The majority of computers around us are embedded in productsand dedicated to perform certain tasks. A specific task is thecontrol of a dynamic system. The computers are ofteninterconnected by communication networks forming a distributedsystem. Vehicles and manufacturing equipment are two types ofmechatronic machines which often host dedicated computercontrol systems. A research problem is how the real-timebehaviour of the computer system affects the application,especially the control of the dynamic system. If the internal or external conditions varies over time, itbecomes difficult to assign a fixed resource reservation thatwill work well in all situations. In general, the more time anapplication gets of a resource, the better its gauged orperceived quality will be. A strategy is to alter the resourcereservation when the condition changes. This can be constructedas a negotiation between competing applications, a method forwhich the termquality of control, QoC, has been coined. Scalability isthe ability to change the structure and configuration of asystem. It promotes evolving systems and a can help manage acomplex product family. An architecture for a QoC middleware ontop of a scalable computer system, has been proposed. As aquality measureof a control application, the well-knownweighted quadratic loss function used in optimal control, hasbeen revised to encompass a subset of the so called timingproperties. The timing properties are the periods and thedelays in the control loop, including time-varying period anddelay. They are the interface between control and computerengineering, from a control engineering viewpoint. The qualitymeasure can be used both offline and on-line given a model ofthe sampled-data system and an appropriate description of thetiming properties. In order to use a computer system efficiently and toguarantee its responsiveness, real-time scheduling is a must.In fixed priority scheduling each task arrives periodically andhas a fixed priority. A task with a high priority can preempt alow priority task and gain access to the resource. Thebest-case response time characterizes the delays in the system,which is useful from a control viewpoint. A new algorithm tocalculate thebest-caseresponsetime has been derived. It is based on ascheduling scenario which yields a recurrence equation. Themodel is dual to the well-known worst-case response timeanalysis. Besides the dynamic fixed priority scheduling algorithm,optimal control usingstatic schedulinghas been studied, assuming a limitedcommunication. In the static schedule, which is constructedpre-runtime, each task is assigned a time window within aschedule repeated in eternity. The optimal scheduling sequenceis sought by optimizing the overall control performance. Aninteresting aspect is that the non-specified control periodfalls out as a result of theoptimal schedule. The time-varying delay is accountedfor in the control design. Keywords:Real-time scheduling, sampled-data control,performance measure, quality of control, limited communication,time-varying delay, jitter.

<p>The majority of computers around us are embedded in productsand dedicated to perform certain tasks. A specific task is thecontrol of a dynamic system. The computers are ofteninterconnected by communication networks forming a distributedsystem. Vehicles and manufacturing equipment are two types ofmechatronic machines which often host dedicated computercontrol systems. A research problem is how the real-timebehaviour of the computer system affects the application,especially the control of the dynamic system.</p><p>If the internal or external conditions varies over time, itbecomes difficult to assign a fixed resource reservation thatwill work well in all situations. In general, the more time anapplication gets of a resource, the better its gauged orperceived quality will be. A strategy is to alter the resourcereservation when the condition changes. This can be constructedas a negotiation between competing applications, a method forwhich the term<i>quality of control</i>, QoC, has been coined. Scalability isthe ability to change the structure and configuration of asystem. It promotes evolving systems and a can help manage acomplex product family. An architecture for a QoC middleware ontop of a scalable computer system, has been proposed.</p><p>As a<i>quality measure</i>of a control application, the well-knownweighted quadratic loss function used in optimal control, hasbeen revised to encompass a subset of the so called timingproperties. The timing properties are the periods and thedelays in the control loop, including time-varying period anddelay. They are the interface between control and computerengineering, from a control engineering viewpoint. The qualitymeasure can be used both offline and on-line given a model ofthe sampled-data system and an appropriate description of thetiming properties.</p><p>In order to use a computer system efficiently and toguarantee its responsiveness, real-time scheduling is a must.In fixed priority scheduling each task arrives periodically andhas a fixed priority. A task with a high priority can preempt alow priority task and gain access to the resource. Thebest-case response time characterizes the delays in the system,which is useful from a control viewpoint. A new algorithm tocalculate the<i>best-caseresponse</i>time has been derived. It is based on ascheduling scenario which yields a recurrence equation. Themodel is dual to the well-known worst-case response timeanalysis.</p><p>Besides the dynamic fixed priority scheduling algorithm,optimal control using<i>static scheduling</i>has been studied, assuming a limitedcommunication. In the static schedule, which is constructedpre-runtime, each task is assigned a time window within aschedule repeated in eternity. The optimal scheduling sequenceis sought by optimizing the overall control performance. Aninteresting aspect is that the non-specified control periodfalls out as a result of the<i>optimal schedule</i>. The time-varying delay is accountedfor in the control design.</p><p><b>Keywords:</b>Real-time scheduling, sampled-data control,performance measure, quality of control, limited communication,time-varying delay, jitter.</p>

Cyber-physical systems (CPS) are systems that are composed of physical and computational components. CPS components are typically interconnected through a communication network that allows components to interact and take automated actions that are beneficial for the overall CPS. Future Power-Grid is one of the major example of Cyber-physical systems. Traditionally, Power-Grids use a centralized approach to manage the energy produced at power sources or large power plants. Due to the advancement and availability of renewable energy sources such as wind farms and solar systems, there are more number of energy sources connecting to the power grid. Managing these large number of energy sources using a centralized technique is not practical and is computationally very expensive. Therefore, a decentralized way of monitoring and scheduling of energy across the power grid is preferred. In a decentralized approach, computational load is distributed among the grid entities that are interconnected through a readily available communication network like internet. The communication network allows the grid entities to coordinate and exchange their power state information with each other and take automated actions that lead to efficient consumption of energy as well as the network bandwidth. Thus, the future power grid is appropriately called a "Smart-Grid". While Smart-Grids provide efficient energy operations, they also impose several challenges in the design, verification and monitoring phases. The computer network serves as a backbone for scheduling messages between the Smart-Grid entities. Therefore, network delays experienced by messages play a vital role in grid stability and overall system performance. In this work, we study the effects of network delays on Smart-Grid performance and propose adaptive algorithms to efficiently schedule messages between the grid entities. Algorithms proposed in this work also ensure the grid stability and perform network congestion control. Through this work, we derive useful conclusions regarding the Smart-Grid performance and find new challenges that can serve as future research directions in this domain.

In real-word manufacturing environments, finding the right job sequences and their associated schedules when resource, precedence, and timing constraints are imposed is a difficult task. For most practical problems classical scheduling easily leads to an exponential growth in the number of possible schedules. Moreover, a decision time period of hours or even minutes is too long. Good solutions are often needed in real-time. The problem becomes even more complicated if changes, such as new orders or resource breakdowns, occur within the manufacturing system. One approach to overcome the challenges of solving classical scheduling problems is the use of distributed schemes such as agent or holonic-based control architectures. This dissertation presents an innovative control architecture that uses the holonic concept, capable of delivering good solutions when applied in dynamic environments. The general holonic control framework presented in this research has specific characteristics not found in others reported so far. Using a modular approach it takes into account all the categories of hardware and software resources of a manufacturing system. Due to its modularity, the holonic control framework can be used for assigning and scheduling different task types, separately or simultaneously. Thus, it can be used not only for assigning and scheduling transport tasks, but also for finding feasible solutions to the job assignment and scheduling of processing tasks, or to better utilize the auxiliary equipment and devices in a manufacturing system. In the holonic system, under real-time constraints, a feasible schedule for the material handling resources emerges from the combination of individual holon's schedules. Internal evaluation algorithms and coordination mechanisms between the entities in the architecture form the basis for the resultant schedules. The experimental results obtained show a percentage difference between the makespan values obtained using the holonic scheduling approach and the optimal values of under seven percent. Since current control systems in use in industry lack the ability to adapt to dynamic manufacturing environments, the holonic architecture designed and the tests performed in this research could be a part in the effort to build the foundations for the control systems of the next generation manufacturing systems. / Ph. D.

The present work studies methods of scheduling in heterogeneous distributed systems. First there are introduced some theoretical basics which contain not only the scheduling theory itself but also the graph theory and the computational complexity theory. After that, compile-time scheduling methods and some well-known algorithms solving the problem are presented, followed by real-time scheduling basics and by classification of used methods. In the main part of the work there are proposed algorithms which respect additional restrictions. These algorithms are tested via the enclosed application and compared either to each other or to another algorithms which mostly don't respect additional restrictions. The mentioned application and the documentation for this application are a part of this work as well.

FlexRay is a new automotive network communication protocol for control and interconnection among ECUs (electronic control units) in the cluster. In the FlexRay protocol, a communication cycle consists of static segment and dynamic segment. The static segment is a TDMA scheme designed for transmitting time-triggered messages. Due to its determinism and reliability, it is particularly applicable to X-by-wire applications. Each static slot is allocated to a specified task and the task can transmit message during the exclusive slot. However, if the task has no message to transmit during its assigned slot, the slot cannot be used by other tasks. The overall utilization is low if the bandwidth requirement of each task is not high. To improve the system utilization, we apply the real-time scheduling techniques to devising a deterministic, static cyclic scheduling. The objective is to reduce the demand on the number of static slots needed for scheduling time-triggered tasks. Specifically, we treat the set of static slots that are in the same position in every communication cycle as an individual real-time channel. We model each task as a real-time task, specified by (Ci,Ti). It requires that for every Ti communication cycles, the system must allocate at least Ci time slots to satisfy the real-time constraint of the task. We decompose each such task into a set of subtasks, allocate them to the real-time channels and then apply the rate-monotonic scheduling algorithm to schedule the subtasks within each channel. Finally, we perform computer simulation to evaluate the effectiveness of our proposal. From the simulation results, we conclude that our proposal is able to effectively reduce the demand for the static slots under a wide range of real-time requirements.

La conception des plateformes aéronautiques s’effectue en tenant compte des aspects fonctionnels et dysfonctionnels prévus dans les scénarios d’emploi des aéronefs qui les embarquent. Ces plateformes aéronautiques sont composées de systèmes informatiques temps réel qui doivent à la fois être précises dans leurs calculs, exactes dans l’instant de délivrance des résultats des calculs, et robustes à tout évènement pouvant compromettre le bon fonctionnement de la plateforme.Dans ce contexte, ces travaux de thèse abordent les ordonnancements temps réel tolérants aux fautes. Partant du fait que les systèmes informatiques embarqués sont perturbés par les ondes électromagnétiques des radars, notamment dans la phase d’approche des aéronefs, ces travaux proposent une modélisation des effets des ondes, dite en rafales de fautes. Après avoir exploré le comportement de l’ordonnanceur à la détection d’erreurs au sein d’une tâche, une technique de validation, reposant sur le calcul de pire temps de réponse des tâches, est présentée. Il devient alors possible d’effectuer des analyses d’ordonnançabilité sous l’hypothèse de la présence de rafales de fautes. Ainsi, cette technique de validation permet de conclure sur la faisabilité d’un ensemble de tâches en tenant compte de la durée de la rafale de fautes et de la stratégie de gestion des erreurs détectées dans les tâches.Sur la base de ces résultats, les travaux décrits montre comment envisager l’analyse au niveau système. L’idée sous-jacente est de mettre en évidence le rôle des ordonnancements temps réel tolérants aux fautes dans la gestion des données erronées causées par des perturbations extérieures au système.Ainsi, le comportement de chaque équipement est modélisé, ainsi que les flots de données échangés et la dynamique du système. Le comportement de chaque équipement est fonction de la perturbation subie, et donne lieu à l’établissement de la perturbation résultante, véritable réponse dysfonctionnelle de l’équipement à une agression extérieure. / The design of avionic platforms takes into account the functional and dysfunctional aspects, which depend on the aircraft operation concept. These avionic platforms embed computer resources that must produce accurate results at the right time, and must be dependable whatever the disturbance.In this specific context, we address the topic of fault tolerant real time scheduling. Since the embedded computer resources are disturbed by electromagnetic waves produced by radar, especially during the aircraft approach, we suggest a model of these wave effects named fault bursts. Afterthe analysis of scheduler behaviour when an error is dectected inside a task, we present a validation technique based on the evaluation of the worst case response time. By this way, we are able to study the task set feasibility under fault burst assumption and according to the error recovery strategy.Then, based on these results, we show a way to analyse the effects of disturbances such as electromagnetic waves at system level. The underlining idea is to demonstrate the main role of fault tolerant real time scheduler in the management of erroneous data. To do that, we suggest an equipment model which integrates the behaviour of the equipement when a disturbance occurs. We also describe thedata flows in order to describe the avionics platform dynamics.

Orientador: Rubens Maciel Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-19T04:22:50Z (GMT). No. of bitstreams: 1 Goncalves_EncarnacaodeLourdesBassoliAndreo_D.pdf: 4732830 bytes, checksum: 01a1b5e8274e002cb44c8ed8cd836b0a (MD5) Previous issue date: 2011 / Resumo: As usinas de produção de Etanol estão apresentando necessidades relacionadas ao aumento de produtividade com redução de custos. O processo de produção de etanol necessita de ações que resolvam problemas da automação, tais como variabilidade das malhas de controle, longo tempo de operação de sistema de controle em modo manual. Apresentam problemas de sinergia entre as áreas do processo produtivo, demora na tomada de decisão e dificuldade para definir a ação a ser tomada para solução do problema. Motivados por estes fatores e com a tecnologia de informação e da automação disponível atualmente no mercado, desenvolveu-se um modelo de processo, baseado em variáveis, com origem em diversas fontes (área agrícola, automação, administrativa, industrial), efetuando integrações destas variáveis em uma única base de dados, produção de regras de negócio com alarmes e instruções para tomada de decisões de correção ou mudança do processo produtivo. Este modelo usa os softwares ERP (Enterprise Resource Planning), transacionais, MES (Manufacturing Execution Systems) e automação industrial. Este trabalho apresenta uma revisão bibliográfica com as principais definições necessárias para o desenvolvimento e entendimento do modelo, tais como descrição dos softwares, descrição do processo de automação e descrição do processo produtivo de etanol. Apresenta o modelo proposto e um estudo de caso, onde o modelo foi aplicado em uma unidade produtora de etanol / Abstract: The ethanol production plants are experiencing needs related to increasing productivity while reducing costs. The ethanol production process requires actions that address problems of automation, such as variability of the control loops, long time of operation control system in manual mode. This process has problems of synergy between the areas of the production, delay in decision making and difficulty in defining the action to be taken to solve the problems. Motivated by these factors and the information technology and automation available today, a process model has been developed based on variables, originating from various sources (agricultural area, automation, administrative, industrial), performing integrations of these variables in a single database, production of business rules with alarms and instructions for making decisions to correct or change the production process. This model, use the software ERP (Enterprise Resource Planning), transactional, MES (Manufacturing Execution Systems) and industrial automation. This paper presents a literature review with the main definitions needed for the development and understanding of the model, such as descriptions of the software, description of the automation process and description of the ethanol production process. Presents the proposed model and a case study, where the model was applied in an ethanol production unit / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química

As an increasing position of the world’s communication moves towards the cloud and wireless solutions the requirement for good throughput and low delay increases. One step towards meeting higher requirements is the move from 4G Long Term Evolution (LTE) to 5G New Radio (NR). In order to utilize the potential of 5G NR, software needs to be improved. With the goal to lower the delay for delay critical applications and services when using 5G NR this thesis studies a new scheduler inspired by Earliest Deadline First (EDF) as a soft real-time system scheduler. This new scheduler called Real-Time Inspired Hybrid Scheduler (RTIHS) is proposed where two different schedulers are used depending on if the network traffic is delay critical or not. Delay critical traffic is served by the new Deadline Inspired Scheduler (DIS) scheduler and other traffic by a traditional Round Robin (RR) scheduler. The transmissions that are delay critical are prioritized differently with the use of a constant that has two functions. To determine if the transmission is in time or not, and how close the transmission is to the fixed deadline. Up until the deadline the priority of that transmission is increased with a factor that is affected by how close the current time is to the deadline. If the deadline has been missed the priority is, however, decreased with respect to how much it missed the deadline.RTIHS is implemented and tested in a state-of-the-art system simulator where services such as;Cloud Gaming (CG), Video on Demand (VoD), and web browsing are evaluated. An already existing technology named Low Latency Low Loss Scalable Throughput (L4S) is included in the evaluations to investigate how RTIHS scales. The performance of RTIHS is then compared to a Delay Scheduler(DS) and a RR scheduler that act as the baseline. The results show that RTIHS performs better for CG in terms of delay and nominal rate than the baseline, especially when the network is under high load. Using RTIHS compared to a DS shows an average increase of nominal rate by roughly 6 % and an average decrease of delay by 16 % for the average users. At the same time RTIHS does show higher delay and lower throughput for services such as VoD and web browsing, making its performance for those service worse than the baseline, especially when the network load is high. With the same comparison as before, RTIHS shows an average 17 % higher delay for web browsing and 1 % lower requested video rate than the DS for the average users. This is due to how the evaluated services are prioritized with the limited resources available. Since RTIHS prioritizes CG more, less resources remain for the other services. The baseline is not as biased towards CG and therefore has a lower nominal rate and higher delay for said service but better for the other services in comparison. Activating L4S mitigates the underwhelming performance of RTIHS for VoD and web browsing further improves the performance for CG. This is also true for the baseline which increases performance for CG and further increases the performance for other services with a small amount. With L4S activated the average increase of nominal rate in CG for RTIHS compared to the DS is 13 % for the average users and the average delay decrease is 9 %. Meanwhile the average requested video rate for RTIHS is less than 1 % lower than that of the DS for the average users and the delay for web browsing is 10 % higher than the DS for the average users.

With the advancement in technology, modern autonomous vehicles are required to perform more complex tasks and navigate through challenging terrains. Thus, the amount of computation resources to accurately accomplish those tasks have exponentially grown in the last decade. With growing computational intensity and limited computational resources on embedded devices, schedulers are necessary to manage and fully optimize computational loads between the GPU and CPU as well as reducing the power consumption to maximize time in the field. Thus far, it has been proven the effectiveness of schedulers and path planners on computational load on embedded devices through numerous bench testing and simulated environments. However, there have not been any significant data collection in the real-world with all hardware and software combined. This thesis focuses on the implementation of various computational loads (i.e. scheduler, path planner, RGB-D camera, object detection, depth estimation, etc.) on the NVIDIA Jetson AGX Xavier and real-world experimentation on the Clearpath Robotics Jackal. We compare the computation response time and effectiveness of all systems tested in the real-world versus the same software and hardware architecture on the bench. / Master of Science / Modern autonomous vehicles are required to perform more complex tasks with limited computational resources, power and operating frequency. In recent past, the research around autonomous vehicles have been focused on proving the effectiveness of using software-based programming on embedded devices with integrated GPU to improve the overall performance by speeding up task completion. Our goal is to perform real-world data collection and experimentation with both hardware and software frameworks onboard the Clearpath Robotics Jackal. This will validate the efficiency and computational load of the software framework under multiple varying environments.