Assessment of Response Time for New Multi Level Feedback Queue Scheduler

Response time is one of the characteristics of scheduler, happens to be a prominent attribute of any CPU scheduling algorithm. The proposed New Multi Level Feedback Queue [NMLFQ] Scheduler is compared with dynamic, real time, Dependent Activity Scheduling Algorithm (DASA) and Lockes Best Effort Scheduling Algorithm (LBESA). We abbreviated beneficial result of NMLFQ scheduler in comparison with dynamic best effort schedulers with respect to response time.Comment: 7 pages, 5 figure

Performance analysis of real-time and general-purpose operating systems for path planning of the multi-robot systems

In general, modern operating systems can be divided into two essential parts, real-time operating systems (RTOS) and general-purpose operating systems (GPOS). The main difference between GPOS and RTOS is the system istime-critical or not. It means that; in GPOS, a high-priority thread cannot preempt a kernel call. But, in RTOS, a low-priority task is preempted by a high-priority task if necessary, even if it’s executing a kernel call. Most Linux distributions can be used as both GPOS and RTOS with kernel modifications. In this study, two Linux distributions, Ubuntu and Pardus, were analyzed and their performances were compared both as GPOS and RTOS for path planning of the multi-robot systems. Robot groups with different numbers of members were used to perform the path tracking tasks using both Ubuntu and Pardus as GPOS and RTOS. In this way, both the performance of two different Linux distributions in robotic applications were observed and compared in two forms, GPOS, and RTOS

Epistemic Orientation for the Technological Future. Toward a Research Agenda for Dealing with Social Challenges of Internet of Things

This paper offers an epistemological and theoretical framework, and a research agenda, to face the main ethical and social pitfalls of the deployment of big data and IoT in social domains (SIoT). We rely on the concept of critical optimism to explain epistemic orientation about the technological future, paying particular attention to the social challenges. The framework drives the creation of an agenda for social researchers that aids to detect more evidence on the SIoT opportunities

Requisitos para adoção de sistemas operacionais embarcados

Embedded systems are part of numerous applications, most of which include real-time or specialized operating systems. The operating system must be chosen taking into account functional and technical characteristics of the embedded product. This paper presents a survey on the main requirements to help determine whether an operating system should be used in an embedded design, further we show how these requirements may be used for assessing the operating system selection.Os sistemas embarcados compõem a grande maioria dos dispositivos eletrônicos. A decisão de usar um sistema operacional é umas das mais importantes em um projeto embarcado. Para auxiliar nestas decisões, este artigo apresenta os principais requisitos que podem ser considerados em um projeto embarcado. Em seguida apresentamos os critérios para decisão sobre o uso ou não de um sistema operacional e os requisitos técnicos e comerciais utilizados na escolha de um sistema operacional embarcado

Real-Time Systems: An Introduction and the State-of-the-Art

This encyclopedia article gives an overview of the broad area of real-time systems. This task is daunting because real-time systems are everywhere, and yet no generally accepted definition differentiates real-time systems from non-real-time systems

Features real-time operating system for LabVIEW

Práce pojednává o vybraných vlastnostech operačních systémů reálného času (RTOS) Ardence PharLap ETS, WindRiver VxWorks a LabVIEW RT modulu.V práci jsou navrženy tři metodiky porovnávání kvality RTOS, z toho dvě jsou prakticky ověřovány popsanými experimenty na hardwaru CompactRIO od NI. V dalších částech práce je rozebrána potřeba použití RTOS a experimentální porovnání vlivu jitter chyby na činitele harmonického zkreslení THD vyjádřeného dvěma definicemi.This thesis deals with certain properties of real time operating systems (RTOS) Ardence PharLap ETS, WindRiver VxWorks and LabVIEW RT module. Three methodologies of RTOS quality comparison are proposed, two of which are practically tested with described experiments on CompactRIO hardware from NI. Furthermore, there is explained need for RTOS usage and experimental comparison of jitter error influence on total harmonic distortion THD defined by two definitions.

Investigation on the mobile robot navigation in an unknown environment

Mobile robots could be used to search, find, and relocate objects in many types of manufacturing operations and environments. In this scenario, the target objects might reside with equal probability at any location in the environment and, therefore, the robot must navigate and search the whole area autonomously, and be equipped with specific sensors to detect objects. Novel challenges exist in developing a control system, which helps a mobile robot achieve such tasks, including constructing enhanced systems for navigation, and vision-based object recognition. The latter is important for undertaking the exploration task that requires an optimal object recognition technique. In this thesis, these challenges, for an indoor environment, were divided into three sub-problems. In the first, the navigation task involved discovering an appropriate exploration path for the entire environment, with minimal sensing requirements. The Bug algorithm strategies were adapted for modelling the environment and implementing the exploration path. The second was a visual-search process, which consisted of employing appropriate image-processing techniques, and choosing a suitable viewpoint field for the camera. This study placed more emphasis on colour segmentation, template matching and Speeded-Up Robust Features (SURF) for object detection. The third problem was the relocating process, which involved using a robot’s gripper to grasp the detected, desired object and then move it to the assigned, final location. This also included approaching both the target and the delivery site, using a visual tracking technique. All codes were developed using C++ and C programming, and some libraries that included OpenCV and OpenSURF were utilized for image processing. Each control system function was tested both separately, and then in combination as a whole control program. The system performance was evaluated using two types of mobile robots: legged and wheeled. In this study, it was necessary to develop a wheeled search robot with a high performance processor. The experimental results demonstrated that the methodology used for the search robots was highly efficient provided the processor was adequate. It was concluded that it is possible to implement a navigation system within a minimum number of sensors if they are located and used effectively on the robot’s body. The main challenge within a visual-search process is that the environmental conditions are difficult to control, because the search robot executes its tasks in dynamic environments. The additional challenges of scaling these small robots up to useful industrial capabilities were also explored

Προσομοιωτές χρονοπρογραμματισμού πραγματικού χρόνου, Λειτουργικά συστήματα πραγματικού χρόνου.

Στην εργασία αυτή αφού γίνει μία σύντομη περιγραφή των συστημάτων πραγματικού χρόνου μελετώνται οι αλγόριθμοι χρονοπρογραμματισμού για συστήματα πραγματικού χρόνου. Γίνεται η περιγραφή προσομοιωτών χρονοπρογραμματισμού που έχουν στόχο την έρευνα και την εκπαίδευση και παρέχονται δωρεάν. Από αυτούς περιγράφετε εκτενώς η χρήση του προσομοιωτή Cheddar. Τέλος περιγράφονται τα λειτουργικά συστήματα πραγματικού χρόνου και γίνεται αναλυτική περιγραφή των προτύπων και κάποιων υλοποιήσεων τόσο από το χώρο του ελεύθερου λογισμικού όσο και από τον χώρο του εμπορικού λογισμικούIn this paper after a brief description of the real-time systems we study scheduling algorithms for real-time systems. We study a number of scheduling simulators aimed at research and education area and are free of any charge. We study in depth the Cheddar simulator. Finally we describe the real time operating systems and give detailed descrip-tion of standards and some implementations from the open software community and from the commercial software

Diseño e implementación de un módulo para la realización de prácticas en la asignatura “Sistemas de Tiempo Real” basado en el sistema operativo RTEMS

El fin del presente proyecto es la creación de un entorno de trabajo que englobe las herramientas necesarias para el desarrollo de aplicaciones de tiempo real y que permita después, generar una aplicación concreta que forme una de las prácticas de la asignatura “Sistemas de Tiempo Real” correspondiente al Grado en Ingeniería Informática de la Universidad Carlos III de Madrid. En concreto, en este proyecto se utilizará el sistema operativo de tiempo real RTEMS para la implementación de un módulo correspondiente a un servidor de control remoto y la plataforma Arduino para el desarrollo del módulo correspondiente a un sistema de control empotrado en un dispositivo concreto. Ambos módulos se comunicarán entre sí para lograr un objetivo final y conformarán la práctica que los futuros alumnos deben realizar. Además se proporciona la documentación necesaria para la creación del entorno de trabajo así como se propone el enunciado y los criterios de evaluación para una posible práctica.Ingeniería Informátic

Contributions to the safe execution of dynamic component-based real-time systems

Traditionally, real-time systems have based their design and execution on barely dynamic models to ensure, since design time, the temporal guarantees in the execution of their functionality. Great effort is being applied nowadays to progressively develop more dynamic systems, with the target of changing during their execution and to adapt themselves to their environment. The capability to change and to reconfigure themselves represents remarkable advantages as the capability to fix errors and to add new functionality with on-line updates. This means to be able to be updated without needing to stop the service, that may imply monetary losses in many cases. Design and development techniques based on components have become popular due to the use of components, which allows simplifying the system design, code reusability and updates through the substitution of components. The target of this thesis work is to provide certain degree of dynamism to real-time systems allowing them to replace components, incorporating new functionality of fixing existing bugs. On that purpose, a component-based framework is proposed, as well as the corresponding task in charge of providing dynamism to the system. The main contribution is to provide a framework to allow safe component replacements. Safe meaning that incorrect executions of tasks are avoided even y multiple tasks are executing concurrently and making use of the same data. Also that temporal guarantees are provided for every task. This framework incorporates a generic component model with real-time threads, a components replacement model with execution times that are known and bounded, and different strategies to apply such component replacement model. Some mechanisms to maintain a seamless and safe execution, regarding concurrency, before, during, and after applying the processes in charge of replacing running components are also described. Seamless execution means that components themselves do not perform the replacements, and safe means that temporal guarantees are provided and components are not affected in their execution. Part of these mechanisms are the system schedulability analysis and the framework tasks as well as reserving the needed resources for such scheduling to be correct. ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Los sistemas de tiempo real han basado tradicionalmente su desarrollo en modelos altamente predecibles ya que estos requieren garantías temporales en su ejecución. A lo largo de los años, la technología de tiempo real ha ido penetrando en diferentes campos de aplicación y ajustándose a paradigmas de desarrollo software más novedosos. Esto ha presentado y presenta en la actualidad un tremendo reto ya que estas aplicaciones suelen tener un alto grado de dinamismo, lo que entra en conflicto con la predictibilidad temporal y, en general la ejecución segura de los mismos. Hoy en dia se esta realizando un gran esfuerzo en el desarrollo de sistemas cada vez más dinamicos que permitan adaptar su estructura en tiempo de ejecución para adaptarse a entornos que presentan condiciones cambiantes. La capacidad de soportar este tipo de dinamismo presenta ventajas descatables como permitir corregir fallos y anadir funcionalidad mediante actualizaciones en caliente, es decir, poder actualizarse sin necesidad de realizar paradas en su servicio, lo que podria implicar costes monetarios en muchos casos o perdidas temporales de servicio. Por otro lado, las técnicas de diseño y desarrollo basadas en componentes se han hecho muy populares y su aplicación a los sistemas de tiempo real gana terreno día a día. Uno de los principales motivos de ellos es que el uso de componentes permite simplificar el diseño del sistema, la reutilizacion de codigo e incluso la actualizacion del mismo mediante la substitucion de componentes. En esta tesis se aborda el objetivo de proveer a los sistemas de tiempo real de cierto grado de dinamismo para poder reemplazar componentes de forma segura, que permita incorporar nuevas funcionalidades o corregir errores existentes. Para ello, en esta tesis se ha elaborado de un marco de trabajo para dar soporte a reemplazos de componentes de forma segura, entendiendo como tal que el hecho de que no se produzcan ejecuciones incorrectas debido a la ejecución concurrente de multiples tareas, asi como el garantizar los tiempos de ejecucion de cada tarea y acotar la duración temporal de los reemplazos. El marco de trabajo propuesto está basado, pues, en componentes de tiempo real, que tiene en cuenta los requisitos temporales en la ejecución de los componentes del sistema y de las tareas propias del marco que dan soporte a estos mecanismos de reemplazo. Este marco de trabajo incorpora un modelo generico de componente con tareas de tiempo real, un modelo de reemplazo de componentes cuyos tiempos de ejecucion son conocidos y limitados en tiempo y diferentes estrategias de aplicacion de dicho modelo de reemplazo de componente. Las contribuciones propuestas integran el analisis de la planificabilidad de los componentes del sistema y de las tareas del marco de componentes para permitir establecer los parámetros de reserva de los recursos necesarios para las tareas del marco. Por último, se realiza una validación empírica en la que se comprueba experimentalmente la validez del modelo tanto de forma genérica como en un escenario específico y determinando también los recursos necesarios para su implementación