Cloud native computing for Industry 4.0: Challenges and opportunities

Proceedings of: 26th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA ), 7-10 Sept. 2021, Vasteras, Sweden.Cloud-based architectures are advantageous in aspects such as scalability, reliability and resource utilization efficiency, to name just a few, thus being considered one of the pillars of Industry 4.0. However, in this domain, cloud computing platforms are subject to specific requirements, namely in what concerns real-time performance, determinism and fault-tolerance. This paper focuses on cloud native computing, which is an emerging and promising cloud-computing paradigm, specifically addressing its applicability to real-time systems. Firstly, it introduces the architecture of cloud native applications, discussing their principles, potential advantages and challenges. Then it addresses the opportunities and constraints of such technologies when applied to industrial real-time systems.This work has been supported by EC H2020 5GPPP 5Growth project (Grant 856709)

Response Time Analysis for RT-MQTT Protocol Grounded on SDN

The current industry trend is to replace the use of custom components with standards-based Commercially available Off-The-Shelf (COTS) based hardware and protocols. Furthermore, the emergence of new industrial paradigms, such as Industry 4.0 and the Industrial Internet of Things, sets additional requirements regarding e.g. scale, transparency, agility, flexibility and efficiency. Therefore, in these domains, application layer protocols such as Message Queuing Telemetry Transport protocol (MQTT) are gaining popularity, in result of their simplicity, scalability, low resource-usage and decoupling between end nodes. However, such protocols were not designed for real-time applications, missing key features such as determinism and latency bounds. A recent work proposed extending MQTT with real-time services, taking advantage of Software Defined Networking (SDN) to manage the network resource. These extensions allow applications to specify real-time requirements that are then captured by a resource manager and used to reserve the necessary resources at the network layer. This paper shows that such MQTT extended architecture is analyzable from a worst-case timing perspective. We derive a system model that captures the real-time features and we present a response-time analysis to assess the schedulability of the real-time traffic. Finally, we validate the analysis with a set of experimental results

Recent Advances in Smart Farming

The Digital Transformation, which has the Internet of Things (IoT) as one of its pillars, is penetrating all aspects of our society with dramatic effects. In fact, buzzwords such as “Smart homes”, “Smart offices”, “Smart health” and “Smart factories”, to name just a few, have become a commonplace and reflect the profound structural changes that the Digital Transformation is having in the way citizens live their lives and how businesses and industries are organized.info:eu-repo/semantics/publishedVersio

A Real-Time Software Defined Networking Framework for Next-Generation Industrial Networks

Industry 4.0 brings in a whole set of new requirements to engineering industrial systems, with notorious impact at the networking layer. A key challenge posed by Industry 4.0 is the operational flexibility needed to support on-the-fly reconfiguration of production cells, stations, and machines. At the networking layer, this flexibility implies dynamic packet handling, scheduling, and dispatching. SoftwareDefined Networking (SDN) provides this level of flexibility in the general Local Area Network (LAN) domain. However, its application in the industry has been hindered by a lack of support for real-time services. This paper addresses this limitation, proposing an extended SDN OpenFlow framework that includes realtime services, leveraging existing real-time data plane Ethernet technologies. We show the OpenFlow enhancements, a real-time SDN controller, and experimental validation and performance assessment. Using a proof-of-concept prototype with 3 switches and cycles of 250µs, we could achieve 1µs jitter on timetriggered traffic and a reconfiguration time between operational modes below 10msinfo:eu-repo/semantics/publishedVersio

Exploring Alternatives to use Master/Slave Full Duplex Switched Ethernet for Avionics Embedded Applications

The complexity of distributed real-time systems, including military embedded applications, is increasing due to an increasing number of nodes, their functionality and higher amounts of exchanged data. This higher complexity imposes major development challenges when nonfunctional properties must be enforced. On the other hand, the current military communication networks are a generation old and are no longer effective in facing such increasingly complex requirements. A new communication network, based on Full Duplex Switched Ethernet and Master/slave approach, has been proposed previously. However, this initial approach is not efficient in terms of network bandwidth utilization. In this paper we propose two new alternative approaches that can use the network bandwidth more efficiently. In addition we provide a preliminary qualitative assessment of the three approaches concerning different factors such as performance, scalability, complexity and flexibility

Foreword to the Special Issue on Advanced IoT Technologies in Agriculture

In recent decades, the perception of the impact of humanity’s ecological footprint has changed dramatically; it is now widely recognized that natural resources are limited and sensitive, and that their indiscriminate use is unsustainable and deeply impacts the well-being of people, animals and plants [1,2,3]. The awareness that in order to reverse this problem, we must Reduce, Reuse, and Recycle, leads to the emergence of new and disruptive paradigms in most aspects of human activity, including agriculture [4,5]. In fact, agriculture has a tremendous impact on food supplies for the world, but also on the environment, and can compromise the ecological balance, thus, endangering sustainability [6]. The search for new methodologies applied to agricultural production addresses recent technologies, most of which arise from the Internet of Things (IoT), enabling a massive and unprecedented deployment of digital devices and services in a range of application domains that always increases [6,7,8]. This trend, commonly referred to as Smart Farm, Precision Livestock Farm or Farm 4.0, consists of the use of a wide range of sensors that monitor the evolution of the impacted conditions in agriculture, transmitting these data through communication systems, typically wirelessly. These data are then analyzed, often using Artificial Intelligence techniques, supporting management decisions with the goal to optimize agricultural production, including economical aspects such as productivity, quality and profitability, and sustainability [9,10]. The management of agricultural processes is based on accurate information, both on current conditions and on the forecast of future developments, and it allows for gains in the efficiency of agricultural processes, both in terms of economics and environmental impact [7]. Indeed, we intend with this Special Issue on Advanced IoT Technologies in Agriculture to present developments in research, focusing on the application of new methods to pinpoint or solve problems and constraints in agriculture and livestock production, based on IoT, making use of emerging technologies such as large data, sensor networks, image analysis, unmanned aerial vehicles (UAV), mobile applications, cloud computing, robots or artificial intelligence. Examples of the application of such technologies to irrigation, fertilization, seeding, soil management, pest and disease detection, animal feeding, breeding and welfare, impacting on farming productivity, profit and environment sustainability, are also welcome.info:eu-repo/semantics/publishedVersio

Suporte de comunicações tempo-real flexíveis em sistemas distribuidos

Doutoramento em Engenharia ElectrónicaDistributed computer-control systems (DCCS) are widely disseminated, appearing in applications ranging from automated process and manufacturing control to automotive, avionics and robotics. Many of these applications comprise real-time activities, that is, activities that must be performed within strict time bounds. Due to its distributed nature, these systems comprise multiple autonomous processing units that, despite being autonomous, need to exchange data in order to achieve control over the environment. For this reason the data exchange among different nodes is also subject to real-time constraints, and thus the communication subsystem must be able to deliver data within specific time bounds. Many DCCS applications are complex and heterogeneous, comprising different sets of activities with different properties and requirements. For instance, they commonly include periodic activities, e.g. resulting from closed loop control, and sporadic activities resulting from events that occur at unpredictable instants in time in the environment under control. These types of activities can have distinct levels of criticalness and timeliness requirements, independently of their activation nature. On the other hand, flexibility is becoming increasingly important in DCCS, due both to the need of reducing the costs of set-up, configuration changes and maintenance, and also to the recent use of DCCS in new types of applications, such as agile manufacturing, real-time databases with variable number of clients, automotive, mobile robotics in unstructured environments and automatic traffic control systems, that must deal with environments that are inherently dynamic. To cope with such high degree of complexity and dynamism, distributed real-time systems must support both time and event-triggered communication services under timing constraints and, at the same time, they must be operationally flexible, supporting on-the-flv changes to the computational activities they execute. Concerning specifically the communication subsystem, existing real-time protocols do not generally fulfill these requirements. In systems eminently time-triggered, event-triggered services are either non-existing or handled inefficiently, while in systems eminently event-triggered, interesting properties of time-triggered services are normally lost. On the other hand, flexibility and timeliness are often considered as conflicting: systems that provide timeliness guarantees are based on a static configuration of the communication activities while systems that support dynamic changes to the communication activities do not provide timeliness guarantees. The communication paradigm herein presented, the Flexible Time-Triggered communication (FTT) paradigm, centralizes the communication requirements and scheduling of synchronous traffic in a single node and uses a master/multi-slave schedule distribution technique that requires low overhead and is independent of the particular scheduling algorithm employed. This architecture facilitates the implementation of on-line scheduling, which supports dynamic changes to the message set properties, and the implementation of on-line admission control, which permits to ensure that changes to the message set are only accepted if the timeliness requirements are all met. In some application domains DCCS are also facing a trend towards higher flexibility in order to support on-line Qualitv-of-Service (QoS) management. This feature is generally useful to increase the efficiency in the utilization of system resources since typically there is a direct relationship between resource utilization and delivered QoS. On-line QoS management requires a high level of flexibility, and thus this dissertation also describes how the FTT communication paradigm can support such type of services. This dissertation presents the FTT paradigm and argues that this paradigm allows to combine in the same communication system different types of traffic, with the ability to change their properties and the respective scheduling policy at run-time, without relinquishing predictability guarantees and achieving efficient use of network bandwidth. The FTT paradigm presented in this thesis has its roots in the FTT-CAN protocol. After some work performed over the FTT-CAN protocol, it was realized that the main concepts could be abstracted and used to build a generic communication paradigm, which could be implemented in distinct communication networks. To assess the performance of the FTT paradigm, this dissertation includes some contributions to the FTT-CAN protocol, mainly in what concerns scheduling and response-time analysis. Moreover, it also presents an implementation over Ethernet (FTT-Ethernet), which aims at more resource demanding applications, supporting for instance multimedia activities. For this reason, in the scope of the FTT-Ethernet protocol most of the work presented is related to on-line QoS management.Os sistemas distribuídos controlados por computador (Distributed Computer-Contrai Systems / DCCS) encontram-se largamente disseminados, cobrindo aplicações que vão desde automação e controlo de processos industriais à aviónica, robótica e controlo automóvel. Muitas destas aplicações incluem actividades com características de tempo-real, i.e., actividades que tem de ser executadas durante janelas temporais bem definidas. Pela sua natureza distribuída, estes sistemas compreendem múltiplas unidades de processamento as quais, apesar de autónomas, necessitam de comunicar entre si para assegurar o controlo global do sistema. Assim, a troca de dados entre nodos encontra-se também sujeita a restrições temporais, donde o sistema de comunicação tem de garantir que esta ocorre de acordo com as restrições temporais requeridas pela aplicação. Muitas aplicações de DCCS são complexas e heterogéneas, incluindo diferentes conjuntos de actividades, as quais exibem diferentes propriedades e requisitos. Por exemplo, encontram-se frequentemente actividades periódicas, resultando por exemplo de controladores operando cm malha fechada, c actividades esporádicas resultantes de eventos que ocorrem cm instantes imprevisíveis no ambiente a controlar. Todavia, a importância c tipos de requisitos temporais destas actividades são independentes da natureza da sua activação. Por outro lado, cm sistemas DCCS a flexibilidade tem vindo a crescer de importância, em resultado quer da necessidade de reduzir custos de instalação, configuração c manutenção, quer do uso deste tipo de sistemas cm aplicações emergentes, como manufactura ágil (flexible manufacturing), bases de dados de temporal com número variável de clientes, robótica móvel cm ambientes não estruturados c controlo automático de tráfego, que tem de lidar com ambientes que são inerentemente dinâmicos. Aplicações exibindo este grau de complexidade c dinamismo requerem sistemas suportando serviços activados quer pela passagem do tempo {time-triggered ) quer por eventos (event-triggered) com garantias temporais c ao mesmo tempo exibindo flexibilidade operacional, suportando alterações dinâmicas às características das actividades que compreendem. No que respeita especificamente ao sistema de comunicação, os protocolos existentes genericamente não preenchem estes requi¬sitos. Em sistemas eminentemente tiine.-trigge.red, os serviços eve.nt-trigge.red não existem ou são implementados de uma forma ineficiente, enquanto cm sistemas eminentemente eve.nt-trigge.red algumas das propriedades mais interessantes exibidas pelos sis¬temas time.-trigge.red são perdidas. Por outro lado flexibilidade c garantias temporais tem sido consideradas como propriedades conflituosas; sistemas que providenciam serviços com garantias temporais frequentemente requerem a especificação estática dos requisitos de comunicação, enquanto sistemas que suportam alte¬rações dinâmicas aos requisitos de comunicação usualmente não fornecem garantias temporais. O paradigma de comunicação apresentado nesta tese, denomi¬nado Flexible Time-Triggered communication (FTT), concentra os requisitos de comunicação e o escalonamento de tráfego num único nodo c utiliza uma técnica para distribuição do escalona¬mento denominada master/multi-slave. Esta caracteriza-se por consumir pouca largura de banda c por ser independente do al¬goritmo de escalonamento utilizado. Esta arquitectura facilita não só a implementação de escalonamento on-line., suportando portanto alterações aos requisitos de comunicação durante o fun¬cionamento do sistema, como também a implementação on-line. de controlo de admissão, o que permite rejeitar alterações que comprometam as garantias temporais do sistema, assegurando assim um comportamento previsível.Em alguns domínios específicos de aplicação de DCCS, verifica-se uma necessidade crescente de suporte a gestão on-line de Quali¬dade de Serviço (Quality of Service. / QoS). Genericamente, esta funcionalidade permite aumentar a eficiência da exploração dos recursos do sistema, pois habitualmente verifica-se uma relação directa entre o grau de recursos alceados às actividades de um sistema c o respectivo QoS. A gestão dinâmica de QoS requer um alto grau de flexibilidade, donde esta tese também descreve como o paradigma FTT suporta este tipo de serviço no que concerne ao tráfego.Esta tese apresenta o paradigma FTT c defende que este permite combinar no mesmo sistema de comunicação diferentes tipos de tráfego, com a possibilidade de alterar as suas propriedades, exe¬cutar gestão de QoS c alterar a politica de escalonamento durante o funcionamento, sem comprometer as garantias temporais gran¬jeadas ao tráfego c atingindo uma elevada eficiência no uso da largura de banda.O paradigma FTT apresentado nesta tese teve a sua génese no protocolo FTT-CAN. Após algum trabalho realizado sobre este protocolo verificou-se que os conceitos principais poderiam ser abstraídos, resultando um paradigma de comunicação genérico, passível de implementação em diversos meios de comunicação. Para verificar a performance do paradigma FTT, esta dissertação inclui algumas contribuições relativas ao protocolo FTT-CAN, nomeadamente no que concerne ao estudo do desempenho cm termos de escalonamento c análise de tempos de resposta. Por outro lado é também apresentada a implementação do paradigma FTT sobre Ethernet (FTT-Ethernet), a qual se destina a aplica¬ções mais exigentes no que respeita a poder de processamento c largura de banda, por exemplo aplicações integrando tráfego multimédia. No que respeita a este último protocolo explora-se essencialmente assuntos como a gestão dinâmica de QoS

A real-time distributed software infrastructure for cooperating mobile autonomous robots

Cooperating mobile autonomous robots have been generating a growing interest in fields such as rescue, demining and security. These applications require a real time middleware and wireless communication protocol that can effecient and timely support the fusion of the distributed perception and the development of coordinated behaviors. This paper proposes an affordable middleware, based on low-cost and open-source COTS technologies, which relies on a real-time database partially replicated in all team members, containing both local and remote state variables, in a distributed shared memory style. This provides seamless access to the complete team state, with fast non-blocking local operations. The remote data is updated autonomously in the background by a WiFi-based wireless communication protocol, at an adequate refresh rate. The software infrastruture is complemented with a task manager that provides scheduling and synchronization services to the application processes on top of the Linux operating system. Such infrastructure has been successfully used for four years in one RoboCup middle-size soccer team, and it has proved to be dependable in the presence of uncontrolled spurious traffic in the communication channel, using an adaptive technique to synchronizating the robots in the team and reconfiguring the communications dynamically and automatically according, to the number of currently active team members

Towards Efficient Transient Fault Handling in Time-Triggered Systems

DETITransient communication faults in distributed control systems (DCS) are unavoidable but must be handled adequately in order to enforce correct system behaviour. A typical way of handling transient faults is temporal redundancy by means of retransmissions. However, DCS are frequently designed with time-triggered architectures, being scheduled offline and not coping efficiently with retransmissions as these require the pre-allocation of bandwidth that, in the absence of errors, is wasted. In this paper we propose using the Flexible Time-Triggered paradigm to reconcile the Time-Triggered model with on-line scheduling of retransmissions when needed, only, leading to an efficient bandwidth usage. This is confirmed with preliminary experimental results obtained on an FTT-CAN network