Collaborative autonomy in heterogeneous multi-robot systems

As autonomous mobile robots become increasingly connected and widely deployed in different domains, managing multiple robots and their interaction is key to the future of ubiquitous autonomous systems. Indeed, robots are not individual entities anymore. Instead, many robots today are deployed as part of larger fleets or in teams. The benefits of multirobot collaboration, specially in heterogeneous groups, are multiple. Significantly higher degrees of situational awareness and understanding of their environment can be achieved when robots with different operational capabilities are deployed together. Examples of this include the Perseverance rover and the Ingenuity helicopter that NASA has deployed in Mars, or the highly heterogeneous robot teams that explored caves and other complex environments during the last DARPA Sub-T competition. This thesis delves into the wide topic of collaborative autonomy in multi-robot systems, encompassing some of the key elements required for achieving robust collaboration: solving collaborative decision-making problems; securing their operation, management and interaction; providing means for autonomous coordination in space and accurate global or relative state estimation; and achieving collaborative situational awareness through distributed perception and cooperative planning. The thesis covers novel formation control algorithms, and new ways to achieve accurate absolute or relative localization within multi-robot systems. It also explores the potential of distributed ledger technologies as an underlying framework to achieve collaborative decision-making in distributed robotic systems. Throughout the thesis, I introduce novel approaches to utilizing cryptographic elements and blockchain technology for securing the operation of autonomous robots, showing that sensor data and mission instructions can be validated in an end-to-end manner. I then shift the focus to localization and coordination, studying ultra-wideband (UWB) radios and their potential. I show how UWB-based ranging and localization can enable aerial robots to operate in GNSS-denied environments, with a study of the constraints and limitations. I also study the potential of UWB-based relative localization between aerial and ground robots for more accurate positioning in areas where GNSS signals degrade. In terms of coordination, I introduce two new algorithms for formation control that require zero to minimal communication, if enough degree of awareness of neighbor robots is available. These algorithms are validated in simulation and real-world experiments. The thesis concludes with the integration of a new approach to cooperative path planning algorithms and UWB-based relative localization for dense scene reconstruction using lidar and vision sensors in ground and aerial robots

Trace-based Performance Analysis for Hardware Accelerators

This thesis presents how performance data from hardware accelerators can be included in event logs. It extends the capabilities of trace-based performance analysis to also monitor and record data from this novel parallelization layer. The increasing awareness to power consumption of computing devices has led to an interest in hybrid computing architectures as well. High-end computers, workstations, and mobile devices start to employ hardware accelerators to offload computationally intense and parallel tasks, while at the same time retaining a highly efficient scalar compute unit for non-parallel tasks. This execution pattern is typically asynchronous so that the scalar unit can resume other work while the hardware accelerator is busy. Performance analysis tools provided by the hardware accelerator vendors cover the situation of one host using one device very well. Yet, they do not address the needs of the high performance computing community. This thesis investigates ways to extend existing methods for recording events from highly parallel applications to also cover scenarios in which hardware accelerators aid these applications. After introducing a generic approach that is suitable for any API based acceleration paradigm, the thesis derives a suggestion for a generic performance API for hardware accelerators and its implementation with NVIDIA CUPTI. In a next step the visualization of event logs containing data from execution streams on different levels of parallelism is discussed. In order to overcome the limitations of classic performance profiles and timeline displays, a graph-based visualization using Parallel Performance Flow Graphs (PPFGs) is introduced. This novel technical approach is using program states in order to display similarities and differences between the potentially very large number of event streams and, thus, enables a fast way to spot load imbalances. The thesis concludes with the in-depth analysis of a case-study of PIConGPU---a highly parallel, multi-hybrid plasma physics simulation---that benefited greatly from the developed performance analysis methods.Diese Dissertation zeigt, wie der Ablauf von Anwendungsteilen, die auf Hardwarebeschleuniger ausgelagert wurden, als Programmspur mit aufgezeichnet werden kann. Damit wird die bekannte Technik der Leistungsanalyse von Anwendungen mittels Programmspuren so erweitert, dass auch diese neue Parallelitätsebene mit erfasst wird. Die Beschränkungen von Computersystemen bezüglich der elektrischen Leistungsaufnahme hat zu einer steigenden Anzahl von hybriden Computerarchitekturen geführt. Sowohl Hochleistungsrechner, aber auch Arbeitsplatzcomputer und mobile Endgeräte nutzen heute Hardwarebeschleuniger um rechenintensive, parallele Programmteile auszulagern und so den skalaren Hauptprozessor zu entlasten und nur für nicht parallele Programmteile zu verwenden. Dieses Ausführungsschema ist typischerweise asynchron: der Skalarprozessor kann, während der Hardwarebeschleuniger rechnet, selbst weiterarbeiten. Die Leistungsanalyse-Werkzeuge der Hersteller von Hardwarebeschleunigern decken den Standardfall (ein Host-System mit einem Hardwarebeschleuniger) sehr gut ab, scheitern aber an einer Unterstützung von hochparallelen Rechnersystemen. Die vorliegende Dissertation untersucht, in wie weit auch multi-hybride Anwendungen die Aktivität von Hardwarebeschleunigern aufzeichnen können. Dazu wird die vorhandene Methode zur Erzeugung von Programmspuren für hochparallele Anwendungen entsprechend erweitert. In dieser Untersuchung wird zuerst eine allgemeine Methodik entwickelt, mit der sich für jede API-gestützte Hardwarebeschleunigung eine Programmspur erstellen lässt. Darauf aufbauend wird eine eigene Programmierschnittstelle entwickelt, die es ermöglicht weitere leistungsrelevante Daten aufzuzeichnen. Die Umsetzung dieser Schnittstelle wird am Beispiel von NVIDIA CUPTI darstellt. Ein weiterer Teil der Arbeit beschäftigt sich mit der Darstellung von Programmspuren, welche Aufzeichnungen von den unterschiedlichen Parallelitätsebenen enthalten. Um die Einschränkungen klassischer Leistungsprofile oder Zeitachsendarstellungen zu überwinden, wird mit den parallelen Programmablaufgraphen (PPFGs) eine neue graphenbasisierte Darstellungsform eingeführt. Dieser neuartige Ansatz zeigt eine Programmspur als eine Folge von Programmzuständen mit gemeinsamen und unterchiedlichen Abläufen. So können divergierendes Programmverhalten und Lastimbalancen deutlich einfacher lokalisiert werden. Die Arbeit schließt mit der detaillierten Analyse von PIConGPU -- einer multi-hybriden Simulation aus der Plasmaphysik --, die in großem Maße von den in dieser Arbeit entwickelten Analysemöglichkeiten profiert hat

Fundamentals

Volume 1 establishes the foundations of this new field. It goes through all the steps from data collection, their summary and clustering, to different aspects of resource-aware learning, i.e., hardware, memory, energy, and communication awareness. Machine learning methods are inspected with respect to resource requirements and how to enhance scalability on diverse computing architectures ranging from embedded systems to large computing clusters

Mobile Oriented Future Internet (MOFI)

This Special Issue consists of seven papers that discuss how to enhance mobility management and its associated performance in the mobile-oriented future Internet (MOFI) environment. The first two papers deal with the architectural design and experimentation of mobility management schemes, in which new schemes are proposed and real-world testbed experimentations are performed. The subsequent three papers focus on the use of software-defined networks (SDN) for effective service provisioning in the MOFI environment, together with real-world practices and testbed experimentations. The remaining two papers discuss the network engineering issues in newly emerging mobile networks, such as flying ad-hoc networks (FANET) and connected vehicular networks

Fundamentals

Volume 1 establishes the foundations of this new field. It goes through all the steps from data collection, their summary and clustering, to different aspects of resource-aware learning, i.e., hardware, memory, energy, and communication awareness. Machine learning methods are inspected with respect to resource requirements and how to enhance scalability on diverse computing architectures ranging from embedded systems to large computing clusters

Novel Charging and Discharging Schemes for Electric Vehicles in Smart Grids

PhD ThesisThis thesis presents smart Charging and Discharging (C&D) schemes in the smart grid that enable a decentralised scheduling with large volumes of Electric Vehicles (EV) participation. The proposed C&D schemes use di erent strategies to atten the power consumption pro le by manipulating the charging or discharging electricity quantity. The novelty of this thesis lies in: 1. A user-behaviour based smart EV charging scheme that lowers the overall peak demand with an optimised EV charging schedule. It achieves the minimal impacts on users' daily routine while satisfying EV charging demands. 2. A decentralised EV electricity exchange process matches the power demand with an adaptive blockchain-enabled C&D scheme and iceberg order execution algorithm. It demonstrates improved performance in terms of charging costs and power consumption pro le. 3. The Peer-to-Peer (P2P) electricity C&D scheme that stimulates the trading depth and energy market pro le with the best price guide. It also increases the EV users' autonomy and achieved maximal bene ts for the network peers while protecting against potential attacks. 4. A novel consensus-mechanism driven EV C&D scheme for the blockchain-based system that accommodates high volume EV scenarios and substantially reduces the power uctuation level. The theoretical and comprehensive simulations prove that the penetration of EV with the proposed schemes minimises the power uctuation level in an urban area, and also increases the resilience of the smart grid system

An Investigation of Cognitive Implications in the Design of Computer Games

Computer games have been touted for their ability to engage players in cognitive activities (e.g., decision making, learning, planning, problem solving). By ‘computer game’ we mean any game that uses computational technology as its platform, regardless of the actual hardware or software; games on personal computers, tablets, game consoles, cellphones, or specialized equipment can all be called computer games. However, there remains much uncertainty regarding how to design computer games so that they support, facilitate, and promote the reflective, effortful, and conscious performance of cognitive activities. The goal of this dissertation is to relieve some of this uncertainty, so that the design of such computer games can become more systematic and less ad hoc. By understanding how different components of a computer game influence the resulting cognitive system, we can more consciously and systematically design computer games for the desired cognitive support. This dissertation synthesizes concepts from cognitive science, information science, learning science, human-computer interaction, and game design to create a conceptual design framework. The framework particularly focuses on the design of: gameplay, the player-game joint cognitive system, the interaction that mediates gameplay and the cognitive system, and the components of this interaction. Furthermore, this dissertation also includes a process by which researchers can explore the relationship between components of a computer game and the resulting cognitive system in a consistent, controlled, and precise manner. Using this process, three separate studies were conducted to provide empirical support for different aspects of the framework; these studies investigated how the design of rules, visual interface, and the core mechanic influence the resulting cognitive system. Overall then, the conceptual framework and three empirical studies presented in this dissertation provide designers with a greater understanding of how to systematically design computer games to provide the desired support for any cognitive activity

Virtual Organization Clusters: Self-Provisioned Clouds on the Grid

Virtual Organization Clusters (VOCs) provide a novel architecture for overlaying dedicated cluster systems on existing grid infrastructures. VOCs provide customized, homogeneous execution environments on a per-Virtual Organization basis, without the cost of physical cluster construction or the overhead of per-job containers. Administrative access and overlay network capabilities are granted to Virtual Organizations (VOs) that choose to implement VOC technology, while the system remains completely transparent to end users and non-participating VOs. Unlike alternative systems that require explicit leases, VOCs are autonomically self-provisioned according to configurable usage policies. As a grid computing architecture, VOCs are designed to be technology agnostic and are implementable by any combination of software and services that follows the Virtual Organization Cluster Model. As demonstrated through simulation testing and evaluation of an implemented prototype, VOCs are a viable mechanism for increasing end-user job compatibility on grid sites. On existing production grids, where jobs are frequently submitted to a small subset of sites and thus experience high queuing delays relative to average job length, the grid-wide addition of VOCs does not adversely affect mean job sojourn time. By load-balancing jobs among grid sites, VOCs can reduce the total amount of queuing on a grid to a level sufficient to counteract the performance overhead introduced by virtualization

Task Allokation für effiziente Edge Computing Systeme

Im Bereich von Edge Computing nimmt die Rechenleistung in direkter Nähe zu den Sensoren stetig zu. Infolgedessen gibt es immer mehr rechen- und datenintensive Anwendungen, die im Edge Bereich ausgeführt werden können. Gleichzeitig befinden sie sich in einer sich ständig verändernden Systemumgebung. Um Ausfallzeiten und lange Redesign-Schleifen zu reduzieren, werden Selbstanpassungsfähigkeiten benötigt. Die automatische Reallokation der ausgeführten Aufgaben auf die Rechenknoten ist eine mögliche Selbstanpassungsmaßnahme. Die Reallokation sollte jedoch mit den verschiedenen Anforderungen, Einschränkungen und Spezifikationen des Entwurfs konform sein. Dabei besteht eine große Herausforderung darin, dass die Allokationsentscheidung schnell genug für die Berechnung zur Laufzeit sein sollte. Der Fokus dieser Arbeit ist die Realisierung einer effizienten Allokation, die Bedürfnisse in Form von Policies nutzt, um eine automatische Reallokation zur Laufzeit zu berechnen. In dieser Arbeit wurde eine effiziente Allokationsmethode entwickelt, die eine kombinierte Betrachtung von Ressourcenverfügbarkeit, Anwendungsbedarf und problemspezifischer Effizienzdefinition realisiert. Der Ansatz verfolgt eine modulare Beschreibung dieser Aspekte für die Allokation in Form von komponentenspezifischen Policies. Ein besonderer Schwerpunkt liegt auf der Allokation aufgrund von Veränderungen im laufenden Betrieb. Hierfür wird das Zuordnungsproblem zur Entwicklungszeit modelliert und die Informationen im Betrieb genutzt. Mit diesem Konzept konnten zwei industrielle Anwendungen modelliert und unterschiedliche Zuordnungen berechnet werden. Die Skalierbarkeit des Konzepts wurde durch Messungen validiert. Die Reallokation zur Laufzeit wurde mit einem Container Framework implementiert. Darauf aufbauend wurde der Overhead der Allokationsberechnung zur Laufzeit gemessen und in den Kontext der Reallokationszeit gesetzt. Die Berechnung einer effizienten Allokation trägt zur Autonomie von Recheninfrastrukturen bei. Dadurch erhöhen sich die Fähigkeiten zur Selbstadaption und die Resilienz dieser Rechennetze. Das spielt nicht nur im industriellen Edge-Cloud Kontext eine Rolle, sondern auch im Automobil, wenn zur Laufzeit über dynamische Betriebsstrategien entschieden werden soll

Cybersecurity of Digital Service Chains

This open access book presents the main scientific results from the H2020 GUARD project. The GUARD project aims at filling the current technological gap between software management paradigms and cybersecurity models, the latter still lacking orchestration and agility to effectively address the dynamicity of the former. This book provides a comprehensive review of the main concepts, architectures, algorithms, and non-technical aspects developed during three years of investigation; the description of the Smart Mobility use case developed at the end of the project gives a practical example of how the GUARD platform and related technologies can be deployed in practical scenarios. We expect the book to be interesting for the broad group of researchers, engineers, and professionals daily experiencing the inadequacy of outdated cybersecurity models for modern computing environments and cyber-physical systems