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  • 38601.
    Olguín Muñoz, Manuel
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Teknisk informationsvetenskap.
    Wang, Junjue
    Carnegie Mellon University.
    Satyanarayanan, Mahadev
    Carnegie Mellon University.
    Gross, James
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Teknisk informationsvetenskap.
    Demo: Scaling on the Edge – A Benchmarking Suite for Human-in-the-Loop Applications2018Inngår i: 2018 IEEE/ACM Symposium on Edge Computing (SEC), IEEE, 2018, s. 323-325, artikkel-id 08567677Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Benchmarking human-in-the-loop appli-cations running on edge computing in-frastructure is complex given their nature,which heavily depends on the actions takenby the human user. This limits reproducibil-ity as well as feasibility of performance eval-uations. We propose a methodology andpresent a benchmarking suite that can ad-dress these challenges. Our core idea restson recording traces of these applicationswhich are played out in a controlled fashionbased on an underlying model of human be-havior. The traces are exposed to the origi-nal backend compute process of the respec-tive human-in-the-loop application, gener-ating realistic feedback. This allows for anautomated system which greatly simplifiesbenchmarking large scale scenarios.

    Fulltekst (pdf)
    fulltext
  • 38602.
    Olin, Martin
    Luleå tekniska universitet, Institutionen för system- och rymdteknik.
    Evaluation of hash functions2019Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
  • 38603.
    Oliv, Rasmus
    Linköpings universitet, Institutionen för systemteknik, Elektroniska Kretsar och System.
    GPS-Tracking Device with Long Range and Bluetooth Low Energy Communication2019Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    The thesis is about the construction of a GPS-tracker that can read NFC (Near Field Communication)-tags and communicate with LoRa (Long Range) and BLE (Bluetooth low energy) and investigate which of the components in the GPS-tracker that consumes most power. The usage area for the GPS-tracker is to make the work on disaster affected sites more efficient and secure by having an operation leader that can organizing the operation with help of the information provided by the GPS-trackers that are placed on the injured people and recuing personnel. The GPS-tracker is built around the sensor development kit Thingy:52 from Nordic Semiconductor. The Firmware (FW) for the Thingy:52 is developed by modifying the provided factory FW by Nordic Semiconductor. The GPS-module and the NFC-reader showed to be the most power consuming parts of the GPS-tracker. An energy optimization proposal for these parts are given in the report. A proposal to a circuit diagram for the GPS-tracker is also given in the report, that can be used for future miniaturization of the GPS-tracker.

    Fulltekst (pdf)
    fulltext
  • 38604.
    Oliva, Gabriele
    et al.
    Univ Campus Biomed Roma, Dept Engn, Unit Automat Control, I-00128 Rome, Italy..
    Rikos, Apostolos
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Reglerteknik.
    Gasparri, Andrea
    Univ Roma Tre, Dept Engn, I-00146 Rome, Italy..
    Hadjicostis, Christoforos N.
    Univ Cyprus, Dept Elect & Comp Engn, CY-1678 Nicosia, Cyprus..
    Distributed Negotiation for Reaching Agreement Among Reluctant Players in Cooperative Multiagent Systems2022Inngår i: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 67, nr 9, s. 4838-4845Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this article, we propose a distributed negotiation framework that allows a set of cooperative agents to find a common ground with their neighbors while attempting to modify their initial opinion by the least possible amount. Based on such a framework, we develop a distributed agreement approach where the effort spent in the local agreement reflects the relevance of the agents in a weighted consensus process. In particular, we assume that players whose ideas happen to satisfactory mediate the standpoint of their interlocutors will end-up being more influential in the overall decision-making process. We conclude the article by applying the proposed methodology in the context of distributed data aggregation scenarios, as a way to mitigate the effect of outliers (e.g., faulty sensors).

  • 38605. Olivares-Galvan, J. C.
    et al.
    Campero-Littlewood, E.
    Hernandez-Avila, J. L.
    Escarela-Perez, R.
    Adame, S. M.
    Theocharis, Andreas
    Technol. & Educ. Inst. of Patras, Patras, Greece.
    Evaluation of stray losses in throats of distribution transformers using finite element simulation2012Inngår i: 2012 VI Andean Region International Conference, IEEE, 2012, s. 7-10Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper provides a numerical methodology to quantify the losses produced by induced currents in the metallic ducts (throats) used to enclose the bus bars connecting distribution transformers to switchgears. This calculation is important because some transformer manufacturers in Mexico don’t include throats in the load losses measurement. In particular, it presents the results of simulations made with commercial Finite-Element Software, to quantify the stray losses, originated by the induced currents, in throats of a 2000 kVA distribution transformer. The information provided by transformer’s manufacturers has been used judiciously in the creation of the numerical model. © 2012 IEEE.

  • 38606. Olivares-Galván, J. C.
    et al.
    Georgilakis, P. S.
    Theocharis, Andreas
    1: Dept. de Energia, Univ. Autonoma Metropolitana-Azcapotzalco, Mexico City, Mexico .
    Madrigal, M.
    Experimental investigation of parameters influencing transformer excitation current2010Inngår i: 7th Mediterranean Conference and Exhibition on Power Generation, Transmission, Distribution and Energy Conversion (MedPower 2010), 2010, nr 572 CPKonferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper quantifies experimentally the impact of ten parameters on transformer excitation current. These parameters belong to the following six categories: (1) annealing process, (2) mechanical process, (3) operating conditions, (4) magnetic material, (5) assembly process, and (6) core design process parameters. The conclusions of this research are very useful during both the design and production phases of transformers. Consequently, transformers can be designed and manufactured to fulfill the excitation current specifications.

  • 38607.
    Olivari, Maxime
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Simulator Design for the MMX rover2020Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Space projects involve particular strategies in system design such as simulation engineering.The french space agency uses this field of engineering in the developmentof a small vehicle (called rover) aiming to investigate one of the moons of Mars. Thecreation of this simulation environment starts with the design of its architecture.This study aims to derive this architecture. Based on the project documentation andobjectives it asks: What is the simulator architecture that enables the validation ofthe flight software embedded in the rover ?The collecting of validation needs from the core team consist a first step thatdefines the content of the architecture. The training on the simulator developmentplatform used at the french space agency provides the framing of this architecture.Taking into account this two steps lead to a relevant architecture that satisfy theproject needs.

    Fulltekst (pdf)
    fulltext
  • 38608.
    Oliveira, Bruno
    et al.
    Universidade Federal de Pernambuco, Centro de Informática, Brazil.
    Carvalho, Gustavo
    Universidade Federal de Pernambuco, Centro de Informática, Brazil.
    Mousavi, Mohammad Reza
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Sampaio, Augusto
    Universidade Federal de Pernambuco, Centro de Informática, Brazil.
    Simulation of hybrid systems from natural-language requirements2018Inngår i: 2017 13th IEEE Conference on Automation Science and Engineering (CASE), Piscataway, NJ: IEEE Computer Society, 2018, s. 1320-1325Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Cyber-physical systems are characterised by a massive and tight interaction between computer systems and physical components. Hybrid systems provide an abstraction for modelling cyber-physical systems by featuring the integration of discrete and continuous behavioural aspects. Simulation is an important tool for validating hybrid system models, which are often too complex to be treated using other validation and verification techniques. Motivated by the industrial need for such tools, we propose a strategy (h-NAT2TEST) for simulation of hybrid systems from natural-language requirements. Using the proposed approach, one writes the system specification using a controlled natural language, from which an informal semantics is automatically inferred based on the case grammar theory. Then, a formal representation is built considering a model of hybrid data-flow reactive systems (h-DFRS). Finally, in order to allow for rigorous simulation, an Acumen specification is derived from the h-DFRS model. Simulation is supported by the Acumen modelling environment. A DC-DC boost converter is used as a case study to illustrate the overall approach. © 2017 IEEE.

  • 38609.
    Oliveira, L.
    et al.
    Instituto de Telecomunicações Universidade Do Porto, Porto, Portugal.
    Almeida, Luis
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Lima, P.
    ISR/IST, Universidade de Lisboa, Lisboa, Portugal.
    Multi-hop routing within TDMA slots for teams of cooperating robots2015Inngår i: IEEE International Workshop on Factory Communication Systems - Proceedings, WFCS, 2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Small teams of cooperating robots have been shown to benefit from the increased reliability of synchronised message exchanges provided by TDMA-based schemes. However, such schemes may also impose a long propagation delay to communications between non neighbour robots. Such negative impact is further increased by long TDMA rounds, which favour reduced medium utilisation and energy consumption, and by decentralised mesh topologies, which increase the team coverage and layout flexibility. For small size teams, say up to 10 units, it is feasible to set-up a global TDMA framework as well as tracking the instantaneous network topology, making it available to each robot. In this work we use this knowledge to forward packets along their path within each TDMA slot. To that end, we present a novel communication protocol that combines global TDMA and multi-hop routing. It maintains the reliability benefits of the TDMA schemes while strongly reducing the end-to-end propagation delay of interactions between non neighbour robots. We validate our protocol with simulation results using OMNET++. In a worst-case topology scenario we achieved an end-to-end delay that can be as low as 35% that of a traditional TDMA implementation that forwards the packets to the immediate one-hop neighbours, only. In a concrete audio streaming application scenario reported in the literature for an alternative real-time token-passing protocol, our proposal achieves similar delays with significantly less management bandwidth.

  • 38610.
    Oliveira, L.
    et al.
    Universidade Do Porto, Porto, Portugal.
    Graca, R.
    Universidade Do Porto, Porto, Portugal.
    Martins, J.
    Universidade Do Porto, Porto, Portugal.
    Almeida, Luis
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Universidade Do Porto, Porto, Portugal.
    Managing high loads in WiFi with automatic synchronization and bandwidth control2015Inngår i: Proceeding - 2015 IEEE International Conference on Industrial Informatics, INDIN 2015, 2015, s. 937-942Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Mobile devices in industrial settings became commonplace with different handheld equipment and mobile robots using COTS WiFi interfaces for communication. This growth in the use of the wireless medium increases the potential for overload and consequent long delays and high losses. Traffic segregation with different Quality of Service (QoS) classes can attenuate the problem but does not solve it within each class. In this paper we propose an extension to the Reconfigurable and Adaptive TDMA protocol to cope with generic traffic and improve the performance of highly loaded WiFi networks. We benefit from the self-synchronization feature of the protocol to create disjoint slots without clock synchronization which are then made available to the protocol stack through a TUN/TAP virtual interface. Then we propose a cooperative bandwidth management to adjust the traffic generated by each node through the virtual interface to match the available bandwidth, granting high bandwidth utilization while avoiding overload. We validate our approach with several practical experiments that confirm the capacity to measure and track the actual bandwidth available for communication through the protocol, removing the bandwidth consumed by interference.

  • 38611.
    Oliveira, Luis
    et al.
    Högskolan Dalarna, Institutionen för kultur och samhälle, Företagsekonomi. Högskolan Dalarna, Institutionen för information och teknik, Mikrodataanalys. University of São Paulo, São Paulo, Brazil.
    Fleury, A.
    Fleury, M. T.
    Digital power: Value chain upgrading in an age of digitization2021Inngår i: International Business Review, ISSN 0969-5931, E-ISSN 1873-6149, Vol. 30, nr 6, artikkel-id 101850Artikkel i tidsskrift (Fagfellevurdert)
  • 38612.
    Oliveira Lunå, Torbjörn
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Medicinteknik och hälsosystem, Hälsoinformatik och logistik.
    Implementation av en vibrotaktil alarmklocka: Undersökning av lämpliga input-signaler och parametrar för ett behagligt och alert uppvaknande och tillhörande utvecklingskostnader2018Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Att köra fastän trötthet upplevs är en erkänd trafikfara. Om en förare idag kör när denne är trött klassas det som vårdslöshet i trafiken. Dock är det nästan omöjligt att vid en olycka påvisa att olyckan skedde för att en förare var trött. Det praktiska resultatet är att det lämnas åt föraren att själv avgöra om denne är för trött för att föra fram fordonet säkert. Hela situationen om att vara en trafikfara eller ej lämnas då åt en subjektiv bedömning.

     

    I denna rapport undersöks olika sömnstadier, och metoder för att avgöra när och hur det är lämpligast att vakna för att vakna i ett mer alert tillstånd. För att sedan använda de metoder som visar sig vara lämpade som indata och parametrar till en algoritm som ska avgöra när det är som lämpligast att vakna för att vakna mer alert. Rapporten gör också en kalkyl som kan användas för att fastställa prototypens utvecklingskostnader.

     

    Arbetet resulterar i en prototyp som föreslår en lösning till problemet med trötthet i trafiken. De kostnader som framkommer i samband med prototyputveckling fastställs och presenteras.

     

    Undersökningen och utvecklandet av den tekniska lösningen har delats upp i två moduler och kommer att göras i samverkan med en extern studentgrupp på skolan för elektroteknik och datavetenskap (EECS) vid Kungliga Tekniska högskolan.

    Fulltekst (pdf)
    Implementation av en vibrotaktil alarmklocka
  • 38613.
    Oliveira, Roger Alves de
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Bollen, Math H.J.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Deep learning for power quality2023Inngår i: Electric power systems research, ISSN 0378-7796, E-ISSN 1873-2046, Vol. 214, artikkel-id 108887Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    This paper aims to introduce deep learning to the power quality community by reviewing the latest applications and discussing the open challenges of this technology. Publications covering deep learning to power quality are stratified in terms of application, type of data, and learning technique. This work shows that the majority of the deep learning applications to power quality are based on unrealistic synthetic data and supervised learning without proper labelling. Some applications with deep learning have already been solved by previous machine learning methods or expert systems. The main barriers to implementing deep learning to power quality are related to lack of novelty, low transparency of the deep learning methods, and lack of benchmark databases. This work also discusses that even with automatic feature extraction by deep learning methods, power quality expert knowledge is still needed to implement and analyse the results. The main research gaps identified in this work are related to the applications of semi-supervised learning, explainable deep learning and hybrid approaches combining deep learning with expert systems. Suggestions for overcoming the present limitations are: providing a stronger collaboration among the grid stakeholders and academy to keep track of power quality events; proper labelling and enlarging of datasets in deep learning methods; explaining the end-to-end decision making of deep learning methods; providing open-access databases for comparison purposes.

  • 38614.
    Oliveira, Rui
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Reglerteknik.
    Motion Planning for Heavy-Duty Vehicles2019Licentiatavhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Autonomous driving is a disrupting technology that is expected to reshape transportation systems. The benefits of autonomous vehicles include, but are not limited to, safer transportation, increased economic growth, and broader access to mobility services. Industry and academia are currently researching a variety of topics related to autonomous driving, however, the focus seems to be on passenger vehicles. As a consequence, heavy-duty vehicles, which are a significant share of transportation systems, are overlooked, and the challenges associated with these vehicles are neglected.

    This thesis studies motion planning algorithms for heavy-duty vehicles. Motion planning is a fundamental part of autonomous vehicles, it is tasked with finding the correct sequence of actions that take the vehicle towards its goal. This work focuses on particular aspects that distinguish heavy-duty vehicles from passenger vehicles, and that call for novel developments within motion planning algorithms.

    We start by addressing the problem of finding shortest paths for a vehicle in obstacle-free environments. This problem has been studied since the fifties, but the addressed vehicle models are often simplistic. We propose a novel algorithm that is able to plan paths respecting complex vehicle actuator constraints associated with the slow dynamics of heavy vehicles.

    Using the previous method, we tackle the motion planning problem in environments populated with obstacles. Lattice-based motion planners, a popular choice for this type of scenario, come with drawbacks related to the sub-optimality of solution paths, and the discretization of the goal state. We propose a novel path optimization method, which is able to significantly reduce both problems. The resulting optimized paths contain less oscillatory behavior and arrive precisely at arbitrary non-discretized goal states.

    We then study the problem of bus driving in urban environments. It is shown how this type of driving is fundamentally different than that of other vehicles, due to the chassis configuration with large overhangs. To successfully maneuver buses, distinct driving objectives need to be used in planning algorithms. Moreover, a novel environment classification scheme must be introduced. The result is a motion planning algorithm that is able to mimic professional bus driver behavior, resulting in safer driving and increased vehicle maneuverability.

     

    Fulltekst (pdf)
    RuiOliveira-LicentiateThesis
  • 38615.
    Oliveira, Rui
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Planning and Motion Control in Autonomous Heavy-Duty Vehicles2014Student paper other, 20 poäng / 30 hpOppgave
    Abstract [en]

    Autonomous driving has been an important topic of research in recent years.

    In this thesis we study its application to Heavy Duty Vehicles, more specically,

    vehicles consisting of a truck and a trailer. An overview study is done on

    three fundamental steps of an autonomous driving system, planning, trajectory

    tracking and obstacle avoidance.

    In the planning part, we use RRT, and two other variants of the algorithm

    to nd trajectories in an unstructured environment,

    e.g., a mining site. A

    novel path optimization post-processing technique well suited for use with RRT

    solutions was also developed.

    For the trajectory tracking task several well-known controllers were tested,

    and their performance compared. An extension is proposed to one of the controllers

    in order to take into account the trailer. The performance evaluation

    was done on scaled truck systems in the Smart Mobility Lab at KTH.

    The obstacle avoidance is done with the aid of a simple, yet functional Model

    Predictive Controller. For this purpose, we developed dierent formulations

    of the optimization problem, corresponding to distinct optimization goals and

    vehicle models, in order to assess both the quality of the MPC, and of the

    assumed truck model.

    The outcome of this thesis is a fully autonomous system, able to plan and

    move in constrained environments, while avoiding unpredicted obstacles. It

    was implemented using a 1:32 scale remote controlled truck, commanded by a

    desktop computer.

    Fulltekst (pdf)
    fulltext
  • 38616.
    Oliveira, Rui Filipe De Sousa
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Reglerteknik.
    Motion Planning and Decision Making with applications to Truck-Trailers and Buses2022Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    This thesis focuses on motion planning algorithms for self-driving heavy-duty vehicles. Motion planning is a fundamental part of autonomous vehicles, tasked with finding the correct sequence of actions that take the vehicle towards its goal. This work focuses on the aspects that distinguish heavy-duty vehicles from passenger vehicles and require novel developments within motion planning algorithms. The proposed algorithms are studied in simulation environments and on two Scania prototype autonomous vehicles: a mining truck and a public transport bus.

    We start by addressing the problem of finding the shortest paths for a vehicle in obstacle-free environments. This problem has long been studied, but the considered vehicle models have been simplistic. We propose a novel algorithm that plans paths respecting complex vehicle actuator constraints associated with the slow dynamics of heavy vehicles.

    Using the previous method, we tackle the motion planning problem in environments with obstacles. Lattice-based motion planners, a popular choice for this type of scenario, come with drawbacks related to the sub-optimality of solution paths and the discretization of the goal state. We propose a novel path optimization method that significantly reduces both drawbacks. The resulting optimized paths contain less oscillatory behavior and arrive precisely at arbitrary non-discretized goal states.

    We then study the problem of bus driving in urban environments. In order to successfully maneuver buses, distinct driving objectives must be used in planning algorithms. Moreover, a novel environment classification and collision avoidance scheme must be introduced. The result is a motion planning algorithm that mimics professional bus driver behavior, resulting in safer driving and increased vehicle maneuverability.

    One particular challenge of driving in urban environments is common to buses and trucks with trailers, namely, that of centering the whole vehicle body on the road. In the case of buses, the long wheelbase introduces a conflict between centering the rear axle vehicle or centering the front axle. In the case of trucks with trailers, a similar conflict appears, this time between centering the truck body or centering the trailer body. We propose a framework to design motion planners that optimally trade-off between these conflicting objectives, resulting in planned paths that center the whole vehicle body, improving driving behavior.

    Finally, we study the challenges of interacting with human-driven vehicles. We propose a motion planning framework that addresses the multi-modality of human behaviors, the interactive nature of traffic, and the impact of the autonomous vehicle on human drivers' decision making. The result is a motion planner that can reason about multiple future outcomes of a traffic scene, minimizing the expected cost across all outcomes. Furthermore, we show that incorporating neuroscience-based decision making models of human drivers into the motion planner results in the autonomous vehicle taking safe but assertive maneuvers, reducing the conservativeness usually seen in autonomous vehicles.

    Fulltekst (pdf)
    fulltext
  • 38617.
    Oliveira, Rui Filipe De Sousa
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Reglerteknik. Scania, Autonomous Transport Solutions, Södertälje, Sweden.
    Cirillo, Marcello
    Scania.
    Mårtensson, Jonas
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Reglerteknik.
    Wahlberg, Bo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Reglerteknik.
    Combining Lattice-Based Planning and Path Optimization in Autonomous Heavy Duty Vehicle Applications2018Inngår i: 2018 IEEE Intelligent Vehicles Symposium (IV), Institute of Electrical and Electronics Engineers (IEEE), 2018, s. 2090-2097, artikkel-id 8500616Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Lattice-based motion planners are an established method to generate feasible motions for car-like vehicles. However, the solution paths can only reach a discretized approximation of the intended goal pose. Moreover, they can be optimal only with respect to the actions available to the planner, which can result in paths with excessive steering. These drawbacks have a negative impact when used in real systems. In this paper we address both drawbacks by integrating a steering method into a state-of-the-art lattice-based motion planner. Un- like previous approaches, in which path optimization happens in an a posteriori step after the planner has found a solution, we propose an interleaved execution of path planning and path optimization. The proposed approach can run in real-time and is implemented in a full-size autonomous truck, and we show experimentally that it is able to greatly improve the quality of the solutions provided by a lattice planner.

  • 38618.
    Oliveira, Rui Filipe De Sousa
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Reglerteknik.
    Lima, Pedro F.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Reglerteknik.
    Cirillo, M.
    Mårtensson, Jonas
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Reglerteknik.
    Wahlberg, Bo
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Trajectory Generation using Sharpness Continuous Dubins-like Paths with Applications in Control of Heavy-Duty Vehicles2018Inngår i: 2018 European Control Conference, ECC 2018, Institute of Electrical and Electronics Engineers Inc. , 2018, s. 935-940Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present a trajectory generation framework for control of wheeled vehicles under steering actuator constraints. The motivation is smooth driving of autonomous heavy-duty vehicles, which are characterized by slow actuator dynamics. In order to deal with the slow dynamics, we take into account rate and, additionally, torque limitations of the steering actuator directly. Previous methods only take into account limitations in the path curvature, which deals indirectly with steering rate limitations. We propose the new concept of Sharpness Continuous curves, which uses cubic curvature paths together with circular arcs to steer the vehicle. The obtained paths are characterized by a smooth and continuously differentiable steering angle profile. The final trajectories computed with our method provide low-level controllers with reference signals which are easier to track, resulting in improved performance. The smoothness of the obtained steering profiles also results in increased passenger comfort. The method is characterized by fast computation times. We detail possible path planning applications of the method, and conduct simulations that show its advantages and real-time capabilities.

  • 38619.
    Oliveira, Rui Filipe De Sousa
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Reglerteknik.
    Lima, Pedro F.
    Scania, Autonomous Transport Solutions, Södertälje, Sweden.
    Pereira, Goncalo Collares
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Reglerteknik.
    Mårtensson, Jonas
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Reglerteknik.
    Wahlberg, Bo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Reglerteknik.
    Path planning for autonomous bus driving in highly constrained environments2019Inngår i: Proceedings 2019 IEEE Intelligent Transportation Systems Conference (ITSC), Institute of Electrical and Electronics Engineers (IEEE) , 2019, s. 2743-2749Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Driving in urban environments often presents difficult situations that require expert maneuvering of a vehicle. These situations become even more challenging when considering large vehicles, such as buses. We present a path planning framework that addresses the demanding driving task of buses in highly constrained environments, such as urban areas. The approach is formulated as an optimization problem using the road-aligned vehicle model. The road-aligned frame introduces a distortion on the vehicle body and obstacles, motivating the development of novel approximations that capture this distortion. These approximations allow for the formulation of safe and accurate collision avoidance constraints. Unlike other path planning approaches, our method exploits curbs and other sweepable regions, which a bus must often sweep over in order to manage certain maneuvers. Furthermore, it takes full advantage of the particular characteristics of buses, namely the overhangs, an elevated part of the vehicle chassis, that can sweep over curbs. Simulations are presented, showing the applicability and benefits of the proposed method.

  • 38620.
    Oliveira, Rui Filipe De Sousa
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Reglerteknik. Autonomous Transport Solutions, Scania Cv Ab, Södertälje, Sweden.
    Ljungqvist, Oskar
    Division of Automatic Control, Department of Electrical Engineering, Linköping University.
    Lima, Pedro F.
    Autonomous Transport Solutions, Scania Cv Ab, Södertälje, Sweden.
    Wahlberg, Bo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Reglerteknik.
    A Geometric Approach to On-road Motion Planning for Long and Multi-Body Heavy-Duty Vehicles2020Inngår i: 31st IEEE Intelligent Vehicles Symposium, IV 2020, 19 October 2020 - 13 November 2020, Institute of Electrical and Electronics Engineers (IEEE) , 2020, s. 999-1006Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Driving heavy-duty vehicles, such as buses and tractor-trailer vehicles, is a difficult task in comparison to passenger cars. Most research on motion planning for autonomous vehicles has focused on passenger vehicles, and many unique challenges associated with heavy-duty vehicles remain open. However, recent works have started to tackle the particular difficulties related to on-road motion planning for buses and tractor-trailer vehicles using numerical optimization approaches. In this work, we propose a framework to design an optimization objective to be used in motion planners. Based on geometric derivations, the method finds the optimal trade-off between the conflicting objectives of centering different axles of the vehicle in the lane. For the buses, we consider the front and rear axles trade-off, whereas for articulated vehicles, we consider the tractor and trailer rear axles trade-off. Our results show that the proposed design strategy produces planned paths that considerably improve the behavior of heavy-duty vehicles by keeping the whole vehicle body in the center of the lane.

  • 38621.
    Oliveira, Rui Filipe De Sousa
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Reglerteknik.
    Ljungqvist, Oskar
    Division of Automatic Control, Department of Electrical Engineering, Linköping University.
    Lima, Pedro F.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Reglerteknik.
    Wahlberg, Bo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Intelligenta system, Reglerteknik.
    Optimization-Based On-Road Path Planning for Articulated Vehicles2020Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Maneuvering an articulated vehicle on narrow road stretches is often a challenging task for a human driver. Unless the vehicle is accurately steered, parts of the vehicle’s bodies may exceed its assigned drive lane, resulting in an increased risk of collision with surrounding traffic. In this work, an optimization-based path-planning algorithm is proposed targeting on-road driving scenarios for articulated vehicles composed of a tractor and a trailer. To this end, we model the tractor-trailer vehicle in a road-aligned coordinate frame suited for on-road planning. Based on driving heuristics, a set of different optimization objectives is proposed, with the overall goal of designing a path planner that computes paths which minimize the off-track of the vehicle bodies swept area, while remaining on the road and avoiding collision with obstacles. The proposed optimization-based path-planning algorithm, together with the different optimization objectives, is evaluated and analyzed in simulations on a set of complicated and practically relevant on-road planning scenarios using the most challenging tractor-trailer dimensions.

  • 38622.
    Oliveri, Matteo
    et al.
    Univ Genoa, DITEN, Genoa, Italy..
    Baalsrud Hauge, Jannicke
    KTH, Skolan för industriell teknik och management (ITM), Hållbar produktionsutveckling (ML).
    Bellotti, Francesco
    Univ Genoa, DITEN, Genoa, Italy..
    Berta, Riccardo
    Univ Genoa, DITEN, Genoa, Italy..
    De Gloria, Alessandro
    Univ Genoa, DITEN, Genoa, Italy..
    Designing an IoT-focused, Multiplayer Serious Game for Industry 4.0 Innovation2019Inngår i: 2019 IEEE INTERNATIONAL CONFERENCE ON ENGINEERING, TECHNOLOGY AND INNOVATION (ICE/ITMC), IEEE , 2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    There is a trend in industries towards adoption of new technologies coming from Industry 4.0 to improve operational automation, efficiency, maintenance, by interconnecting sensors, devices, machines, and processes, increasing data availability for automation and decision support. These changing scenarios need to be addressed also in terms of instruction and training, for students, workers and stakeholders. In this paper, we explore as a case study the design of a Serious Game aimed at preparing undergraduate students to understand and cope with such new concepts, tools and practices, with a focus on the Internet of Things.

  • 38623.
    Oljira, Dejene Boru
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Taheri, Javid
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Analysis of Network Latency in Virtualized Environments2016Inngår i: Global Communications Conference (GLOBECOM), 2016 IEEE, IEEE, 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Virtualization is central to cloud computing systems. It abstracts computing resources to be shared among multiple virtual machines (VMs) that can be easily managed to run multiple applications and services. To benefit from the advantages of cloud computing, and to cope with increasing traffic demands, telecom operators have adopted cloud computing. Telecom services and applications are, however, characterized by real-time responsiveness, strict end-to-end latency, and high reliability. Due to the inherent overhead of virtualization, the network performance of applications and services can be degraded. To improve the performance of emerging applications and services that demand stringent end-to-end latency, and to understand the network performance bottleneck of virtualization, a comprehensive performance measurement and analysis is required. To this end, we conducted controlled and detailed experiments to understand the impact of virtualization on end-to-end latency and the performance of transport protocols in a virtualized environment. We also provide a packet delay breakdown in the virtualization layer which helps in the optimization of hypervisor components. Our experimental results indicate that the end-to-end latency and packet delay in the virtualization layer are increased with co-located VMs.

  • 38624.
    Oljira, Dejene Boru
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Taheri, Javid
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Validating the Sharing Behavior and Latency Characteristics of the L4S Architecture2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Internet services such as virtual reality, interactive cloud applications, and online gaming, have a strict quality of service requirements (e.g., low-latency). However, the current Internet is not able to satisfy the low-latency requirements of these applications. This as the standard TCP induces high queuing delays when used by capacity-seeking traffic, which in turn results in unpredictable latency. The Low Latency Low Loss Scalable throughput (L4S) architecture aims to address this problem by combining scalable congestion controls (e.g., DCTCP) with early congestion signaling from the network. For incremental deployment, the L4S architecture defines a Dual Queue Coupled AQM that enables the safe coexistence of scalable and classic (e.g., Reno, Cubic, etc.) flows on the global Internet. The DualPI2 AQM is a Linux kernel implementation of a Dual Queue Coupled AQM. In this paper, we benchmark the DualPI2 AQM to validate experimental result(s) reported in previous works that demonstrate the coexistence of scalable and classic congestion controls, and its low-latency service. Our results validate the coexistence of scalable and classic flows using DualPI2 single queue AQM while the result with dual queue shows neither rate nor window fairness between the flows.

  • 38625.
    Oljira, Dejene Boru
    et al.
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Grinnemo, Karl-Johan
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Taheri, Javid
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    Brunström, Anna
    Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), Institutionen för matematik och datavetenskap (from 2013).
    A Model for QoS-Aware VNF Placement and Provisioning2017Inngår i: Network Function Virtualization and Software Defined Networks (NFV-SDN), 2017 IEEE Conference on / [ed] IEEE, IEEE, 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Network Function Virtualization (NFV) is a promising solution for telecom operators and service providers to improve business agility, by enabling a fast deployment of new services, and by making it possible for them to cope with the increasing traffic volume and service demand. NFV enables virtualization of network functions that can be deployed as virtual machines on general purpose server hardware in cloud environments, effectively reducing deployment and operational costs. To benefit from the advantages of NFV, virtual network functions (VNFs) need to be provisioned with sufficient resources and perform without impacting network quality of service (QoS). To this end, this paper proposes a model for VNFs placement and provisioning optimization while guaranteeing the latency requirements of the service chains. Our goal is to optimize resource utilization in order to reduce cost satisfying the QoS such as end- to-end latency. We extend a related VNFs placement optimization with a fine-grained latency model including virtualization overhead. The model is evaluated with a simulated network and it provides placement solutions ensuring the required QoS guarantees. 

  • 38626.
    Ollander, Simon
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik.
    Wearable Sensor Data Fusion for Human Stress Estimation2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    With the purpose of classifying and modelling stress, different sensors, signal features, machine learning methods, and stress experiments have been compared. Two databases have been studied: the MIT driver stress database and a new experimental database, where three stress tasks have been performed for 9 subjects: the Trier Social Stress Test, the Socially Evaluated Cold Pressor Test and the d2 test, of which the latter is not classically used for generating stress. Support vector machine, naive Bayes, k-nearest neighbor and probabilistic neural network classification techniques were compared, with support vector machines achieving the highest performance in general (99.5 ±0.6 %$on the driver database and 91.4 ± 2.4 % on the experimental database). For both databases, relevant features include the mean of the heart rate and the mean of the galvanic skin response, together with the mean of the absolute derivative of the galvanic skin response signal. A new feature is also introduced with great performance in stress classification for the driver database. Continuous models for estimating stress levels have also been developed, based upon the perceived stress levels given by the subjects during the experiments, where support vector regression is more accurate than linear and variational Bayesian regression.

    Fulltekst (pdf)
    Wearable Sensor Data Fusion for Human Stress Estimation
  • 38627.
    Ollars, Emil
    Luleå tekniska universitet, Institutionen för system- och rymdteknik.
    Design and characterization of a radio receiver for satellite communication2021Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Due to the increase in volume and speed of data transmissions in recent years, the demand for high-speed satellite communication solutions has increased. This thesis investigates the possibility of making a receiver for satellite radio based on an Analog Devices ADC evaluation board. To do this, evaluation boards for each component were acquired and tested individually before connecting them. The system components include an I/Q demodulator, a local oscillator, and an ADC. Using these components a system design for the radio receiver has been proposed, and its performance analyzed. The SNR of the designed system was measured to26 dB. This performance was deemed to be sufficient for a signal using the BPSKmodulation scheme.

    Fulltekst (pdf)
    fulltext
  • 38628.
    Ollas, Patrik
    RISE Research Institutes of Sweden, Samhällsbyggnad, Energi och resurser. Chalmers University of Technology, Sweden.
    Energy Savings Using a Direct Current Distribution Network in a PV and Battery Equipped Residential Building2020Licentiatavhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Energy from solar photovoltaic (PV) are generated as direct current (DC) and almost all of today’s electrical loads in residential buildings, household appliances and HVAC system (Heating Ventilation and Air-conditioning) are operated on DC. For a conventional alternating current (AC) distribution system this requires the need for multiple conversion steps before the final user-stage. By switching the distribution system to DC, conversion steps between AC to DC can be avoided and, in that way, losses are reduced. Including a battery storage–the system’s losses can be reduced further and the generated PV energy is even better utilised.

    This thesis investigates and quantifies the energy savings when using a direct current distribution topology in a residential building together with distributed energy generation from solar photovoltaic and a battery storage. Measured load and PV generation data for a single-family house situated in Borås, Sweden is used as a case study for the analysis. Detailed and dynamic models–based on laboratory measurements of the power electronic converters and the battery–are also used to more accurately reflect the system’s dynamic performance.

    In this study a dynamic representation of the battery’s losses is presented which is based on laboratory measurements of the resistance and current dependency for a single lithium-ion cell based on Lithium iron phosphate (LFP). A comparative study is made with two others, commonly used, loss representations and evaluated with regards to the complete system’s performance, using the PV and load data from the single-family house. Results show that a detailed battery representation is important for a correct loss prediction when modelling the interaction between loads, PV and the battery.

    Four DC system topologies are also modelled and compared to an equivalent AC topology using the experimental findings from the power electronic converters and the battery measurements. Results from the quasi-dynamic modelling show that the annual energy savings potential from the suggested DC topologies ranges between 1.9–5.6%. The DC topologies also increase the PV utilisation by up to 10 percentage points, by reducing the associated losses from the inverter and the battery conversion. Results also show that the grid-tied converter is the main loss contributor and when a constant grid-tied efficiency is used, the energy savings are overestimated.

    Fulltekst (pdf)
    Licentiatavhandling__OLLAS
  • 38629.
    Ollas, Patrik
    et al.
    RISE Research Institutes of Sweden, Samhällsbyggnad, Energi och resurser. Chalmers University of Technology, Sweden.
    Ghaem Sigarchian, Sara
    RISE Research Institutes of Sweden, Samhällsbyggnad, Energi och resurser.
    Alfredsson, Hampus
    RISE Research Institutes of Sweden, Digitala system, Mobilitet och system.
    Leijon, Jennifer
    Uppsala University, Sweden.
    Döhler, Jessica Santos
    Uppsala University, Sweden.
    Aalhuizen, Christoffer
    Uppsala University, Sweden.
    Thiringer, Torbjörn
    Chalmers University of Technology, Sweden.
    Thomas, Karin
    Uppsala University, Sweden.
    Evaluating the role of solar photovoltaic and battery storage in supporting electric aviation and vehicle infrastructure at Visby Airport2023Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 352, artikkel-id 121946Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Following the societal electrification trend, airports face an inevitable transition of increased electric demand, driven by electric vehicles (EVs) and the potential rise of electric aviation (EA). For aviation, short-haul flights are first in line for fuel exchange to electrified transportation. This work studies the airport of Visby, Sweden and the effect on the electrical power system from EA and EV charging. It uses the measured airport load demand from one year’s operation and simulated EA and EV charging profiles. Solar photovoltaic (PV) and electrical battery energy storage systems (BESS) are modelled to analyse the potential techno-economical gains. The BESS charge and discharge control are modelled in four ways, including a novel multi-objective (MO) dispatch to combine self-consumption (SC) enhancement and peak power shaving. Each model scenario is compared for peak power shaving ability, SC rate and pay-back-period (PBP). The BESS controls are also evaluated for annual degradation and associated cost. The results show that the novel MO dispatch performs well for peak shaving and SC, effectively reducing the BESS’s idle periods. The MO dispatch also results in the battery controls’ lowest PBP (6.9 years) using the nominal economic parameters. Furthermore, a sensitivity analysis for the PBP shows that the peak power tariff significantly influences the PBP for BESS investment. 

  • 38630.
    Ollas, Patrik
    et al.
    RISE Research Institutes of Sweden; Chalmers University of Technology.
    Ghaem Sigarchian, Sara
    RISE Research Institutes of Sweden.
    Alfredsson, Hampus
    RISE Research Institutes of Sweden.
    Leijon, Jennifer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för elektroteknik, Elektricitetslära.
    Santos Döhler, Jessica
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för elektroteknik, Elektricitetslära.
    Aalhuizen, Christoffer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för elektroteknik, Elektricitetslära.
    Thiringer, Torbjörn
    Chalmers University of Technology.
    Thomas, Karin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för elektroteknik, Elektricitetslära.
    Evaluating the role of solar photovoltaic and battery storage in supporting electric aviation and vehicle infrastructure at Visby Airport2023Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 352, artikkel-id 121946Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Following the societal electrification trend, airports face an inevitable transition of increased electric demand,driven by electric vehicles (EVs) and the potential rise of electric aviation (EA). For aviation, short-haul flightsare first in line for fuel exchange to electrified transportation. This work studies the airport of Visby, Sweden and the effect on the electrical power system from EA and EV charging. It uses the measured airport loaddemand from one year’s operation and simulated EA and EV charging profiles. Solar photovoltaic (PV) and electrical battery energy storage systems (BESS) are modelled to analyse the potential techno-economical gains.The BESS charge and discharge control are modelled in four ways, including a novel multi-objective (MO) dispatch to combine self-consumption (SC) enhancement and peak power shaving. Each model scenario iscompared for peak power shaving ability, SC rate and pay-back-period (PBP). The BESS controls are alsoevaluated for annual degradation and associated cost. The results show that the novel MO dispatch performswell for peak shaving and SC, effectively reducing the BESS’s idle periods. The MO dispatch also results in the battery controls’ lowest PBP (6.9 years) using the nominal economic parameters. Furthermore, a sensitivityanalysis for the PBP shows that the peak power tariff significantly influences the PBP for BESS investment.

    Fulltekst (pdf)
    fulltext
  • 38631.
    Ollas, Patrik
    et al.
    RISE Research Institutes of Sweden, Samhällsbyggnad, Energi och resurser.
    Markusson, Caroline
    RISE Research Institutes of Sweden, Samhällsbyggnad, Energi och resurser.
    Eriksson, Jörgen
    EQUA Solutions, Sweden.
    Chen, Huijuan
    RISE Research Institutes of Sweden, Samhällsbyggnad, Energi och resurser.
    Lindahl, Markus
    RISE Research Institutes of Sweden, Samhällsbyggnad, Energi och resurser.
    Thiringer, Torbjörn
    Chalmers University of Technology, Sweden.
    Quasi-Dynamic Modelling of DC Operated Ground-Source Heat Pump2020Inngår i: SINTEF Proceedings; 5, Oslo, 2020, Vol. 5, s. 208-213Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The performance of a conventional ground-source heat pump (GSHP) has been measured in the laboratory with alternating current (AC) and direct current(DC) operation using the standardised points fromEN14511:2018. The results from these measurements have been used to modify a variable speed heat pump model in IDA Indoor Climate and Energy (ICE) and the annual performance of AC and DC operation have been simulated for an entire year's operation at two geographical locations in Sweden. Results show that the energy savings with DC operation from laboratory measurements span between 1.4{5.2% and when simulating the performance for an entire year's operation, the energy savings vary between 2.5{3.4%. Furthermore, the energy savings from the simulations have been compared to the bin method described in EN14825:2018.

  • 38632.
    Ollas, Patrik
    et al.
    RISE Research Institutes of Sweden, Samhällsbyggnad, Energi och resurser.
    Thiringer, Torbjörn
    Chalmers University of Technology, Sweden.
    Chen, Huijuan
    RISE Research Institutes of Sweden, Samhällsbyggnad, Energi och resurser.
    Markusson, Caroline
    RISE Research Institutes of Sweden, Samhällsbyggnad, Energi och resurser.
    Increased PV Utilisation from DC Distribution: Quantification of Geographical Impact2020Inngår i: EU PVSEC Conference Proceedings, 2020, s. 1432-1441Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, the performance of a direct current (DC) distribution system is modelled and compared fora single-family residential building with a conventional alternating current (AC) system to quantify the potential energy savings and gains in PV utilization. The modelling is also made for two different climates to quantify the impact of the geographical location. Results show that the system losses are reduced by 19-46% and the PV utilization increased by 3.9-7.4% when using a DC distribution system compared to an AC equivalent, resulting in system efficiency gains in the range of 1.3-8.8%. Furthermore, it is shown that the geographical location has some effect on the system's performance and PV utilization, but most importantly the grid interaction is paramount for the performance of the DC topology.

  • 38633.
    Ollas, Patrik
    et al.
    RISE Research Institutes of Sweden, Samhällsbyggnad, Energi och resurser. Chalmers University of Technology, Sweden.
    Thiringer, Torbjörn
    Chalmers University of Technology, Sweden.
    Persson, Mattias
    RISE Research Institutes of Sweden, Säkerhet och transport, Mätteknik.
    Markusson, Caroline
    RISE Research Institutes of Sweden, Samhällsbyggnad, Energi och resurser.
    Battery loss prediction using various loss models: A case study for a residential building2023Inngår i: Journal of Energy Storage, ISSN 2352-152X, E-ISSN 2352-1538, Vol. 70, artikkel-id 108048Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work compares and quantifies the annual losses for three battery system loss representations in a case study for a residential building with solar photovoltaic (PV). Two loss representations consider the varying operating conditions and use the measured performance of battery power electronic converters (PECs) but differ in using either a constant or current-dependent internal battery cell resistance. The third representation is load-independent and uses a (fixed) round trip efficiency. The work uses sub-hourly measurements of the load and PV profiles and includes the results from varying PV and battery size combinations. The results reveal an inadequacy of using a constant battery internal resistance and quantify the annual loss discrepancy to −38.6%, compared to a case with current-dependent internal resistance. The results also show the flaw of modelling the battery system’s efficiency with a fixed round trip efficiency, with loss discrepancy variation between −5 to 17% depending on the scenario. Furthermore, the necessity of accounting for the cell’s loss is highlighted, and its dependence on converter loading is quantified.

    Fulltekst (pdf)
    fulltext
  • 38634.
    Ollesson, Niklas
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska högskolan.
    Automatic Configuration of Vision Sensor2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In factory automation cameras and image processing algorithms can be used to inspect objects. This can decrease the faulty objects that leave the factory and reduce manual labour needed. A vision sensor is a system where camera and image processing is delivered together, and that only needs to be configured for the application that it is to be used for. Thus no programming knowledge is needed for the customer. In this Master’s thesis a way to make the configuration of a vision sensor even easier is developed and evaluated.

    The idea is that the customer knows his or her product much better than he or she knows image processing. The customer could take images of positive and negative samples of the object that is to be inspected. The algorithm should then, given these images, configure the vision sensor automatically.

    The algorithm that is developed to solve this problem is described step by step with examples to illustrate the problems that needed to be solved. Much of the focus is on how to compare two configurations to each other, in order to find the best one. The resulting configuration from the algorithm is then evaluated with respect to types of applications, computation time and representativeness of the input images.

    Fulltekst (pdf)
    fulltext
  • 38635.
    Ollila, Mark
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    Special Effects and Rendering: Proceedings from SIGRAD 2002, Linköpings universitet, Norrköping, Sweden, November 28th and 29th, 20022002Konferanseproceedings (Fagfellevurdert)
    Fulltekst (pdf)
    Special Effects and Rendering: Proceedings from SIGRAD 2002, Linköpings universitet, Norrköping, Sweden, November 28th and 29th, 2002
    Download (pdf)
    omslag
    Download (jpg)
    presentationsbild
  • 38636.
    Olmedilla, Carlos Hernandez Matas and Diana Gomez
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    Image Theory Applied to virtual Microphones2008Independent thesis Basic level (degree of Bachelor)Oppgave
    Abstract [en]

    Virtual sensing is the art of measuring a quantity at a certain spatial position without having a physical sensor placed at that exact same position. In practical applications, this technique is sometimes very useful, when it is not feasible to put the sensor at the position where the physical quantity should be measured. For example, a virtual microphone could be considered in the following scenario: The sound level, preliminary school environment, should be studied at the different students head positions. In order to get statistical relevant data, the measurement has to be carried out over a period of time. However, it is not a feasible approach to use a large number of microphones hanging from the ceiling at the students head level, over a longer period of time for obvious reasons. One thoughtful solution, in such a situation is to put microphones at the walls and close to the ceiling and using the virtual technique to calculate the noise level at the students head positions based on the measure data. An advantage in such large setup is that it often requires less physical sensors than the number of virtual measurement positions and at the same time features a better validation and sanity check of the data. The most popular application areas for virtual microphones are in active noise control (ANC) or active structural acoustic control (ASAC), where the aim is to move the zone of quietness away from the physical error microphones to the desired location of maximum attenuation. However, there is an important difference between virtual sensing for active control and virtual sensing for a pure measurement situation concerning the delays introduced by virtual sensing technique. This specific thesis work deals with the calculus of all the possible paths and reflections followed by a sound wave between the source and a given destination point, by using virtual transducers in an enclosed environment where reverberation exists. The aim of this work is to determine how to calculate that impulse response in a rectangular room in which the walls have uniform reflection coefficients and there isn’t any kind of furniture inside. Besides, this project specifies a simple way to make this calculus taking into account several sources and destinations.

    Fulltekst (pdf)
    FULLTEXT01
  • 38637. Olmos, JJ Vegas
    et al.
    Pang, Xiaodan
    Technical University of Denmark, Denmark.
    Lebedev, Alexander
    Monroy, I Tafur
    VCSEL sources for optical fiber-wireless composite data links at 60GHz2013Inngår i: 2013 18th OptoElectronics and Communications Conference Held Jointly with 2013 International Conference on Photonics in Switching, OECC/PS 2013, 2013, artikkel-id 6597583Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents a performance assessment of 60-GHz mm-wave signal generation using photonic upconversion employing a VCSEL as source. The system reaches 10-9 BER over a variety of optical fibers for data rates of 1.25-Gbit/s.

  • 38638. Olmos, JJ Vegas
    et al.
    Pang, Xiaodan
    RISE ACREO AB; Technical University of Denmark.
    Lebedev, Alexander
    Sales, M.
    Monroy, Idelfonso Tafur
    Wireless and wireline service convergence in next generation optical access networks-the FP7 WISCON project2014Inngår i: IEICE transactions on communications, ISSN 0916-8516, E-ISSN 1745-1345, Vol. 97, nr 8, s. 1537-1546Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The next generation of information technology demands both high capacity and mobility for applications such as high speed wireless access capable of supporting broadband services. The transport of wireless and wireline signals is converging into a common telecommunication infrastructure. In this paper, we will present the Marie Curie Framework Program 7 project "Wireless and wireline service convergence in next generation optical access networks" (WISCON), which focuses on the conception and study of novel architectures for wavelength-division-multiplexing (WDM) optical multi-modulation format radio-over-fiber (RoF) systems; this is a promising solution to implement broadband seamless wireless wireline access networks. This project successfully concluded in autumn 2013, and is being follow up by another Marie Curie project entitled "flexible edge nodes for dynamic optical interconnection of access and core networks" (FENDOI), which will be also briefly described.

  • 38639. Olmos, JJ Vegas
    et al.
    Pang, Xiaodan
    RISE ACREO AB; Technical University of Denmark.
    Monroy, I Tafur
    E-and W-Band High-Capacity Hybrid Fiber-Wireless Links2014Inngår i: IEICE transactions on communications, ISSN 0916-8516, E-ISSN 1745-1345, Vol. 97, nr 7, s. 1290-1294Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper we summarize the work conducted in our group in the area of E- and W-band optical high-capacity fiber-wireless links. We present performance evaluations of E- and W-band mm-wave signal generation using photonic frequency upconversion employing both VCSELs and ECLs, along with transmission over different type of optical fibers and for a number of values for the wireless link distance. Hybrid wireless-optical links can be composed of mature and resilient technology available off-the-shelf, and provide functionalities that can add value to optical access networks, specifically in mobile backhaul/fronthaul applications, dense distributed antenna systems and fiber-over-radio scenarios.

  • 38640. Olmos, Juan José Vegas
    et al.
    Pang, Xiaodan
    Technical University of Denmark.
    Lebedev, Alexander
    Monroy, Idelfonso Tafur
    Multi-Gigabit Capacity W-band Hybrid Wireless-Photonic Transmission Link2013Inngår i: Asia Communications and Photonics Conference, Optical Society of America, 2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present a 10-meter bidirectional fiber-wireless-fiber system at 81/86-GHz (Wband). The fiber transmission amounts for 36-km, whereas the wireless transmission for 10-m, achieving BER performance below the 7% FEC limit for both downstream and upstream.

  • 38641.
    Olnén, Johanna
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Sommarlund, Julia
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Activity Recognition Using IoT and Machine Learning2020Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Internet of Things devices, such as smartphonesand smartwatches, are currently becoming widely accessible andprogressively advanced. As the use of these devices steadilyincreases, so does the access to large amounts of sensory data.In this project, we developed a system that recognizes certainactivities by applying a linear classifier machine learning modelto a data set consisting of examples extracted from accelerometersensor data. We obtained the data set by collecting data from amobile device while performing commonplace everyday activities.These activities include walking, standing, driving, and ridingthe subway. The raw accelerometer data was then aggregatedinto data points, consisting of several informative features. Thecomplete data set was subsequently split into 80% training dataand 20% test data. A machine learning algorithm, in this case,a support vector machine, was presented with the training dataset and finally classified all test data with a precision higher than90%. Hence, meeting our set objective to build a service with acorrect classification score of over 90%.Human activity recognition has a large area of application,including improved health-related recommendations and a moreefficiently engineered system for public transportation.

    Fulltekst (pdf)
    fulltext
  • 38642.
    Olof, Ahlgren Bergström
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Adaptive detection of anomalies in fuel system of Saab 39 Gripen using machine learning: Investigating methods to improve anomaly detection of selected signals in the fuel system of Gripen E.2022Independent thesis Advanced level (degree of Master (Two Years)), 28 hpOppgave
    Abstract [en]

    The process of flying fighter jets naturally comes with tough environments and manoeu-vres where temperatures, pressures and forces all have a large impact on the aircraft. Part degeneration and general wear and tear greatly affects functionalities of the aircraft, and it is of importance to carefully monitor the well being of an aircraft in order to avoid catastrophic accidents. Therefore, this project aims to investigate various ways to improve anomaly detection of selected signals in the Gripen E fuel system. The methodology in this project was to compare collected flight data with generated data of a simulation model. The method was conducted for three selected signals with different properties, namely the transfer pump outlet pressure and flow, as well as the fuel mass in tank 2. A neural network was trained to generate predictions of the residual between measured and simulated flight data, together with a RandomForestRegressor to create a confidence interval of said signal. This made it possible to detect signal abnormalities when the gathered flight data heavily deviated from the generated machine learning algorithm predictions, thus alarming for anomalies.

    Investigated methods to improve anomaly detection includes feature selection, adding ar-tificial signals to facilitate machine learning algorithm training and filtering. A large part was also to see how an improved simulation model, and thus more accurate simulation data would affect the anomaly detection. A lot of effort was put into improving the simulation model, and investigating this area. In addition to this, the data balancing and features to balance the data on was revised. A significant challenge to tackle in this project was to map the modelling difficulties due to differences in signal properties. A by-productof improving the anomaly detection was that a general method was obtained to create a anomaly detection model of an arbitrarily chosen signal in the fuel system, regardless of the signal properties.

    Results show that the anomaly detection model was improved, with the main improvement area shown to be the choice of features. Improving the simulation model did not improve the anomaly detection in the transfer pump outlet pressure and flow, but it did however slightly facilitate anomaly detection of the fuel mass in tank 2 signal. It is also concluded that the signal properties can greatly affect the anomaly detection models, as accumulated effects in a signal can complicate anomaly detection. Remaining improvement areas such as filtering and addition of artificial signals can be helpful but needs to be looked into for each signal. It was also concluded that a stochastic behaviour was seen in the data balancing process, that could skew results if not handled properly. Over all the three selected signals, only one flight was misclassified as an anomaly, which can be seen as great results.  

    Fulltekst (pdf)
    fulltext
  • 38643.
    Olof, Nilsson
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Short Term Scheduling of Hydrothermal Power Systems With Integer Hydro Constraints1997Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    The thesis presents models for short term planning (24 hours) of a hyro dominated hydrothermal power system. The purpose of the models is to minimizae the system operation costs to provide a forecasted load and keep enough spinning reserve.

    Fulltekst (pdf)
    fulltext
  • 38644.
    Olof, S
    et al.
    KTH, Skolan för elektro- och systemteknik (EES).
    Forsberg, A
    KTH, Skolan för elektro- och systemteknik (EES).
    Torres Merkoulova, Daniel
    KTH, Skolan för elektro- och systemteknik (EES).
    Tamilselva, Kruphalan
    KTH, Skolan för elektro- och systemteknik (EES).
    Non-contact Current Measurement of Power Transmission Lines2015Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Fulltekst (pdf)
    fulltext
  • 38645.
    Olofsson, Andreas
    et al.
    Adapteva Inc., Lexington, MA, USA.
    Nordström, Tomas
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Ul-Abdin, Zain
    Högskolan i Halmstad, Akademin för informationsteknologi, Halmstad Embedded and Intelligent Systems Research (EIS), Centrum för forskning om inbyggda system (CERES).
    Kickstarting High-performance Energy-efficient Manycore Architectures with Epiphany2014Inngår i: Conference record: Forty-Eighth Asilomar Conference on Signals, Systems & Computers, November 2-5, 2014, Pacific Grove, California / [ed] Michael B. Matthews, Piscataway, NJ: IEEE Press, 2014, s. 1719-1726Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we introduce Epiphany as a high-performance energy-efficient manycore architecture suitable for real-time embedded systems. This scalable architecture supports floating point operations in hardware and achieves 50 GFLOPS/W in 28 nm technology, making it suitable for high performance streaming applications like radio base stations and radar signal processing. Through an efficient 2D mesh Network-on-Chip and a distributed shared memory model, the architecture is scalable to thousands of cores on a single chip. An Epiphany-based open source computer named Parallella was launched in 2012 through Kickstarter crowd funding and has now shipped to thousands of customers around the world. ©2014 IEEE.

  • 38646.
    Olofsson, Anthon
    Luleå tekniska universitet, Institutionen för system- och rymdteknik.
    Att skapa en plattformsoberoende applikation med bra användarupplevelse2019Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Fulltekst (pdf)
    fulltext
  • 38647.
    Olofsson, Bjorn
    et al.
    Lund University, Sweden.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Path-tracking velocity control for robot manipulators with actuator constraints2017Inngår i: Mechatronics (Oxford), ISSN 0957-4158, E-ISSN 1873-4006, Vol. 45, s. 82-99Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An algorithm for high-performance path tracking for robot manipulators in the presence of model uncertainties and actuator constraints is presented. The path to be tracked is assumed given, and the nominal trajectories are computed using, for example, well-known algorithms for time-optimal path tracking. For online path tracking, the nominal, feedforward trajectories are combined with feedback in a control architecture with a secondary controller, such that robustness to uncertainties in model or environment is achieved. The control law is based on existing path-velocity control (PVC), or so called online time scaling, but in addition to speed adaptation along the tangent of the path, the algorithm also comprises an explicit formulation and approach, with several attractive properties, for handling the deviations along the transversal directions of the path. For achieving fast convergence along the normal and binormal directions of the path in 3D motion, the strategy proposed has inherent exponential convergence properties. The result is a complete architecture for path-tracking velocity control (PTVC). The method is evaluated in extensive simulations with manipulators of different complexity, and PTVC exhibits superior performance compared to PVC. (C) 2017 Elsevier Ltd. All rights reserved.

  • 38648.
    Olofsson, Björn
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Using Crash Databases to Predict Effectiveness of New Autonomous Vehicle Maneuvers for Lane-Departure Injury Reduction2021Inngår i: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 22, nr 6, s. 3479-3490Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Autonomous vehicle functions in safety-critical situations show promise in reducing the risk and saving lives in accidents compared to existing safety systems. Consequently, it is from many perspectives advantageous to be able to quantify the potential benefits of new autonomous systems for vehicle maneuvers at-the-limit of tire friction. Here, to estimate the potential in terms of saved lives and reduced degree of injuries in accidents for new, not yet existing systems, a framework has been developed by combining available historic data, in the form of crash databases, and statistical methods with comparative calculations of vehicle behavior using numerical optimization rather than simulation. The framework performs effectively, it gives interesting insights into the relation between more traditional active yaw control and optimal autonomous lane-keeping control, and it clearly demonstrates the potential of saved lives by using autonomous vehicle maneuvers.

    Fulltekst (pdf)
    fulltext
  • 38649.
    Olofsson, Daniel
    Luleå tekniska universitet, Institutionen för system- och rymdteknik.
    Täckningsmätning och verktygsutveckling för LoRa2018Independent thesis Basic level (university diploma), 5 poäng / 7,5 hpOppgave
    Fulltekst (pdf)
    fulltext
  • 38650.
    Olofsson, Didrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för elektroteknik, Signaler och system.
    OBD-II monitor using smartphone and cloud solutions: For ECO driving2022Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Fuel consumption of transportation vehicles account for nearly 27% of CO2 emissions from fossil fuel. The environmental impact of of transportation can be lowered with effective ECOfriendly driving. As modern vehicles are equipped with the on-board diagnostics (OBD) system that provides vehicle’s self-diagnostic data which is accessible to from the OBD-II socket in vehicles.

    The aim of this thesis is to design and implement such a monitor system that consists of an OBD-II reader (containing a Bluetooth communication module) to fetch data from the OBD-II socket and then, via a smartphone, send the data to a cloud server for analysis and visualisation. For this purpose, an ELM327 Bluetooth module (an off-the-shelf OBD-II dongle) was bought, an application has been created for an Android smartphone, and a cloud server has been created using ThinkSpeak (an online solution for cloud data collection and visualisation).

      As a result, such monitor system has been implemented at low cost, and then tested and evaluated together with a Toyota Prius driving a round-trip between the Swedish cities of Uppsala and Arlanda. The test results have shown that the system is successful in gathering data from the OBD-II socket and then sending visualizing data.

    It needs, however, further work to increase the user-friendliness and accuracy of the gathered information from the vehicle.

    Fulltekst (pdf)
    MasterThisis OBD-II monitor
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