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  • 1.
    Abdullah, Saad
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Kanwal, Kehkashan
    Mälardalen University, School of Innovation, Design and Engineering.
    Hafid, A.
    Ziauddin University, Department of Electrical Engineering, Karachi, Pakistan.
    Difallah, S.
    University of Science and Technology Houari Boumediene, Instrumentation Laboratory, Algiers, Algeria.
    Low-cost BLE based intravenous monitoring and control infusion system2023In: Int. Conf. Adv. Electron., Control Commun. Syst., ICAECCS, Institute of Electrical and Electronics Engineers Inc. , 2023Conference paper (Refereed)
    Abstract [en]

    Administering the medications and fluids intravenously is a frequent practice in modern medical procedures, which plays a vital role in the treatment of certain acute conditions which require immediate action by drugs or fluids. This paper covers the design of a low-cost, wireless drip monitoring system for use in the hospital environment. The device is equipped with the Bluetooth low energy based battery-operated microcontroller, an infrared based drops counting system and a digital servo motor to control the drip flow rate, and it is attached to an existing intravenous stand. A LabView graphical user interface has also been developed to provide sets of input to the system to calculate the desired drip rate and the amount of pressure that digital servo motor must apply to achieve it. The system shows an average accuracy of 96% when compared with the measured and calculated values. This allows accurate computation of the level of the drip.

  • 2.
    Antonic, Nemanja
    et al.
    Mälardalen University.
    Khalid, A. H.
    Mälardalen University.
    Hamila, M. E.
    Mälardalen University.
    Xiong, Ning
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Online Tuning of PID Controllers Based on Membrane Neural Computing2023In: Lecture Notes on Data Engineering and Communications Technologies, Springer Science and Business Media Deutschland GmbH , 2023, Vol. 153, p. 455-464Chapter in book (Other academic)
    Abstract [en]

    PID controllers are still popular in a wide range of engineering practices due to their simplicity and robustness. Traditional design of a PID controller needs manual setting of its parameters in advance. This paper proposes a new method for online tuning of PID controllers based on hybridized neural membrane computing. A neural network is employed to adaptively determine the proper values of the PID parameters in terms of evolving situations/stages in the control process. Further the learning of the neural network is performed based on a membrane algorithm, which is used to locate the weights of the network to optimize the control performance. The effectiveness of the proposed method has been demonstrated by the preliminary results from simulation tests.

  • 3.
    Avelin, Anders
    et al.
    Mälardalen University, School of Business, Society and Engineering.
    Widarsson, Björn
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Lilja, Reijo
    VTT, Espoo, Finland.
    Time based data reconciliation and decision support for a CFB boiler2009In: IFAC Proceedings Volumes (IFAC-PapersOnline), 2009 / [ed] Yrjö Majanne, Tampere: Tampere University Press , 2009, p. 338-343Conference paper (Refereed)
    Abstract [en]

    This paper covers a method for operator decision support, where physical simulation models are used to connect different physical variables to each other. By comparing energy and material balances for a larger process area inconsistencies in single process parts and sensor measurements can be detected, by following the development between single measurements and values predicted from the simulations. This information then can be used as input to e.g. a BN, Bayesian Network, for decision support. The application has been for a CFB boiler at Mälarenergi AB. The simulators have been made in Modelica respectively a more advanced model in APROS.

  • 4.
    Aziz, Victor
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Brouillette, Hanna
    Mälardalen University, School of Business, Society and Engineering.
    OPTIMIZING CYCLE TIME OF ELECTRIC AUTONOMOUS HAULERS:A CASE STUDY IN MINING APPLICATIONS2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Traditionally, the fastest method to travel between two points is perceived as driving at maximumspeed. However, when the vehicle in question is an electric vehicle, the additional time requiredfor charging introduces another variable that can be optimized alongside driving time. This studyexplores the optimization of total time - including both driving and charging - for an autonomouselectric hauler, the TA15, developed by Volvo Construction Equipment, operating within a miningsite scenario.The issue is framed as an optimal control problem, building upon various formulations from relatedwork. An objective function is created, with a weighting factor applied to balance the prioritizationof driving time minimization and charging time minimization. It is discovered that this weightingfactor can be calculated as the inverse of the charging power.The problem is solved using a method called direct collocation, finding the optimal solutions fordriving time minimization only and total time optimization. The results reveal that the solutionfor total time optimization mirrors that of driving time minimization when less energy is neededand a high charging rate is available. However, when the charging rate is low relative to the energyneeded, the optimal solution is no longer simply driving at maximum speed. Instead, adopting aneco-driving approach yields a more time-efficient solution.The models used in this study are based on related work, and the results demonstrate that optimalsolutions exist beyond simply driving at full speed. As the comparison is made using the samemodel, any errors exist in both cases. Consequently, the existence of alternative optimal solutionswithin these models indicates the potential for similar solutions in more accurate models. However,this hypothesis still requires further validation.

    Download full text (pdf)
    OPTIMIZING CYCLE TIME OF ELECTRIC AUTONOMOUS HAULERS
  • 5.
    Aziz, Victor
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Brouillette, Hanna
    Mälardalen University, School of Business, Society and Engineering.
    OPTIMIZING CYCLE TIME OF ELECTRIC AUTONOMOUS HAULERS:A CASE STUDY IN MINING APPLICATIONS2023Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Traditionally, the fastest method to travel between two points is perceived as driving at maximumspeed. However, when the vehicle in question is an electric vehicle, the additional time requiredfor charging introduces another variable that can be optimized alongside driving time. This studyexplores the optimization of total time - including both driving and charging - for an autonomouselectric hauler, the TA15, developed by Volvo Construction Equipment, operating within a miningsite scenario.The issue is framed as an optimal control problem, building upon various formulations from relatedwork. An objective function is created, with a weighting factor applied to balance the prioritizationof driving time minimization and charging time minimization. It is discovered that this weightingfactor can be calculated as the inverse of the charging power.The problem is solved using a method called direct collocation, finding the optimal solutions fordriving time minimization only and total time optimization. The results reveal that the solutionfor total time optimization mirrors that of driving time minimization when less energy is neededand a high charging rate is available. However, when the charging rate is low relative to the energyneeded, the optimal solution is no longer simply driving at maximum speed. Instead, adopting aneco-driving approach yields a more time-efficient solution.The models used in this study are based on related work, and the results demonstrate that optimalsolutions exist beyond simply driving at full speed. As the comparison is made using the samemodel, any errors exist in both cases. Consequently, the existence of alternative optimal solutionswithin these models indicates the potential for similar solutions in more accurate models. However,this hypothesis still requires further validation.

    Download (pdf)
    attachment
  • 6.
    Beckman, Erik
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Harenius, Linus
    Mälardalen University, School of Innovation, Design and Engineering.
    Monitored Neural Networks for Autonomous Articulated Machines2020Independent thesis Advanced level (degree of Master (Two Years)), 300 HE creditsStudent thesis
    Abstract [en]

    Being able to safely control autonomous heavy machinery is of uttermost importance for the conversion of traditional machines to autonomous machines. With the continuous growth of autonomous vehicles around the globe, an increasing effort has been put into certifying autonomous vehicles in terms of reliability and safety. In this thesis, we will investigate the problem with a deviation from the planned path for an autonomous hauler from Volvo Construction Equipment. The autonomous hauler has an error within the kinematic model, the feed-forward curvature-steering controller, due to a slip-effect that comes with the third wheel-axle. The deviation can especially be seen in sharp curves, where the deviation needs to be decreased in order to make the autonomous hauler more dependable and achieve an increased accuracy when following any given path. The aim of the thesis is to develop a fully functional Artificial Neural Network that has a new steering angle as output. The hypothesis for this thesis is to use an ANN to mimic the steering of a human driver, since a real driver compensates for the slipping behavior; both because the operator knows where on the road the machine is and also in the way that a human thinks many steps ahead whilst driving. This proposed ANN will have a monitor function which ensures that the steering angle command operates within its boundaries. Hence this thesis implies that it is indeed possible to ensure that the ANN performs reliably with the help of a monitor function in a simulated environment and can thus be used in dependable systems.

    Download full text (pdf)
    MonitoredANN_forAAH
  • 7.
    Bini, E.
    et al.
    University of Turin, Italy.
    Papadopoulos, Alessandro
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Higgins, J.
    University of Virginia, USA.
    Bezzo, N.
    University of Virginia, USA.
    Optimal Reference Tracking for Sampled-Data Control Systems2022In: Proceedings of the IEEE Conference on Decision and Control, Institute of Electrical and Electronics Engineers Inc. , 2022, p. 7141-7148Conference paper (Refereed)
    Abstract [en]

    It is a standard engineering practice to design feedback-based control to have a system follow a given trajectory. While the trajectory is continuous-time, the sequence of references is varied at discrete times as it is normally computed by digital systems.In this work, we propose a method to determine the optimal discrete-time references to be applied over a time window of a given duration. The optimality criterion is the minimization of a weighted L2 norm between the achieved trajectory and a given target trajectory which is desired to be followed. The proposed method is then assessed over different simulation results, analyzing the design parameters' effects, and over a UAV use case. The code to reproduce the results is publicly available.

  • 8. Blanco, Angeles
    et al.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Kappen, Johannes
    Manninen, Jussi
    Negro, Carlos
    Rittala, Risto
    Chapter 12: Modelling and simulation in the Pulp and Paper Industry: Current state and future perspectives2006In: Handbook of Control Room Design and Ergonomics: A Perspective for the Future / [ed] Toni Ivergård and Brian Hunt, Taylor & Francis Group, 2006, 2nd, p. 311-326Chapter in book (Other academic)
  • 9.
    Brickman, Staffan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Andersson, Peter
    Mälardalen University, School of Innovation, Design and Engineering.
    Improving the accuracy of an industrial robotic arm using iterative learning control with data fusion of motor angles and imu sensors2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The estimated position of an industrial robot’s end-effector is crucial for its performance. Contemporary methods for doing the estimation is limited in certain aspects, and alternative methods are in high demand. This work builds on a method previously introduced where an Inertial Measurement Unit (IMU) device is combined with the robot’s system via sensor fusion. The IMU must be calibrated before its signal is used in sensor fusion and this work implements and builds on current cutting-edge methods for calibration. Sensor fusion is a crucial part of the method and here a complementary filter is used. The finished estimation is then used with Iterative Learning Control (ILC) to investigate if the accuracy can be further improved and also test its viability. Results from ILC show that the IMU can indeed be used to estimate the end-effector's trajectory but that sensor fusion is mandatory. Further research could be done to allow the estimation to be done online instead of offline and ILC could be tested more extensively.

    Download full text (pdf)
    fulltext
  • 10.
    Dahlquist, Erik
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Hunt, Brian
    Ivergård, Toni
    Chapter 8: Industrial Applications and Case Studies2009In: Handbook of Control Room Design and Ergonomics: A Perspective for the Future / [ed] Toni Ivergård and Brian Hunt, Taylor & Francis Group, 2009, 2nd, p. 203-226Chapter in book (Other academic)
  • 11.
    Dahlquist, Erik
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Tomas-Aparicio, Elena
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Jansson, Johan
    SAPPI South Africa.
    On-line simulations for diagnostics and control2010In: International Control Systems 2010 Proceedings / [ed] Alf Isaksson, Stockholm: SPCI , 2010Conference paper (Refereed)
    Abstract [en]

    The main objective of this project is to develop an application where physical models of fibre lines are run in parallel to the real processes. This application can be useful as a diagnostic tool to detect faults and improve process operations. By running the simulation models continuously, feeding input data from the process data base at a pre-determined time interval, the simulation will show results from the “normal operations”. These simulation results are compared to the measured data and hence faults can be detected e.g. hang-ups in the digester and channelling. NIR-spectra lab measurements of the wood chips fed into the digester can as well be considered. This feature give us the possibility of correlating the quality of the obtained pulp to the raw material used, which can be of help when tuning the process parameters.

    In this paper results from the use of the application described above in several mills in South Africa and results from some preliminary tests in a mill in Sweden are presented. Moreover, the system structure for the interaction between the physical models designed in Modellica language and the real process data is described.

  • 12.
    Deivard, Johannes
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Johansson, Valentin
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Diagnostics Framework for Time-Critical Control Systems in Cloud-Fog Automation2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Evolving technology in wireless telecommunication, such as 5G, provides opportunities to utilize wireless communication more in an industrial setting where reliability and predictability are of great concern. More capable Industrial Internet of Things devices (IIoT) are, indeed, a catalyst for Industry 4.0. Still, before the IIoT devices can be deemed capable enough, a method to evaluate the IIoT systems unobtrusively—so that the evaluation does not affect the performance of the systems—must be established. This thesis aims to answer how the performance of a distributed control system can be unobtrusively evaluated, and also determine what the state-of-the-art is in latency measurements in distributed control systems. To answer the question, a novel diagnostics method for time-critical control systems in cloud-fog automation is proposed and extensively evaluated on real-life testbeds that use 5G, WiFi 6, and Ethernet in an edge-computing topology with real control systems. The feasibility of the proposed method was verified by experiments conducted with a diagnostics framework prototype developed in this thesis. In the proposed diagnostics framework, the controller application is monitored by a computing probe based on an extended Berkeley Packet Filter program. Network communication between the controller and control target is evaluated with a multi-channel Ethernet probe and custom-made software that computes several metrics related to the performance of the distributed system. The data from the unobtrusive probes are sent to a time-series database that is used for further analysis and real-time visualization in a graphical interface created with Grafana. The proposed diagnostics method together with the developed prototype can be used as a research infrastructure for future evaluations of distributed control systems.

    Download full text (pdf)
    cfa_diagnostics_framework
  • 13.
    Fiaschetti, Andrea
    et al.
    University of Rome La Sapienza, Italy.
    Lavorato, Francesco
    University of Rome La Sapienza, Italy.
    Suraci, Vincenzo
    University of Rome La Sapienza, Italy.
    Palo, Andi
    University of Rome La Sapienza, Italy.
    Taglialatela, Andrea
    TRS SpA, Italy.
    Morgagni, Andrea
    Elsag Datamat S.p.a., Italy.
    Baldelli, Renato
    Elsag Datamat S.p.a., Italy.
    Flammini, Francesco
    Ansaldo STS S.p.a., Italy.
    On the use of semantic technologies to model and control security, privacy and dependability in complex systems2011In: Computer Safety, Reliability, and Security: 30th International Conference, SAFECOMP 2011, Naples, Italy, September 19-22, 2011, Proceedings / [ed] Francesco Flammini, Sandro Bologna, Valeria Vittorini, Berlin, Heidelberg: Springer , 2011, p. 467-479Conference paper (Refereed)
    Abstract [en]

    In this paper a semantic approach is presented to model and control Security, Privacy and Dependability (SPD) in complex interconnected environment composed by heterogeneous Embedded Systems. Usually, only the individual properties are locally considered to obtain desired functionalities and this could result in sub-optimal solutions. With the use of modern semantic technologies (like OWL or reasoning engines) it is possible to model not only the individual parameters but also the relations between the different (and dynamically changing) parts of the systems, thus providing enriched knowledge and more useful information that could feed control algorithms. The model presented in this paper is based on the results obtained during the first phase of the pSHIELD project (conceived and lead by Finmeccanica) and it is focused on a concrete application coming from a critical scenario in railway environment: the monitoring of freight trains transporting hazardous material.

  • 14.
    Friebe, Anna
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Markovic, Filip
    Mälardalen University, School of Innovation, Design and Engineering, Innovation and Product Realisation. Max Planck Institute for Software Systems (MPI-SWS), Germany.
    Papadopoulos, Alessandro
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Continuous-Emission Markov Models for Real-Time Applications: Bounding Deadline Miss Probabilities2023In: Proc. IEEE Real Time Embedded Technol. Appl. Symp. RTAS, Institute of Electrical and Electronics Engineers Inc. , 2023, p. 14-26Conference paper (Refereed)
    Abstract [en]

    Probabilistic approaches have gained attention over the past decade, providing a modeling framework that enables less pessimistic analysis of real-time systems. Among the different proposed approaches, Markov chains have been shown effective for analyzing real-time systems, particularly in estimating the pending workload distribution and deadline miss probability. However, the state-of-the-art mainly considered discrete emission distributions without investigating the benefits of continuous ones. In this paper, we propose a method for analyzing the workload probability distribution and bounding the deadline miss probability for a task executing in a reservation-based server, where execution times are described by a Markov model with Gaussian emission distributions. The evaluation is performed for the timing behavior of a Kalman filter for Furuta pendulum control. Deadline miss probability bounds are derived with a workload accumulation scheme. The bounds are compared to 1) measured deadline miss ratios of tasks running under the Linux Constant Bandwidth Server with SCHED-DEADLINE, 2) estimates derived from a Markov Model with discrete-emission distributions (PROSIT), 3) simulation-based estimates, and 4) an estimate assuming independent execution times. The results suggest that the proposed method successfully upper bounds actual deadline miss probabilities. Compared to the discrete-emission counterpart, the computation time is independent of the range of the execution times under analysis, and resampling is not required.

  • 15.
    Gerdtman, Christer
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Bäcklund, Ylva
    Office for Science and Technology, Uppsala University, Uppsala, Sweden.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering.
    A gyro sensor based computer mouse with a USB interface: A technical aid for motor-disabled people2012In: Technology and disability, ISSN 1055-4181, Vol. 24, no 2, p. 117-127Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to develop an alternative computer mouse for disabled persons. The mouse developed is a flexible input device with a multi-click function, which can be attached to a selectable body part (eg head, arm, foot). The mouse has a MEMS-gyroscope as the motion sensor, which is both small and sensitive. A USB-interface with a HID-profile is used to make the installation easy, "plug & play", and to make it compatible for use on any modern computer, independent of the operating system (Windows, Linux, Mac etc.). The structure is modular to achieve a flexible functionality. The mouse has individually adapted click-functions with selectable click devices, in addition to which, it is possible to define individual settings of the mouse parameters. The functionality can be extended by adding further personal settings, thereby programming the mouse for individual optimal performance. The result is a reliable and useful computer mouse for people with disabilities. In the development process, 23 users have been interviewed, three of whom participated in a 6 month long-term test. The study shows that a computer mouse incorporating a MEMS-gyroscope is a good, flexible solution, providing a high performance technical aid with extremely good sensitivity at a modest cost.

  • 16.
    Gerdtman, Christer
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Bäcklund, Ylva
    Uppsala University.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering.
    Development of a Test Rig for MEMS-based Gyroscopic Motion Sensors in Human Applications2011In: IFMBE Proceedings,  Volume 34 IFMBE, 2011, 2011, p. 203-206Conference paper (Refereed)
    Abstract [en]

    This paper describes the development of a test rig for MEMS gyroscopes. The purpose of the test rig is testing and verification of various gyroscopes that are intended for human motion analysis. The test rig will be a tool to test functionality and help in the selection process of appropriate MEMS-gyroscopes. Human movement pattern differs from mechanical motion and thus puts specific demands on the test equipment and verification procedures. The main function of the test rig is to rotate the gyroscope and measure the precision in the sensor signal response in different situations. This includes detection of different movement patterns and performances in different environment conditions (e.g. temperature, vibrations, etc). Several components can be tested at the same time in the test rig. Among the things that can be evaluated is the performance of the components, comparisons between different individual components or batches, aging processes of components and verification of the component performance for comparison of the specifications from the manufacturer. There are several different pre-programmed test-programs available but the test rig can also be manually operated. The data from the tests are stored and can be analyzed and processed afterwards.

  • 17.
    Gerdtman, Christer
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Folke, Mia
    Mälardalen University, School of Innovation, Design and Engineering.
    Bexander, Catharina
    Hälsans hus.
    Brodd, Anita
    Mälardoktorerna HB.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering.
    Portable sensor system for rehabilitation of WAD patients2009In: Proceedings of the 6th International Workshop on Wearable, Micro, and Nano Technologies for Personalized Health: "Facing Future Healthcare Needs", IEEE , 2009, p. 65-68Conference paper (Refereed)
    Abstract [en]

    Whiplash Associated Disorders (WAD) are several remaining symptoms after an acceleration-/deceleration injury of the neck, often due to a road accident. Common symptoms are neck pain, headache, stiffness, loss of sensation, memory impairment and concentration difficulties. The whiplash-related injuries were estimated to cost Sweden more than SEK 4 billion 2005, the main part of these costs takes the form of compensation for loss of income, as a result of incapacity for work. The aim of this project has been to develop a training and rehabilitation system for patients suffering from WAD. The portable system is based on a 2-axis gyroscopic sensor with a computer interface. The sensor system is placed on the head of the patient and movements of the head are mirrored on the computer screen. The patient is supposed to follow a visible track on the screen. This enables interactive training facilities for patients, who can use the system unsupervised in their home environment.

  • 18.
    Gerdtman, Christer
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Lindén, Maria
    Mälardalen University, Department of Computer Science and Electronics.
    Development of a gyro sensor based computer mouse with USB interface interface as technical aid for disabled persons2005In: 3rd European Medical & Biological Engineering Conference (EMBEC’05), Vienna (Austria): Society for the Organization of the European Medical and Biological Engineering Conference EMBEC , 2005Conference paper (Refereed)
    Abstract [en]

    This paper describes the development of an alternative computer mouse for disabled persons. The mouse is an advanced technical aid for a large group of disabled (handicapped) persons, and can be placed on variuos suitable body parts. The mouse is module based and have many functions that enable a disabled persons to control a computer. It also allows the person to work efficent on the computer. The functions have been developed togehter with disabled persons and are based on their wishes and needs. Therfor it is not only a «head-mouse», it is an alternative mouse! The device is a gyro sensor based computer mouse and it operates by sensing the rotation of a body part. The disabled users appreciated the high sensitivity of the mouse and that it is easy to install and use, thanks the USB «plug&play» functionality. The mouse is a small and comfortable computer mouse that suits a various groups of disabled persons with different types of movement handicaps.

  • 19.
    Gu, Rong
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Moezkarimi, Zahra
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Sirjani, Marjan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Guess and Then Check: Controller Synthesis for Safe and Secure Cyber-Physical Systems2024In: Lecture Notes in Computer Science, Springer Science+Business Media B.V., 2024, p. 230-238Conference paper (Refereed)
    Abstract [en]

    In this paper, we report our ongoing work on safe and secure controller synthesis for cyber-physical systems (CPS). Our approach separates the synthesis process into three phases, in which we alternatively perform exhaustive and selective exploration of the system’s state space. In this way, we combine the strengths of exhaustive search and learning to mitigate the state-space-explosion problem in controller synthesis while preserving the guarantee of safety and security. We implement the synthesis algorithms in the Rebeca (Reactive Objects Language) platform, which provides modelling, verification, and state-space visualization. We evaluate the new approach in an experiment, demonstrating the reduced number of explored states, which shows the potential of our approach for synthesizing safe and secure controllers for complex CPS.

  • 20.
    Gualandi, Gabriele
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Innovation and Product Realisation.
    Papadopoulos, Alessandro
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Worst-Case Impact Assessment of Multi-Alarm Stealth Attacks Against Control Systems with CUSUM-Based Anomaly Detection2023In: 2023 IEEE INTERNATIONAL CONFERENCE ON AUTONOMIC COMPUTING AND SELF-ORGANIZING SYSTEMS, ACSOS, 2023, no 4th IEEE International Conference on Autonomic Computing and Self-Organizing Systems (ACSOS), p. 117-126Conference paper (Other academic)
    Abstract [en]

    Manipulating sensor data can deceive cyber-physical systems (CPSs), leading to hazardous conditions in physical plants. An Anomaly Detection System (ADS) like CUSUM detects ongoing attacks by comparing sensor signals with those generated by a model. However, physics-based methods are threshold-based, which can result in both false positives and undetectable attacks. This can lead to undetected attacks impacting the system state and potentially causing large deviations from the desired behavior. In this paper, we introduce a metric called transparency that uniquely quantifies the effectiveness of an ADS in terms of its ability to prevent state deviation. While existing research focuses on designing optimal zero-alarm stealth attacks, we address the challenge of detecting more sophisticated multi-alarm attacks that generate alarms at a rate comparable to the system noise. Through our analysis, we identify the conditions that require the inclusion of multi-alarm scenarios in worst-case impact assessments. We also propose an optimization problem designed to identify multi-alarm attacks by relaxing the constraints of a zero-alarm attack problem. Our findings reveal that multi-alarm attacks can cause a more significant state deviation than zero-alarm attacks, emphasizing their critical importance in the security analysis of control systems.

  • 21.
    Guo, Yangyi
    et al.
    Department of Biomedical Engineering, College of Precision Instruments and Optoelectronics Engineering, Tianjin University, China.
    He, Xiaohe
    Department of Biomedical Engineering, College of Precision Instruments and Optoelectronics Engineering, Tianjin University, China.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Liu, Bin
    Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, China.
    Liu, Shengchun
    Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, China.
    Qi, Hongzhi
    Department of Biomedical Engineering, College of Precision Instruments and Optoelectronics Engineering, Tianjin University, China; Academy of Medical Engineering and Translational Medicine, Tianjin University, China.
    The use of the general thermal sensation discriminant model based on CNN for room temperature regulation by online brain-computer interface2023In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 241, article id 110494Article in journal (Refereed)
    Abstract [en]

    Brain-computer interface (BCI) technology can realize dynamic room temperature adjustment based on individual real-time thermal sensation, which can provide the basis for future intelligent buildings. However, the generalization ability of previous thermal sensation discrimination model (TSDM) is limited, which is a serious obstacle to the application. In this paper, a general TSDM was developed by using convolutional neural network (CNN), which can be well applied to new subjects. In the study, the CNN-TSDM was established and evaluated based on the offline experimental data, and then the BCI closed-loop online room temperature control experiment was carried out based on this CNN-TSDM to further verify. The offline analysis results show that the recognition performance of CNN-TSDM in new subjects is significantly higher than that of typical shallow learning algorithms, and its area under the ROC curve (AUC) value reaches 0.789. In the online experiments of the two simulated environments, BCI using the CNN-TSDM dynamically controlled the air conditioning to improve the room temperature to the comfortable level according to the subjects' thermal sensation. The subjective score of subjects decreased from 3.1 to 3.0 for the hot uncomfortable to 1.1 and 1.2 for the cool comfortable (p < 0.001, p < 0.001). Moreover, in a hotter simulated experimental environment, BCI automatically controlled the air conditioner for longer cooling to obtain a same degree of thermal comfort. The total cooling time (p < 0.05) and the single cooling time (p < 0.05) of the air conditioner were significantly increased. This further confirmed the effectiveness and robustness of the general CNN-TSDM.

  • 22.
    Gärtner, Johan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Johansson, Philip
    Mälardalen University, School of Innovation, Design and Engineering.
    AN ADAPTIVE CONTROL SYSTEM BASED ON PID, I2PD AND RLS, A SIMULATED DESIGN FOR UAVS2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    During this master thesis an adaptive control system for angular velocity was developed. The approach focuses on radio controlled quadrotors and thereby targets a computational efficient solution. The adaptation is divided into two steps. First, an Integral Squared Plus Time Delay (I2PD) model estimation is done through the Recursive Least Squares (RLS) algorithm. Second, control parameters for the quadrotors Proportional Integral Derivative (PID) controller are found by using empirically modified Tuning Rules (TRs) which are based on the I2PD model. Simulation results show the benefits of an adaptive tuning algorithm in regards of the time consuming process of manually tuning a PID controller as well as robustness against both predictable and unpredictable system changes. This includes actuator degradation, battery consumption, changes in weight or inertia etc. However, it is apparent that the tuning algorithm demands an arbitrary initial approximation to be stable at initialization.

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  • 23.
    Hasan, Shahriar
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Fail-Operational and Fail-Safe Vehicle Platooningin the Presence of Transient Communication Errors2022Report (Other academic)
    Abstract [en]

    Recent advances in wireless technology facilitating Vehicle-to-Vehicle (V2V)communication has paved the way towards a more connected and Cooperative-Intelligent Transportation System (C-ITS). It has unveiled the possibility of many services which are anticipated to make the road transport eco system safer, cleaner, and more sustainable. Platooning is one such application that is expected to soon appear on the roads. In platooning, a group of connected and highly automated vehicles follow a lead vehicle with short inter-vehicle distances. They adapt their speed, acceleration, steering angle, etc., with the help of on-board sensors and inter-vehicle communications. Due to the highly automated driving and the very short inter-vehicle distances required to achieve fuel-efficiency, platooning is a complex and safety-critical system of systems. As a result, the consequences of component or system failure can endanger human life, cause damage to property, or the environment. Given that V2V communication is subject to packet losses due to interference, path loss, fading and shadowing, it is usually desirable to maintain a sufficient level of platooning functionality without compromising safety also during periods of transient errors. Moreover, a platoon can experience different sensor failures, permanent hardware/software failures, or a suddenly appearing road hazard,e.g., a moose. The platoon should, therefore, also be capable of dissolving and transitioning into a fail-safe state by performing emergency braking, safestop, or manual handover without causing any harm to the equipment, people, or to the environment. This research work focuses on incorporating fail-operational mechanisms in platooning in a fuel-efficient and safe way, even inthe presence of transient errors and enable transition into a fail-safe state inthe event of an emergency. To this end, a platoon runtime manager is proposed, which monitors the channel quality and keeps the platoon operational in cases of temporal failures by degrading the platoon performance to the level at which it will remain acceptably safe. Simulation results demonstrate that the runtime manager can avoid collisions in the platoon and still maintain fair performance in terms of fuel-efficiency by either adjusting the inter-vehicle distances or switching to a different controller during runtime. Furthermore, two emergency braking strategies, namely Synchronized Braking and Adaptive Emergency Braking, are proposed to address the emergency events that can arise while platooning. These braking strategies are compared to several state-of-the-art braking strategies in terms of their ability to avoid collisions, and the distance traversed by the lead vehicle. Simulation results show that Synchronized Braking and Adaptive Emergency Braking strategies can ensure fail-safe platooning while the other braking strategies fail to do so. Moreover, a simulation tool named PlatoonSAFE has been developed to facilitate the evaluation of fail-operational and fail-safe mechanisms in platooning under realistic traffic, vehicle dynamics, and communication scenarios. 

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  • 24.
    Hernández González, Francisco
    Mälardalen University, School of Innovation, Design and Engineering.
    Planar Robot Arm Modelling and Control2012Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The thesis objective is to model a one link robotic arm mounted on a sliding mobile platform and to investigate different control strategies under the effect of gravity and external force disturbance. For simplicity the robotic set up can be modelled and controlled as an inverted pendulum moving on a non constant sloping surface.

    Firstly the control is done on level ground. This lower mathematical complexity will be taken as an advantage to approach the analysis on aspects more related with control theory: several control techniques and observers, steady state error study, etcetera.

    Afterwards the control is generalized for sloping grounds. This chapter will seek situations closer to reality, the purpose is to design something with practical interests, like model a Segway.

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  • 25.
    Iplik, Esin
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Metals, Combustion and Energy, Linde Technology, 85716 Unterschleißheim, Germany.
    Aslanidou, Ioanna
    Mälardalen University, School of Innovation, Design and Engineering, Innovation and Product Realisation.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    A Feedforward Model Predictive Controller for Optimal Hydrocracker Operation2022In: Processes, E-ISSN 2227-9717, Vol. 10, no 12, p. 2583-2583Article in journal (Refereed)
    Abstract [en]

    Hydrocracking is an energy-intensive process, and its control system aims at stable product specifications. When the main product is diesel, the quality measure is usually 95% of the true boiling point. Constant diesel quality is hard to achieve when the feed characteristics vary and feedback control has a long response time. This work suggests a feedforward model predictive control structure for an industrial hydrocracker. A state-space model, an autoregressive exogenous model, a support vector machine regression model, and a deep neural network model are tested in this structure. The resulting reactor temperature decisions and final diesel product quality values are compared against each other and against the actual measurements. The results show the importance of the feed character measurements. Significant improvements are shown in terms of product quality as well as energy savings through decreasing the heat duty of the preheating furnace. 

  • 26.
    Johansson, Bjarne
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. Abb Process Automation, Process Control Platform, Västerås, Sweden.
    Holmgren, O.
    Abb Process Automation, Process Control Platform, Västerås, Sweden.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Papadopoulos, Alessandro
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Partible State Replication for Industrial Controller Redundancy2024In: Proceedings of the IEEE International Conference on Industrial Technology, Institute of Electrical and Electronics Engineers Inc. , 2024Conference paper (Refereed)
    Abstract [en]

    Distributed control systems are part of the often invisible backbone of modern society that provides utility services like water and electricity. Their uninterrupted operation is vital, and unplanned stops due to failure can be expensive. Critical devices, like controllers, are often duplicated to minimize the service stop probability, with a secondary controller acting as a backup to the primary. A seamless takeover requires that the backup has the primary's latest state, i.e., the primary has to replicate its state to the backup. While this method ensures high availability, it can be costly due to hardware doubling. This work proposes a state replication solution that doesn't require the backup to store the primary state, separating state storage from the backup function. Our replication approach allows for more flexible controller redundancy deployments since one controller can be a backup for multiple primaries without being saturated by state replication data. Our main contribution is the partible state replication approach, realized with a distributed architecture utilizing a consensus algorithm. A partial connectivity-tolerant consensus algorithm is also an additional contribution.

  • 27.
    Khan, A.
    et al.
    Metaverse Research Institute, School of Computer Science and Cyber Engineering, Guangzhou University, Guangzhou, China.
    Hassan, W. U.
    Department of Mathematics and Statistics, The University of Lahore, Sargodha, Pakistan.
    Manzor, Adnan
    Mälardalen University, School of Education, Culture and Communication, Educational Sciences and Mathematics.
    Ahmed, S.
    Department of Physics, The University of Lahore, Sargodha, Pakistan.
    Niazi, A. U. K.
    Department of Mathematics and Statistics, The University of Lahore, Sargodha, Pakistan.
    Strengthening stability with centralized event-triggered control system with the disturbances and artificial time delay in wireless connected vehicle platooning (CVSs)2024In: Systems Science & Control Engineering: An Open Access Journal, E-ISSN 2164-2583, Vol. 12, no 1, article id 2342818Article in journal (Refereed)
    Abstract [en]

    This paper addresses the difficulties with connected vehicle systems (CVSs), particularly with vehicle platooning, are examined in this paper. For leader and follower-connected vehicles, the control protocol (which includes artificial delays, disturbances and proportional gains) is implemented. With tracking error systems, system dynamics are modelled while taking outside influences into consideration. Using creative thinking, a centralized event-triggered control system is implemented to maximize fleet wide communication updates. System stability is guaranteed by this centralized method in combination with quadratic form Lyapunov stability analysis. The risk of zeno behaviour is reduced by an event-triggered communication condition that is activated when a threshold is exceeded. The effectiveness of the centralized event-triggered system in improving stability and resilience in connected vehicle platooning scenarios is evaluated numerically through simulations.

  • 28.
    Kujan, Dzana
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Radisavljevic, Nikola
    Mälardalen University, School of Innovation, Design and Engineering.
    Migrating process automation applications to mobile2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
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  • 29.
    Leander, Björn
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. ABB AB, Sweden.
    Dynamic Access Control for Industrial Systems2023Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Industrial automation and control systems (IACS) are taking care of our most important infrastructures, providing electricity and clean water, producing medicine and food, along with many other services and products we take for granted. The continuous, safe, and secure operation of such systems are obviously of great importance. Future iterations of IACS will look quite different from the ones we use today. Modular and flexible systems are emerging, powered by technical advances in areas such as artificial intelligence, cloud computing, and motivated by fluctuating market demands and faster innovation cycles. Design strategies for dynamic manufacturing are increasingly being adopted. These advances have a fundamental impact on industrial systems at component as well as architectural level. 

    As a consequence of the changing operational requirements, the methods used for protection of industrial systems must be revisited and strengthened. This for example includes access control, which is one of the fundamental cyber­security mechanisms that is hugely affected by current developments within IACS. The methods currently used are static and coarse-grained and therefore not well suited for dynamic and flexible industrial systems. A transition in security model is required, from implicit trust towards zero-trust, supporting dynamic and fine-grained access control. 

    This PhD thesis discusses access control for IACS in the age of Industry 4.0, focusing on dynamic and flexible manufacturing systems. The solutions pre­sented are applicable at machine-to-machine as well as human-to-machine in­teractions, using a zero-trust strategy. An investigation of the current state of practice for industrial access control is provided as a starting point for the work. Dynamic systems require equally dynamic access control policies, why several approaches on how dynamic access control can be achieved in indus­trial systems are developed and evaluated, covering strategies for policy for­mulations as well as mechanisms for authorization enforcement. 

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  • 30.
    Leander, Björn
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Causevic, Aida
    Lindström, Tomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Hansson, Hans
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Access Control Enforcement Architectures for Dynamic Manufacturing Systems2023In: Proc. - IEEE Int. Conf. Softw. Architecture, ICSA, Institute of Electrical and Electronics Engineers Inc. , 2023, p. 82-92Conference paper (Refereed)
    Abstract [en]

    Industrial control systems are undergoing a trans-formation driven by business requirements as well as technical advances, aiming towards increased connectivity, flexibility and high level of modularity, that implies a need to revise existing cybersecurity measures. Access control, being one of the major security mechanisms in any system, is largely affected by these advances.In this article we investigate access control enforcement architectures, aiming at the principle of least privilege1 in dynamically changing access control scenarios of dynamic manufacturing systems. Several approaches for permission delegation of dynamic access control policy decisions are described. We present an implementation using the most promising combination of architecture and delegation mechanism for which available industrial standards are applicable.

  • 31.
    Lindberg, Carl-Fredrik
    et al.
    ABB Corporate Research, Sweden.
    Isaksson, Alf
    ABB Corporate Research, Sweden.
    Comparison of different sampling schemes for wireless control subject to packet losses2015In: First International Conference on Event-Based Control, Communication, and Signal Processing, 2015Conference paper (Refereed)
    Abstract [en]

    Three different approaches to reduce the amount of communication in wireless control subject to packet losses have been evaluated in an extensive simulation study. The sampling approaches are: slow periodic, event-based and self-triggered sampling. They are ranked based on their integrated absolute error (IAE) control performance and also compared with fast periodic sampling. The three approaches have surprisingly equal control performance in the nominal case (without packet losses) for a wide range of test scenarios (process models, controller tunings etc.). With packet losses the importance of re-transmissions becomes evident.

  • 32.
    Lindberg, Carl-Fredrik
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zahedian, Kourosh
    ABB AB, Västerås, Sweden.
    Solgi, Maryam
    ABB AB, Västerås, Sweden.
    Lindkvist, Rickard
    ABB AB, Västerås, Sweden.
    Potential and limitations for industrial demand side management2014In: Energy Procedia, ISSN 1876-6102, Vol. 61, p. 415-418Article in journal (Refereed)
    Abstract [en]

    The growing share of variable renewable power such as wind and solar photovoltaic (PV) emphasize the importance of demand side management. In a couple of years consumers have to adapt their consumption more to available generated power in order to maintain grid stability and to reduce their electricity costs. In this study the potential and limitations for demand side management in about 15 different companies in Sweden has been investigated. A brief description of some of the company’s production process is given, with focus on electrical consumption. Suggestions on different demand side management possibilities are presented as well as limitations. The suggestions are given for different time horizons, from load shifting between hours, to weeks and years. Potential savings achieved with demand side management have also been evaluated based on historical electricity prices from different countries.

  • 33.
    Liu, S.
    et al.
    Tianjin Key Lab of Refrigeration Technology, Tianjin University of Commerce, Tianjin, China.
    Hu, C.
    Tianjin Key Lab of Refrigeration Technology, Tianjin University of Commerce, Tianjin, China.
    Dong, Beibei
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Improvement of control strategy of CO2 capture from biomass CHP plant by chemical absorption2022In: Clean Coal Technology, ISSN 1006-6772, Vol. 28, no 9, p. 112-121Article in journal (Refereed)
    Abstract [en]

    When capturing CO2 from biomass fired combined heat and power (CHP) plants, the changes in the feedstock and the heat and electricity demands affect the performance of chemical absorption CO2 capture system. To handle such impact, this paper proposed an improved reboiler duty control strategy (control strategy B) based on the evaluation of the control performance of the traditional feedback control strategy (control strategy A) to achieve a constant capture rate. Control strategy B is based on control strategy A, and introduces feedforward compensation based on rich solution flow rate to form a feedforward plus feedback control strategy. This work aimed to find a control strategy suitable for chemical absorption CO2 capture from biomass CHP, by comparing the control performance, capture system performance and flexible operation performance of both control strategies. Based on the dynamic simulations of CO2 capture from actual biomass fired CHP plant, it is found that compared with the control strategy A, the feedforward compensation of the control strategy B can reduce the response time of the reboiler duty to external disturbances, and improve the timeliness and accuracy of the regulation of reboiler duty. The settling time of capture rate is reduced by 54 mins with the control strategy B. Facing the flexible change of capture rate setpoint, the time required for the stabilization of capture rate is reduced by 57.9% with control strategy B. Under the continuous external disturbance, the capture rate is maintained at ±3% of the setpoint with control strategy B. At the same time, the energy penalty is reduced by 0.14%, and the total captured CO2 is increased by 0.35%. In addition, the results of dynamic simulation and traditional steady-state simulation show that the dynamic simulation can reflect the impact of external disturbances on the capture system more accurately, and provide a reference for the integration and optimization of related processes.

  • 34.
    Liu, Z
    et al.
    College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao, China.
    Liu, Z.
    College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao, China; Institute of Building Environment and Sustainability Technology, School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, China.
    Liu, G.
    Institute of Building Environment and Sustainability Technology, School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, China.
    Yang, Xiaohu
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Institute of Building Environment and Sustainability Technology, School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, China.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Melting assessment on the effect of nonuniform Y-shaped fin upon solid–liquid phase change in a thermal storage tank2022In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 321, article id 119330Article in journal (Refereed)
    Abstract [en]

    This study provides an alternative solution to the improvement on solid–liquid phase change by designing a Y-shaped fin in a nonuniform pattern along the gravity direction. A numerical model is established and validated through the present measurement and data in literature. Six cases with different Y-shaped fins and locations are designed and compared to the original straight fin case. Thermal assessments on the melting fraction, temperature field, velocity distribution, and uniformity for melting are made. Results demonstrate that the nonuniform melting features caused by the local natural convection are significantly eliminated by the novel nonuniform fin structure. The time required for melting the lower PCM is found to occupy more than 50% of the completely melting time. The accurate local heat transfer enhancement measures (bottom enhancement) are conducive to markedly reduce the full melting time by 21.5%, compared to the uniform fin pattern. Upon using finned thermal storage tank for a mobilized thermal storage truck (bare tube tank), the initial investment increases by 44.9% but the profit increases by 393.6% and the payback period reduces by 69.2%. The use of fin tube in heat storage tank can quickly obtain higher returns based on a small increase in initial investment. This work provides new insights into the understandings of the transient phase change process and the strategies for guiding the design for thermal energy storage tank. 

  • 35.
    Markovic, Filip
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Papadopoulos, Alessandro
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    On the convolution efficiency for probabilistic analysis of real-time systems2021In: Leibniz International Proceedings in Informatics, LIPIcs, Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing , 2021Conference paper (Refereed)
    Abstract [en]

    This paper addresses two major problems in probabilistic analysis of real-time systems: space and time complexity of convolution of discrete random variables. For years, these two problems have limited the applicability of many methods for the probabilistic analysis of real-time systems, that rely on convolution as the main operation. Convolution in probabilistic analysis leads to a substantial space explosion and therefore space reductions may be necessary to make the problem tractable. However, the reductions lead to pessimism in the obtained probabilistic distributions, affecting the accuracy of the timing analysis. In this paper, we propose an optimal algorithm for down-sampling, which minimises the probabilistic expectation (i.e., the pessimism) in polynomial time. The second problem relates to the time complexity of the convolution between discrete random variables. It has been shown that quadratic time complexity of a single linear convolution, together with the space explosion of probabilistic analysis, limits its applicability for systems with a large number of tasks, jobs, and other analysed entities. In this paper, we show that the problem can be solved with a complexity of O(nlog(n)), by proposing an algorithm that utilises circular convolution and vector space reductions. Evaluation results show several important improvements with respect to other state-of-the-art techniques. 

  • 36.
    Mehboob, Fozia
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Innovation and Product Realisation.
    Fattouh, Anas
    Mälardalen University, School of Innovation, Design and Engineering, Innovation and Product Realisation.
    Sahoo, Smruti
    Alstom, S-72136 Vasteras, Sweden..
    Synergizing Transfer Learning and Multi-Agent Systems for Thermal Parametrization in Induction Traction Motors2024In: Applied Sciences, E-ISSN 2076-3417, Vol. 14, no 11, article id 4455Article in journal (Refereed)
    Abstract [en]

    Maintaining optimal temperatures in the critical parts of an induction traction motor is crucial for railway propulsion systems. A reduced-order lumped-parameter thermal network (LPTN) model enables computably inexpensive, accurate temperature estimation; however, it requires empirically based parameter estimation exercises. The calibration process is typically performed in labs in a controlled experimental setting, which is associated with a lot of supervised human efforts. However, the exploration of machine learning (ML) techniques in varied domains has enabled the model parameterization in the drive system outside the laboratory settings. This paper presents an innovative use of a multi-agent reinforcement learning (MARL) approach for the parametrization of an LPTN model. First, a set of reinforcement learning agents are trained to estimate the optimized thermal parameters using the simulated data in several driving cycles (DCs). The selection of a reinforcement learning agent and the level of neurons in the RL model is made based on variability of the driving cycle data. Furthermore, transfer learning is performed on a new driving cycle data collected on the measurement setup. Statistical analysis and clustering techniques are proposed for the selection of an RL agent that has been pre-trained on the historical data. It is established that by synergizing within reinforcement learning techniques, it is possible to refine and adjust the RL learning models to effectively capture the complexities of thermal dynamics. The proposed MARL framework shows its capability to accurately reflect the motor's thermal behavior under various driving conditions. The transfer learning usage in the proposed approach could yield significant improvement in the accuracy of temperature prediction in the new driving cycles data. This approach is proposed with the aim of developing more adaptive and efficient thermal management strategies for railway propulsion systems.

  • 37.
    Merz, Mariann
    et al.
    SINTEF AS, Dept Math & Cybernet, N-7465 Trondheim, Norway..
    Pedro, Dario
    PDMFC, P-1300609 Lisbon, Portugal..
    Skliros, Vasileios
    Hellen Drones, Athens 10680, Greece..
    Bergenhem, Carl
    Qamcom, S-41285 Gothenburg, Sweden..
    Himanka, Mikko
    Centria Univ Appl Sci, Centria Res & Dev, Ylivieska 67100, Finland..
    Houge, Torbjorn
    Maritime Robot, N-7010 Trondheim, Norway..
    Matos-Carvalho, Joao P.
    Beyond Vis, P-3830352 Ilhavo, Portugal.;Univ Lusofona Humanidades & Tecnol, Cognit & People Centr Comp Labs COPELABS, Campo Grande 376, P-1749024 Lisbon, Portugal..
    Lundkvist, Henrik
    SINTEF AS, Dept Math & Cybernet, N-7465 Trondheim, Norway..
    Curuklu, Baran
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. Malardalen Univ, Sch Innovat Design & .
    Hamren, Rasmus
    Nordic Elect Partner, S-72215 Vasteras, Sweden..
    Ameri, Afshin E.
    Malardalen Univ, Sch Innovat Design & Engn, S-72220 Vasteras, Sweden..
    Ahlberg, Carl
    Malardalen Univ, Sch Innovat Design & Engn, S-72220 Vasteras, Sweden..
    Johansen, Gorm
    SINTEF AS, Dept Math & Cybernet, N-7465 Trondheim, Norway..
    Autonomous UAS-Based Agriculture Applications: General Overview and Relevant European Case Studies2022In: DRONES, ISSN 2504-446X, Vol. 6, no 5, article id 128Article in journal (Refereed)
    Abstract [en]

    Emerging precision agriculture techniques rely on the frequent collection of high-quality data which can be acquired efficiently by unmanned aerial systems (UAS). The main obstacle for wider adoption of this technology is related to UAS operational costs. The path forward requires a high degree of autonomy and integration of the UAS and other cyber physical systems on the farm into a common Farm Management System (FMS) to facilitate the use of big data and artificial intelligence (AI) techniques for decision support. Such a solution has been implemented in the EU project AFarCloud (Aggregated Farming in the Cloud). The regulation of UAS operations is another important factor that impacts the adoption rate of agricultural UAS. An analysis of the new European UAS regulations relevant for autonomous operation is included. Autonomous UAS operation through the AFarCloud FMS solution has been demonstrated at several test farms in multiple European countries. Novel applications have been developed, such as the retrieval of data from remote field sensors using UAS and in situ measurements using dedicated UAS payloads designed for physical contact with the environment. The main findings include that (1) autonomous UAS operation in the agricultural sector is feasible once the regulations allow this; (2) the UAS should be integrated with the FMS and include autonomous data processing and charging functionality to offer a practical solution; and (3) several applications beyond just asset monitoring are relevant for the UAS and will help to justify the cost of this equipment.

  • 38.
    Mostafa Orand, Seyed
    et al.
    Islamic Azad University, Science and Research Branch, Saveh, Iran .
    Mirzazadeh, Abolfazl
    Kharazmi University, Tehran, Iran.
    Ahmadzadeh, Farzaneh
    Islamic Azad University, Karaj Branch, Iran.
    Talebloo, Farid
    Sufi Razi, Zanjan, Iran.
    Optimisation of the Inflationary Inventory Control Model under Stochastic Conditions with Simpson Approximation: Particle Swarm Optimisation Approach2015In: Iranian Journal of Management Studies, ISSN 2008-7055, Vol. 8, no 2, p. 203-220Article in journal (Refereed)
  • 39.
    Nylander, Michelle
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Aparicio Tomas, Elena
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    ANALYSIS AND OPTIMIZATION OF ENERGY FLOWS IN A PULP MILL2008In: Proceedings of Control Systems,  2008 / [ed] Andrea Borrelli, Vancouver: TAPPI Press , 2008Conference paper (Refereed)
    Abstract [en]

    In this paper the digester house process variables

    are first studied to identify the process variations in

    different time perspectives. The focus is on the

    perspective of controlling the process on-line for

    the next 24 hours. With a mathematical model first

    the cook and the flows associated with the digester

    house are modelled. From this different scenarios

    with different “faults” are implemented in the

    model and compared to the process data. From this

    the performance can be predicted for different

    conditions. Key numbers are determined from this

    and these are used together with suitable objective

    functions to make optimal production planning for

    model based control. The set points are sent to the

    control system. By determining the reactivity of

    different qualities of wood chips by measuring NIR

    and measuring final kappa, a tool for feed forward

    control is developed.

  • 40.
    Packalén, Sture
    et al.
    Uppsala universitet.
    Daniels, Mats
    Uppsala universitet.
    Hansson, Hans
    Uppsala universitet.
    MÄTNING OCH STYRNING1985 (ed. 1)Book (Other (popular science, discussion, etc.))
  • 41.
    Papadopoulos, Alessandro
    et al.
    Lund University, Sweden.
    Maggio, Martina
    Lund University, Sweden.
    Terraneo, Federico
    Politecnico di Milano, Italy.
    Leva, Alberto
    Politecnico di Milano, Italy.
    A Dynamic Modelling Framework for Control-based Computing System Design2015In: Mathematical and Computer Modelling of Dynamical Systems, ISSN 1387-3954, E-ISSN 1744-5051, Vol. 21, no 3, p. 251-271Article in journal (Refereed)
    Abstract [en]

    This manuscript proposes a novel viewpoint on computing systems’ modelling. The classical approach is to consider fully functional systems and model them, aiming at closing some external loops to optimize their behaviour. On the contrary, we only model strictly physical phenomena, and realize the rest of the system as a set of controllers. Such an approach permits rigorous assessment of the obtained behaviour in mathematical terms, which is hardly possible with the heuristic design techniques, that were mainly adopted to date. The proposed approach is shown at work with three relevant case studies, so that a significant generality can be inferred from it.

  • 42.
    Papadopoulos, Alessandro
    et al.
    Politecnico di Milano, Italy.
    Prandini, Maria
    Politecnico di Milano, Italy.
    Model reduction of switched affine systems2016In: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 70, p. 57-65Article in journal (Refereed)
    Abstract [en]

    This paper addresses model reduction and extends balanced truncation to the class of switched affine systems with endogenous switching. The switched affine system is rewritten as a switched linear one with state resets that account for the affine terms. Balanced truncation can then be applied to each mode dynamics, independently. As a result, different reduced state vectors are associated with the different modes, and reset maps are here appropriately redefined so as to account and compensate for this mismatch, possibly preserving the continuity of the output. The overall behavior of the reduced switched system is determined by both the selected reduction per mode and the adopted reset maps. In this paper, we consider a stochastic setting and propose a randomized method for the selection of the reduced order. The performance of the proposed approach is illustrated through a multi-room temperature control example.

  • 43.
    Paulsson, Christian
    Mälardalen University, School of Innovation, Design and Engineering.
    Dasher the running robot2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
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    Dasher the running robot
  • 44.
    Persson, Niklas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Control and Navigation of an Autonomous Bicycle2023Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Autonomous control of mobile robots is a research topic that has received a lot of interest. There are several challenging problems associated with autonomous mobile robots, including low-level control, localisation, and navigation. Most research in the past has focused on developing algorithms for three or four-wheeled mobile robots, such as autonomous cars and differential drive robots, which are statically stable systems. In this thesis, autonomous two-wheeled robots are considered, such as autonomous bicycles, which are naturally unstable systems, and without proper actuation, they will lose balance and fall over. Thus, before developing algorithms for higher-level functionality such as localisation and navigation of an autonomous bicycle, the balance of the bicycle needs to be addressed. This is an interesting research problem as the bicycle is a statically unstable system that has proven difficult to control, but given adequate forward velocity, it is possible to balance a bicycle using only steering actuation. Moreover, given a sufficient forward velocity, the bicycle can even become self-stabilised.

    In this thesis, the balance and trajectory tracking of an autonomous bicycle is investigated. First, we propose an extension of previously proposed bicycle models to capture the steering dynamics including the motor used for controlling the handlebar. Next, several control methods which can stabilise an autonomous bicycle by actuation of the steering axis and the forward velocity of the bicycle are developed. The controllers are compared in simulations on both a linear and nonlinear bicycle model. The simulation evaluation proceeds with experiments conducted on an instrumented bicycle running on a bicycle roller. Moreover, trajectory tracking of an autonomous bicycle is addressed using a model predictive controller approach where the reference lean angle is computed at every sample interval and is tracked by the balance controller in the inner loop. Finally, path planning in a static environment is considered where the proposed strategy realises a smooth path that adheres to the kinematic and dynamic constraints of the bicycle while avoiding obstacles and optimises the number of heading changes and the path distance. The results obtained from detailed multibody simulations highlight the feasibility of the balance controller, trajectory tracking controller, and path planner. 

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  • 45.
    Rahman, Hamidur
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ahmed, Mobyen Uddin
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Begum, Shahina
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Non-Contact Physiological Parameters Extraction Using Facial Video Considering Illumination, Motion, Movement and Vibration2020In: IEEE Transactions on Biomedical Engineering, ISSN 0018-9294, E-ISSN 1558-2531, Vol. 67, no 1, p. 88-98, article id 8715455Article in journal (Refereed)
    Abstract [en]

    Objective: In this paper, four physiological parameters, i.e., heart rate (HR), inter-beat-interval (IBI), heart rate variability (HRV), and oxygen saturation (SpO2), are extracted from facial video recordings. Methods: Facial videos were recorded for 10 min each in 30 test subjects while driving a simulator. Four regions of interest (ROIs) are automatically selected in each facial image frame based on 66 facial landmarks. Red-green-blue color signals are extracted from the ROIs and four physiological parameters are extracted from the color signals. For the evaluation, physiological parameters are also recorded simultaneously using a traditional sensor 'cStress,' which is attached to hands and fingers of test subjects. Results: The Bland Altman plots show 95% agreement between the camera system and 'cStress' with the highest correlation coefficient R = 0.96 for both HR and SpO2. The quality index is estimated for IBI considering 100 ms R-peak error; the accumulated percentage achieved is 97.5%. HRV features in both time and frequency domains are compared and the highest correlation coefficient achieved is 0.93. One-way analysis of variance test shows that there are no statistically significant differences between the measurements by camera and reference sensors. Conclusion: These results present high degrees of accuracy of HR, IBI, HRV, and SpO2 extraction from facial image sequences. Significance: The proposed non-contact approach could broaden the dimensionality of physiological parameters extraction using cameras. This proposed method could be applied for driver monitoring application under realistic conditions, i.e., illumination, motion, movement, and vibration.

  • 46.
    Rahman, Moksadur
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Fentaye, Amare Desalegn
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zaccaria, Valentina
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Aslanidou, Ioanna
    Mälardalen University, School of Innovation, Design and Engineering, Innovation and Product Realisation.
    Dahlquist, Erik
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Kyprianidis, Konstantinos
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    A Framework for Learning System for Complex Industrial Processes2020In: AI and Learning Systems - Industrial Applications and Future Directions / [ed] Konstantinos Kyprianidis and Erik Dahlquist, IntechOpen , 2020, 1, p. 29-Chapter in book (Refereed)
    Abstract [en]

    Due to the intense price-based global competition, rising operating cost, rapidly changing economic conditions and stringent environmental regulations, modern process and energy industries are confronting unprecedented challenges to maintain profitability. Therefore, improving the product quality and process efficiency while reducing the production cost and plant downtime are matters of utmost importance. These objectives are somewhat counteracting, and to satisfy them, optimal operation and control of the plant components are essential. Use of optimization not only improves the control and monitoring of assets, but also offers better coordination among different assets. Thus, it can lead to extensive savings in the energy and resource consumption, and consequently offer reduction in operational costs, by offering better control, diagnostics and decision support. This is one of the main driving forces behind developing new methods, tools and frameworks. In this chapter, a generic learning system architecture is presented that can be retrofitted to existing automation platforms of different industrial plants. The architecture offers flexibility and modularity, so that relevant functionalities can be selected for a specific plant on an as-needed basis. Various functionalities such as soft-sensors, outputs prediction, model adaptation, control optimization, anomaly detection, diagnostics and decision supports are discussed in detail.

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    fulltext
  • 47.
    Rezaei, Amin
    et al.
    University of Louisiana at Lafayette, Lafayette, United States .
    Daneshtalab, Masoud
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Zhao, Dan
    Old Dominion University, Norfolk, United States .
    Modarressi, Mehdi
    University of Tehran, Tehran, Iran .
    SAMi: Self-aware migration approach for congestion reduction in NoC-based MCSoC2016In: International System on Chip Conference, IEEE Computer Society, 2016, p. 145-150Conference paper (Refereed)
    Abstract [en]

    Many-Core System-on-Chips (MCSoCs) require efficient task migration approach in order to reach system performance objectives such as load balancing, communication optimization, fault tolerance, and temperature control. In this paper an efficient self-aware migration approach is introduced for NoC-based MCSoCs using a centralized feedback controller in order to control the congestion over the system. The proposed approach is divided into four main steps: predicting behavior of the application, defining reliable triggers to initiate task migration, introducing cost comparison functions, and presenting a streamlined controlling mechanism to migrate tasks. The experimental results affirm that the proposed self-aware migration approach can help achieving significant throughput and system utilization while efficiently controlling system congestion.

  • 48.
    Rönnmark, Alfred
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Landré, Dennis
    Mälardalen University, School of Innovation, Design and Engineering.
    IMPLEMENTATION OF DIRECT DATA-DRIVEN CONTROL ON AN INSTRUMENTED BICYCLE2024Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Data-Driven Control (DDC) is an active field of research in modern control theory, providing exciting new methods for both model identification and controller design that leverage data to avoid time-consuming manual methods for identification and controller tuning. This thesis presents a practical application of direct Data-Driven Control where the task was to balance an instrumented bicycle at a constant velocity by controlling the steering angle. Exploring the potential of direct DDC as a stabilisation method for bicycles could improve efficiency and effectiveness in controlling similar unstable and nonlinear systems. This approach could eliminate the need for complex modelling and parameter fine-tuning which are present in alternative methods. The approach involved modifying the hardware and software of an existing instrumented bicycle, collecting data, computing direct DDC feedback gains with different state and exploratory control signal combinations, and evaluating the performance of their associated controllers through practical experiments. The study found that 14 out of 48 controllers managed to balance the instrumented bicycle, with the careful selection of states, exploratory control signals, and sufficient size of the data collection set indicating to be the important factors for successful implementation of direct DDC. The thesis provides valuable insights into the practical implementation of direct DDC on unstable and nonlinear systems and highlights potential areas for future research

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    fulltext
  • 49.
    Salido Monzú, David
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Roldán Sánchez, Oliver
    Mälardalen University, School of Innovation, Design and Engineering.
    Robot Positioning System: Underwater Ultrasonic Measurement2009Independent thesis Advanced level (degree of Master (One Year)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    This document provides a description about how the problem of the detection of thecenter of a defined geometry object was solved.This named object has been placed in an experimental environment surrounded bywater to be explored using microwaves under the water, to try to find a possibletumor. The receiver antenna is fixed in the tip of the tool of an ABB robot.Due to this working method, it was necessary to locate the center of this object tomake correctly the microwave scanning turning always around the actual center. Thiswork not only consist in give a hypothetic solution to the people who gave us theresponsibility of solve their problem, it is also to actually develop a system whichcarries out the function explained before.For the task of measuring the distance between the tip of the tool where themicrowave antenna is, ultrasonic sensors has been used, as a complement of acomplete system of communication between the sensor and finally the robot handler,using Matlab as the main controller of the whole system.One of these sensors will work out of water, measuring the zone of the object which isout of the water. In the other hand, as the researching side of the thesis, a completeultrasonic sensor will be developed to work under water, and the results obtained willbe shown as the conclusion of our investigation.The document provides a description about how the hardware and software necessaryto implement the system mentioned and some equipment more which were essentialto the final implementation was developed step by step.

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    FULLTEXT01
  • 50.
    Salman Shaik, Mohammad
    et al.
    ABB AB, Västerås, Sweden.
    Mubeen, Saad
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Markovic, Filip
    Mälardalen University, School of Innovation, Design and Engineering, Innovation and Product Realisation.
    Papadopoulos, Alessandro
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Scheduling Elastic Applications in Compositional Real-Time Systems2021In: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA, Institute of Electrical and Electronics Engineers Inc. , 2021Conference paper (Refereed)
    Abstract [en]

    Many real-time applications have functional behaviour that requires variability in timing properties at runtime. The elastic task model provides a convenient mechanism to specify and encapsulate such variability and enables the modification of an application's periods during run-time to keep the application schedulable. Additionally, reservation-based scheduling techniques were proposed for the same purpose of taming unpredictability of timing variations, but with a different solution, i.e., by providing the spatial and temporal isolation for executing independent applications on the same hardware. In this paper, we combine the two approaches by proposing a two-level adaptive scheduling framework which is based on the elastic task model and the compositional framework based on the periodic resource model. The proposed framework minimises the number of requests for bandwidth adaption at the reservation (system) level and primarily enables schedulability by accounting for the application's elasticity by adjusting the periods. The motivation for this design choice is to rather localise the effect of the modifications within the application, without necessarily affecting all the applications at the system level compared to the changes made at the application level. The evaluation results show that the local application changes may often be enough to solve the problem of variability, significantly reducing the number of bandwidth adjustments, and therefore reducing the potential negative impact on all the applications of a system.

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