier was trained using a 10-fold stratified cross-validation to map the reduced parameters to the corresponding visually assessed GTS scores. Results showed that the computed scores correlated well to visually assessed scores and were significantly different across Unified Parkinson’s Disease Rating Scale scores of upper limb motor performance. In addition, they had good internal consistency, had good ability to discriminate between healthy elderly and patients in different disease stages, had good sensitivity to treatment interventions and could reflect the natural disease progression over time. In conclusion, the automatic method can be useful to objectively assess the tapping performance of PD patients and can be included in telemedicine tools for remote monitoring of tapping.

  • 25.
    Mählkvist, Simon
    et al.
    Mälardalens universitet, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Ejenstam, Jesper
    Kanthal AB, S-73427 Hallstahammar, Sweden..
    Kyprianidis, Konstantinos
    Mälardalens universitet, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Cost-Sensitive Decision Support for Industrial Batch Processes2023Ingår i: Sensors, E-ISSN 1424-8220, Vol. 23, nr 23, artikel-id 9464Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, cost-sensitive decision support was developed. Using Batch Data Analytics (BDA) methods of the batch data structure and feature accommodation, the batch process property and sensor data can be accommodated. The batch data structure organises the batch processes' data, and the feature accommodation approach derives statistics from the time series, consequently aligning the time series with the other features. Three machine learning classifiers were implemented for comparison: Logistic Regression (LR), Random Forest Classifier (RFC), and Support Vector Machine (SVM). It is possible to filter out the low-probability predictions by leveraging the classifiers' probability estimations. Consequently, the decision support has a trade-off between accuracy and coverage. Cost-sensitive learning was used to implement a cost matrix, which further aggregates the accuracy-coverage trade into cost metrics. Also, two scenarios were implemented for accommodating out-of-coverage batches. The batch is discarded in one scenario, and the other is processed. The Random Forest classifier was shown to outperform the other classifiers and, compared to the baseline scenario, had a relative cost of 26%. This synergy of methods provides cost-aware decision support for analysing the intricate workings of a multiprocess batch data system.

  • 26.
    Pathi, Sai Krishna
    et al.
    Örebro University, Sweden.
    Kiselev, Andrey
    Örebro University, Sweden.
    Kristoffersson, Annica
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Repsilber, Dirk
    Örebro University, Sweden.
    Loutfi, Amy
    Örebro University, Sweden.
    A Novel Method for Estimating Distances from a Robot to Humans Using Egocentric RGB Camera2019Ingår i: Sensors, E-ISSN 1424-8220, Vol. 19, nr 14, artikel-id E3142Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Estimating distances between people and robots plays a crucial role in understanding social Human-Robot Interaction (HRI) from an egocentric view. It is a key step if robots should engage in social interactions, and to collaborate with people as part of human-robot teams. For distance estimation between a person and a robot, different sensors can be employed, and the number of challenges to be addressed by the distance estimation methods rise with the simplicity of the technology of a sensor. In the case of estimating distances using individual images from a single camera in a egocentric position, it is often required that individuals in the scene are facing the camera, do not occlude each other, and are fairly visible so specific facial or body features can be identified. In this paper, we propose a novel method for estimating distances between a robot and people using single images from a single egocentric camera. The method is based on previously proven 2D pose estimation, which allows partial occlusions, cluttered background, and relatively low resolution. The method estimates distance with respect to the camera based on the Euclidean distance between ear and torso of people in the image plane. Ear and torso characteristic points has been selected based on their relatively high visibility regardless of a person orientation and a certain degree of uniformity with regard to the age and gender. Experimental validation demonstrates effectiveness of the proposed method.

  • 27.
    Rabet, Iliar
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Innovation och produktrealisering.
    Fotouhi, Hossein
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Alves, M.
    School of Engineering (ISEP/IPP), Politécnico do Porto, 4249-015 Porto, Portugal.
    Vahabi, Maryam
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Björkman, Mats
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    ACTOR: Adaptive Control of Transmission Power in RPL2024Ingår i: Sensors, E-ISSN 1424-8220, Vol. 24, nr 7, artikel-id 2330Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    RPL-Routing Protocol for Low-Power and Lossy Networks (usually pronounced "ripple")-is the de facto standard for IoT networks. However, it neglects to exploit IoT devices' full capacity to optimize their transmission power, mainly because it is quite challenging to do so in parallel with the routing strategy, given the dynamic nature of wireless links and the typically constrained resources of IoT devices. Adapting the transmission power requires dynamically assessing many parameters, such as the probability of packet collisions, energy consumption, the number of hops, and interference. This paper introduces Adaptive Control of Transmission Power for RPL (ACTOR) for the dynamic optimization of transmission power. ACTOR aims to improve throughput in dense networks by passively exploring different transmission power levels. The classic solutions of bandit theory, including the Upper Confidence Bound (UCB) and Discounted UCB, accelerate the convergence of the exploration and guarantee its optimality. ACTOR is also enhanced via mechanisms to blacklist undesirable transmission power levels and stabilize the topology of parent-child negotiations. The results of the experiments conducted on our 40-node, 12-node testbed demonstrate that ACTOR achieves a higher packet delivery ratio by almost 20%, reduces the transmission power of nodes by up to 10 dBm, and maintains a stable topology with significantly fewer parent switches compared to the standard RPL and the selected benchmarks. These findings are consistent with simulations conducted across 7 different scenarios, where improvements in end-to-end delay, packet delivery, and energy consumption were observed by up to 50%.

  • 28.
    Rahman, Hamidur
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Ahmed, Mobyen Uddin
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Barua, Shaibal
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Funk, Peter
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Begum, Shahina
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Vision-based driver’s cognitive load classification considering eye movement using machine learning and deep learning2021Ingår i: Sensors, E-ISSN 1424-8220, Vol. 21, nr 23, artikel-id 8019Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Due to the advancement of science and technology, modern cars are highly technical, more activity occurs inside the car and driving is faster; however, statistics show that the number of road fatalities have increased in recent years because of drivers’ unsafe behaviors. Therefore, to make the traffic environment safe it is important to keep the driver alert and awake both in human and autonomous driving cars. A driver’s cognitive load is considered a good indication of alertness, but determining cognitive load is challenging and the acceptance of wire sensor solutions are not preferred in real-world driving scenarios. The recent development of a non-contact approach through image processing and decreasing hardware prices enables new solutions and there are several interesting features related to the driver’s eyes that are currently explored in research. This paper presents a vision-based method to extract useful parameters from a driver’s eye movement signals and manual feature extraction based on domain knowledge, as well as automatic feature extraction using deep learning architectures. Five machine learning models and three deep learning architectures are developed to classify a driver’s cognitive load. The results show that the highest classification accuracy achieved is 92% by the support vector machine model with linear kernel function and 91% by the convolutional neural networks model. This non-contact technology can be a potential contributor in advanced driver assistive systems. 

  • 29. Rashkovska, A.
    et al.
    Depolli, M.
    Tomasic, Ivan
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Avbelj, V.
    Trobec, R.
    Medical-grade ECG sensor for long-term monitoring2020Ingår i: Sensors, E-ISSN 1424-8220, Vol. 20, nr 6, artikel-id 1695Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The recent trend in electrocardiogram (ECG) device development is towards wireless body sensors applied for patient monitoring. The ultimate goal is to develop a multi-functional body sensor that will provide synchronized vital bio-signs of the monitored user. In this paper, we present an ECG sensor for long-term monitoring, which measures the surface potential difference between proximal electrodes near the heart, called differential ECG lead or differential lead, in short. The sensor has been certified as a class IIa medical device and is available on the market under the trademark Savvy ECG. An improvement from the user’s perspective—immediate access to the measured data—is also implemented into the design. With appropriate placement of the device on the chest, a very clear distinction of all electrocardiographic waves can be achieved, allowing for ECG recording of high quality, sufficient for medical analysis. Experimental results that elucidate the measurements from a differential lead regarding sensors’ position, the impact of artifacts, and potential diagnostic value, are shown. We demonstrate the sensors’ potential by presenting results from its various areas of application: medicine, sports, veterinary, and some new fields of investigation, like hearth rate variability biofeedback assessment and biometric authentication. 

  • 30.
    Rodríguez-Molina, J.
    et al.
    Centro de Investigación en Tecnologías Software y Sistemas Multimedia Para la Sostenibilidad—CITSEM, Madrid, Spain.
    Bilbao, S.
    TECNALIA, Derio, Bizkaia, Spain.
    Martínez, B.
    TECNALIA, Derio, Bizkaia, Spain.
    Frasheri, Mirgita
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Curuklu, Baran
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    An optimized, data distribution service-based solution for reliable data exchange among autonomous underwater vehicles2017Ingår i: Sensors, E-ISSN 1424-8220, Vol. 17, nr 8, artikel-id 1802Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Major challenges are presented when managing a large number of heterogeneous vehicles that have to communicate underwater in order to complete a global mission in a cooperative manner. In this kind of application domain, sending data through the environment presents issues that surpass the ones found in other overwater, distributed, cyber-physical systems (i.e., low bandwidth, unreliable transport medium, data representation and hardware high heterogeneity). This manuscript presents a Publish/Subscribe-based semantic middleware solution for unreliable scenarios and vehicle interoperability across cooperative and heterogeneous autonomous vehicles. The middleware relies on different iterations of the Data Distribution Service (DDS) software standard and their combined work between autonomous maritime vehicles and a control entity. It also uses several components with different functionalities deemed as mandatory for a semantic middleware architecture oriented to maritime operations (device and service registration, context awareness, access to the application layer) where other technologies are also interweaved with middleware (wireless communications, acoustic networks). Implementation details and test results, both in a laboratory and a deployment scenario, have been provided as a way to assess the quality of the system and its satisfactory performance. 

  • 31.
    Rodríguez-Molina, Jesús
    et al.
    Technical University of Madrid.
    Martínez-Ortega, José-Fernán
    Technical University of Madrid.
    Castillejo, Pedro
    Technical University of Madrid.
    Lopez, Lourdes
    Technical University of Madrid.
    Combining Wireless Sensor Networks and Semantic Middleware for an Internet of Things-Based Sportsman/Woman Monitoring Application2013Ingår i: Sensors, E-ISSN 1424-8220, Vol. 13, nr 2, s. 1787-1835Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wireless Sensor Networks (WSNs) are spearheading the efforts taken to build and deploy systems aiming to accomplish the ultimate objectives of the Internet of Things. Due to the sensors WSNs nodes are provided with, and to their ubiquity and pervasive capabilities, these networks become extremely suitable for many applications that so-called conventional cabled or wireless networks are unable to handle. One of these still underdeveloped applications is monitoring physical parameters on a person. This is an especially interesting application regarding their age or activity, for any detected hazardous parameter can be notified not only to the monitored person as a warning, but also to any third party that may be helpful under critical circumstances, such as relatives or healthcare centers. We propose a system built to monitor a sportsman/woman during a workout session or performing a sport-related indoor activity. Sensors have been deployed by means of several nodes acting as the nodes of a WSN, along with a semantic middleware development used for hardware complexity abstraction purposes. The data extracted from the environment, combined with the information obtained from the user, will compose the basis of the services that can be obtained.

  • 32.
    Salilew, Waleligne Molla
    et al.
    Mechanical Engineering Department, Seri Iskandar 32610, Universiti Teknologi PETRONAS, Malaysia.
    Abdul Karim, Zainal Ambri
    Mechanical Engineering Department, Seri Iskandar 32610, Universiti Teknologi PETRONAS, Malaysia.
    Lemma, Tamiru Alemu
    Mechanical Engineering Department, Seri Iskandar 32610, Universiti Teknologi PETRONAS, Malaysia.
    Fentaye, Amare Desalegn
    Mälardalens universitet, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Kyprianidis, Konstantinos
    Mälardalens universitet, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Three Shaft Industrial Gas Turbine Transient Performance Analysis2023Ingår i: Sensors, E-ISSN 1424-8220, Vol. 23, nr 4Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The power demand from gas turbines in electrical grids is becoming more dynamic due to the rising demand for power generation from renewable energy sources. Therefore, including the transient data in the fault diagnostic process is important when the steady-state data are limited and if some component faults are more observable in the transient condition than in the steady-state condition. This study analyses the transient behaviour of a three-shaft industrial gas turbine engine in clean and degraded conditions with consideration of the secondary air system and variable inlet guide vane effects. Different gas path faults are simulated to demonstrate how magnified the transient measurement deviations are compared with the steady-state measurement deviations. The results show that some of the key measurement deviations are considerably higher in the transient mode than in the steady state. This confirms the importance of considering transient measurements for early fault detection and more accurate diagnostic solutions.

  • 33.
    Salilew, Waleligne Molla
    et al.
    Univ Teknol Petronas, Mech Engn Dept, Bandar Seri Iskandar 32610, Perak, Malaysia..
    Karim, Zainal Ambri Abdul
    Univ Teknol Petronas, Ctr Automot Res & Elect Mobil CAREM, Bandar Seri Iskandar 32610, Perak, Malaysia..
    Lemma, Tamiru Alemu
    Univ Teknol Petronas, Mech Engn Dept, Bandar Seri Iskandar 32610, Perak, Malaysia..
    Fentaye, Amare Desalegn
    Mälardalens universitet, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Kyprianidis, Konstantinos
    Mälardalens universitet, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    The Effect of Physical Faults on a Three-Shaft Gas Turbine Performance at Full- and Part-Load Operation2022Ingår i: Sensors, E-ISSN 1424-8220, Vol. 22, nr 19, artikel-id 7150Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A gas path analysis approach of dynamic modelling was used to examine the gas turbine performance. This study presents an investigation of the effect of physical faults on the performance of a three-shaft gas turbine at full-load and part-load operation. A nonlinear steady state performance model was developed and validated. The datasheet from the engine manufacturer was used to gather the input and validation data. Some engineering judgement and optimization were used. Following validation of the engine performance model with the engine manufacturer data using physical fault and component health parameter relationships, physical faults were implanted into the performance model to evaluate the performance characteristics of the gas turbine at degradation state at full- and part-load operation. The impact of erosion and fouling on the gas turbine output parameters, component measurement parameters, and the impact of degraded components on another primary component of the engine have been investigated. The simulation results show that the deviation in the output parameters and component isentropic efficiency due to compressor fouling and erosion is linear with the load variation, but it is almost nonlinear for the downstream components. The results are discussed following the plots.

  • 34.
    Schwartz, C.
    et al.
    KTH Royal Institute of Technology, Sweden.
    Sander, I.
    KTH Royal Institute of Technology, Sweden.
    Bruhn, Fredrik
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system. Unibap AB, Sweden.
    Persson, M.
    Unibap AB, Sweden.
    Ekblad, J.
    Saab AB, Stockholm, Sweden.
    Fuglesang, C.
    KTH Royal Institute of Technology, Sweden.
    Satellite Image Compression Guided by Regions of Interest2023Ingår i: Sensors, E-ISSN 1424-8220, Vol. 23, nr 2, artikel-id 730Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Small satellites empower different applications for an affordable price. By dealing with a limited capacity for using instruments with high power consumption or high data-rate requirements, small satellite missions usually focus on specific monitoring and observation tasks. Considering that multispectral and hyperspectral sensors generate a significant amount of data subjected to communication channel impairments, bandwidth constraint is an important challenge in data transmission. That issue is addressed mainly by source and channel coding techniques aiming at an effective transmission. This paper targets a significant further bandwidth reduction by proposing an on-the-fly analysis on the satellite to decide which information is effectively useful before coding and transmitting. The images are tiled and classified using a set of detection algorithms after defining the least relevant content for general remote sensing applications. The methodology makes use of the red-band, green-band, blue-band, and near-infrared-band measurements to perform the classification of the content by managing a cloud detection algorithm, a change detection algorithm, and a vessel detection algorithm. Experiments for a set of typical scenarios of summer and winter days in Stockholm, Sweden, were conducted, and the results show that non-important content can be identified and discarded without compromising the predefined useful information for water and dry-land regions. For the evaluated images, only 22.3% of the information would need to be transmitted to the ground station to ensure the acquisition of all the important content, which illustrates the merits of the proposed method. Furthermore, the embedded platform’s constraints regarding processing time were analyzed by running the detection algorithms on Unibap’s iX10-100 space cloud platform.

  • 35.
    Tahmasebi, S.
    et al.
    Department of Computer Engineering, Sharif University of Technology, Tehran, Iran.
    Safi, M.
    Shariaty Technical College, Technical and Vocational University, Tehran, Iran.
    Zolfi, S.
    School of Computer Engineering, University of Science and Technology, Tehran, Iran.
    Maghsoudi, M. R.
    Zand Institute of Higher Education, Shiraz, Iran.
    Faragardi, H. R.
    KTH Royal Institute of Technology.
    Fotouhi, Hossein
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Cuckoo-PC: An evolutionary synchronization-aware placement of SDN controllers for optimizing the network performance in WSNs2020Ingår i: Sensors, E-ISSN 1424-8220, Vol. 20, nr 11, s. 1-19, artikel-id 3231Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Due to reliability and performance considerations, employing multiple software-defined networking (SDN) controllers is known as a promising technique in Wireless Sensor Networks (WSNs). Nevertheless, employing multiple controllers increases the inter-controller synchronization overhead. Therefore, optimal placement of SDN controllers to optimize the performance of a WSN, subject to the maximum number of controllers, determined based on the synchronization overhead, is a challenging research problem. In this paper, we first formulate this research problem as an optimization problem, then to address the optimization problem, we propose the Cuckoo Placement of Controllers (Cuckoo-PC) algorithm. Cuckoo-PC works based on the Cuckoo optimization algorithm which is a meta-heuristic algorithm inspired by nature. This algorithm seeks to find the global optimum by imitating brood parasitism of some cuckoo species. To evaluate the performance of Cuckoo-PC, we compare it against a couple of state-of-the-art methods, namely Simulated Annealing (SA) and Quantum Annealing (QA). The experiments demonstrate that Cuckoo-PC outperforms both SA and QA in terms of the network performance by lowering the average distance between sensors and controllers up to 13% and 9%, respectively. Comparing our method against Integer Linear Programming (ILP) reveals that Cuckoo-PC achieves approximately similar results (less than 1% deviation) in a noticeably shorter time. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

  • 36.
    Zolfaghari, Samaneh
    et al.
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Kristoffersson, Annica
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Folke, Mia
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Lindén, Maria
    Mälardalens universitet, Akademin för innovation, design och teknik, Inbyggda system.
    Riboni, Daniele
    Department of Mathematics and Computer Science, University of Cagliari, 09124 Cagliari, Italy.
    Unobtrusive Cognitive Assessment in Smart-Homes: Leveraging Visual Encoding and Synthetic Movement Traces Data Mining2024Ingår i: Sensors, E-ISSN 1424-8220, Vol. 24, nr 5, s. 1381-1381Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The ubiquity of sensors in smart-homes facilitates the support of independent living for older adults and enables cognitive assessment. Notably, there has been a growing interest in utilizing movement traces for identifying signs of cognitive impairment in recent years. In this study, we introduce an innovative approach to identify abnormal indoor movement patterns that may signal cognitive decline. This is achieved through the non-intrusive integration of smart-home sensors, including passive infrared sensors and sensors embedded in everyday objects. The methodology involves visualizing user locomotion traces and discerning interactions with objects on a floor plan representation of the smart-home, and employing different image descriptor features designed for image analysis tasks and synthetic minority oversampling techniques to enhance the methodology. This approach distinguishes itself by its flexibility in effortlessly incorporating additional features through sensor data. A comprehensive analysis, conducted with a substantial dataset obtained from a real smart-home, involving 99 seniors, including those with cognitive diseases, reveals the effectiveness of the proposed functional prototype of the system architecture. The results validate the system’s efficacy in accurately discerning the cognitive status of seniors, achieving a macro-averaged F1-score of 72.22% for the two targeted categories: cognitively healthy and people with dementia. Furthermore, through experimental comparison, our system demonstrates superior performance compared with state-of-the-art methods.

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