The definition of equipment and components of physical plants is a necessary step towards the development of simulation, control, and supervisory applications for the petrochemical industry. Often it happens that the same plant/equipment is (re)modeled on each application, thereby there is a waste-of-time on repetitive (re)design. Even though each software platform normally offers a different view of the same plant, it is desirable to have some kind of interoperability between them. This paper presents M4PIA, a Model-Driven Engineering (MDE) infrastructure devoted for petrochemical industry automation. M4PIA allows representing industrial plants by means of different and interchangeable object-oriented models, providing means to perform automatic code generation from a plant specification for different software platforms. Currently, our work involves using M4PIA in high-level automation manouvers and plant simulations. The use of M4PIA is expected to result in less development time and costs, while it increases efficiency, maintainability, and reliability of the developed applications.

Wireless Sensor Networks (WSN) and Unmanned Aerial Vehicles (UAVs)have become two established technologies for applications such as monitoring, event detection, target tracking and remote sensing. WSN usually consists of hundreds and thousands of battery powered tiny devices that measure and collect data from its surrounding environment and forward it to a base station or sink. UAVs are a great platform for collecting remote data and can easily carry and deploy sensor nodes. The present research work focuses on the experimental validation of the so-called Efficient Geometry-based Localization (EGL) technique, which provides a flexible, scalable, and distributed way to localize static sensor nodes on an experimental field. The mobile sink node will be carried by an UAV system with autonomous flight embedded with a low cost Global Navigation Satellite System (GNSS) receiver. Experimental results comparing localization with standalone GNSS and Real Time Kinematic (RTK) GNSS technique validate the EGL technique at the end.

The continuous growth of IoT devices that use the 2.4 GHz radio spectrum has motivated research about spectrum occupancy, mainly the dynamic assignment optimization problem of the ISM band. For example, IEEE 802.11-based networks are easily interfered with, due to coexistence with other 2.4 GHz wireless networks, such as IEEE, 802.15.1 and IEEE 802.15.4-basednetworks. This problem causes a degraded performance of these wireless networks, especially inhighdensity areas where several APs (Access Points) are located in the same area to increase throughput. This paper presents MFDCA (Multi-Factor Dynamic Channel Assignment), which is a dynamic channel assignment modular approach for Wi-Fi networks. MFDCA channel assignment is a hybrid modular scheme that can be applied to centralized and distributed design networks. This approach can be used to assign all IEEE 802.11b/g/n standard channels (overlapping and nonoverlapping), and also includes an interference analysis module which uses a number of factors that may affect the transmission quality, such as signal receiver strength indicator (RSSI), signalto interference plus noise ratio (SINR), link quality (LQ), and overlapping factor (OF). MFDCAwas evaluated in a real testbed and results showed that it reduced the packet loss rates (lessthan 5.3%) and improved the quality and reliability of network traffic throughout (29-32 Mbits/s), requiring relatively low sensing process complexity and considering in assignment overlapping and non-overlapping channels from IEEE 802.11 standard.

With the advent of low-cost embedded platforms, the design of embedded systems has gained in popularity over the recent years. It also contributed to increase the popularity and availability of software libraries developed for embedded systems, such as Intels MRAA and its higher-level version UPM. Besides this evolution, the design of embedded systems that requires controlling complex physical devices (namely Cyber-Physical Systems - CPS) still needs attention from the research community. Model Driven Engineering has been applied as a possible solution to help the development of these highly complex systems. However, analyzing the existing MDE design tools, it is observed that there is a little support to the automated design of the sensing and actuation subsystems. For this reason, the present paper provides a MDE solution that allows the designers to represent and integrate the sensing and actuation subsystems on the applications, using as input a sensors and actuators library and a functional specification of the control system. The proposed approach applies a transformation process that aims to guide the designer to bind the control specification to the proper sensors and actuators belonging to the library. The tool named ECPSModeling was developed to support the proposed activities, as detailed along the paper. The design of an Unmanned Aerial Vehicle (UAV) is used to illustrate the proposed approach.

This paper describes RBESP, a dual stack protocol designed as part of the communication infrastructure of a short-range Unmanned Aerial Vehicle (UAV). It aims at providing a reliable communication between the UAV and its base station and a best effort communication between the UAV and a WSN. RBESP targets two distinct communication requirements using the same communication transceiver. The other end of the communication link can be heterogeneous devices transmitting with the IEEE 802.15.4 standard, which is also used in the UAV transceiver. The paper details the software layers that implement both the reliable communication with the base station and the best-effort communication with the WSN nodes. Two different scenarios were implemented in order to allow RBESP evaluation. The first scenario consists of the UAV node communicating with spatially distributed sensors on the ground. In the second scenario, the UAV node delivers the collected data to the base station. Both communication scenarios are very different in terms of connection time and volume of transmitted data. Obtained results are presented and discussed along the paper.

Wireless Sensor Networks (WSNs) are rapidly becoming a necessary tool in many different application areas, such as environmental monitoring, security, safety, and so on. The heterogeneity of hardware is large, so there exists several different environments that support WSN programming. However, the great majority of such environments only target the sensors programming, forgetting about their real intent: the application. In this paper we propose an approach to satisfy the need of high level development methods in WSN applications, aiming to provide a clear link between the modelled WSN constraints and the programming entities. An important part of this proposal is the so-called Wireless Sensor Network (WiSeN) Profile, an UML profile devoted for WSN applications design in a Model-Drivel Development (MDD) paradigm.

The adoption of dense industrial wireless network technologies in industrial plants is mandatorily paired with the development of methods and tools for connectivity prediction. These can be used to certify the quality (or reliability) of network information flow in industrial scenarios characterized by harsh propagation environments. Connectivity prediction must account for possibly coexisting heterogeneous radio access technologies as part of the internet of things (IoT) paradigm and easily allow post layout validation steps. The goal of the paper is to provide a practical evaluation of relevant coexistence problems between IEEE 802.15.4 and IEEE 802.11 networks, adopted here as widely used industry standards. Two different scenarios are tested with different radio platforms. Experimental results highlight the tolerable interference levels and sensitivity thresholds under different channel overlapping scenarios.

The growth of applications developed with the support of model transformations makes reuse a required practice, specially when applied to transformation assets (e.g. transformation chains, algorithms, and configuration files). In order to promote reuse one must consider the different implementations, communalities, and variants among these assets. In this domain, a couple techniques have been used as solutions to adapt reusable assets for specific needs. However, so far, no work has discussed their combined use in real software projects. In this paper, we present a new tool named WCT, which can be used to adapt transformation assets. Moreover, through lessons learned in industry, we address some reuse techniques devoted to adapt these assets.

Achieving RF connectivity is a critical issue in any wireless application. This is particularly challenging in mobile applications, as links are up and down many times. In such scenarios, where nodes keep on moving, it would be interesting for them to have knowledge of their remaining RF connectivity time. Such information can be used, for instance, to improve existing network protocols. The current paper addresses this problem by presenting the so-called Oriented Birth-Death (O-BD). The proposed solution is a modified version of the existing Birth-Death (BD) prediction model. We introduce in this work the notion of orientation to represent a tendency in the link future state. In other words, it considers if the link tends to increase or decrease the signal strength to make the prediction. Thereby a considerable prediction improvement is obtained, as shown in the evaluation performed. The proposed solution is well suited for mobile wireless sensor networks, whose nodes have low computational power and should be energy harvesting.

This paper presents a new routing protocol named RACE (network conditions Aware geographical forwarding protocol for real-time applications in mobile wireless sensor networks) that was developed to address the challenges found while using WSNs in a running competition scenario: QoS, mobility, and high workload. RACE aims to provide QoS requirements to the application layer by giving priority to real-time messages and also by handling network congestions. Routing is performed node-by-node, where each node calculates a score to choose the best node to forward the message. The main feature of our protocol is to also consider network conditions for calculating the score. Our simulation experiments show that RACE presents excellent performance in respect to message delivery ratio (up to 95%) and deadline miss ratio (7% in the worst case). For instance, we compared RACE with a well known protocol and observed that it outperformed this protocol in both metrics.

Link quality estimation is a fundamental building block for the design of several different mechanisms and protocols in wireless sensor networks. The accuracy of link quality estimation greatly impacts the efficiency of these protocols. Therefore, a thorough experimental evaluation of link quality estimators (LQEs) is mandatory. This motivated us to build a benchmarking testbed-RadiaLE, that automates LQEs evaluation by analyzing their statistical properties. Our testbed includes (i.) hardware components that represent the WSN under test and (ii.) a software tool for setting up and controlling the experiments and also for analyzing the collected data, allowing for LQEs evaluation. To demonstrate the usefulness of RadiaLE, we carried out a comparative performance study of a set of well-known LQEs.

Designing safety critical systems is a complex task due to the need of guaranteeing that the resulting model can cope with all the functional and non-functional requirements of the system. Obtaining such guarantees is only possible with the use of model verification techniques. This paper presents an approach aimed to fulfill the needs of critical system design. The proposed approach is based on the Architecture Analysis and Design Language (AADL), which is suitable to describe the system's architecture. A sequence of model transformations facilitates the verification of the designed AADL model and so assures its correctness. It must be highlighted that this is not performed in a single step, as it is possible to verify AADL models with different abstraction levels, which allows successive refinements in a top-down approach.

Autonomous, active components like smart sensors and actuators offer the capabilities of spontaneous behaviour, concurrent computations and well-defined communication interfaces. The perspective of building a system from such active blocks however has an impact on modeling and deployment of the components and supporting their interaction at run-time. The paper presents a modeling approach for dynamically interacting autonomous objects addressing the problems of independent development, deployment and incremental extension. Compared to related approaches our concept further complements the modeling by an adequate middleware that supports the abstractions of the model during run-time and performs the respective dynamic binding and co-operation between objects. This opens a wide range of possibilities for dynamically integrating hardware and software components and support virtual sensors and actuators.

This paper presents a model predictive controller (MPC) structure for solving the path-tracking problem of terrestrial autonomous vehicles. To achieve the desired performance during high-speed driving, the controller architecture considers both the kinematic and the dynamic control in a cascade structure. Our study contains a comparative study between two kinematic linear predictive control strategies: The first strategy is based on the successive linearization concept, and the other strategy combines a local reference frame with an approaching path strategy. Our goal is to search for the strategy that best comprises the performance and hardware-cost criteria. For the dynamic controller, a decentralized predictive controller based on a linearized model of the vehicle is used. Practical experiments obtained using an autonomous ldquoMini-Bajardquo vehicle equipped with an embedded computing system are presented. These results confirm that the proposed MPC structure is the solution that better matches the target criteria.

This work investigates the problem of scheduling network resources in the context of a cooperative mobile multi-robot system that exchanges messages with firm real-time constraints using a wireless network compliant with the recently created IEEE 802.11e amendment. Given the physical characteristics of wireless communication, message retransmission becomes a crucial issue, especially in a realtime application. Experiments performed in the context of this work show that the regular approach for retransmission proposed in the IEEE 802.11e is not suitable for real-time applications that require a certain level of reliability. To tackle this problem, the current work proposes a new mechanism called Integrated Scheduling and Retransmission Approach (ISRA) that integrates messages scheduling and retransmission in a unified manner at the MAC layer. Our proposal is able to deal with residual transmission errors and thereby increases the reliability level of the real-time messages. Our approach is evaluated through simulations for different scenarios of traffic load and compared with the standard approach of the 802.11e for scheduling and retransmission of real-time messages. Obtained results show that ISRA presents a high adaptability and does not get affected by variations in the network load or topology.

Modern real-time applications are very dynamic and cannot cope with the use of worst case execution time to avoid overload situations. Therefore scheduling algorithms that are able to prevent timing faults during overload are required. In this context, the value parameter has become useful to add generality and flexibility to such systems. In this paper, we present the scheduling algorithm called DMB (dynamic misses based), which is capable of dynamically changing tasks value in order to adjust their importance according to its timing faults rate. The main goal of DMB is to allow the prediction of timing faults during overloads and thereby support a dynamic tuning of tasks fault rate. It is used to enhance the features of the previously defined TAFT (time-aware fault-tolerant) scheduler. Obtained results show that DMB in conjunction with TAFT reached the most promising results during overloads, allowing to control tasks degradation in a graceful and determined way

The object-oriented paradigm has become popular over the last years due to its characteristics that help managing the complexity in computer systems design. This feature also attracted the embedded systems community, as today's embedded systems need to cope with several complex functionalities as well as timing, power, and area restrictions. Such scenario has promoted the use of the Java language and its real-time extension (RTSJ) for embedded real-time systems design. Nevertheless, the RTSJ was not primarily designed to be used within the embedded domain. This paper presents an approach to optimize the use of the RTSJ for the development of embedded real-time systems. Firstly, it describes how to design real-time embedded applications using an API based on RTSJ. Secondly, it shows how the generated code is optimized to cope with the tight resources available, without interfering in the mandatory timing predictability of the generated system. Finally it discusses an approach to synthesize the applications on top of affordable FPGAs. The approach used to synthesize the embedded real-time system ensures a bounded timing behavior of the object-oriented aspects of the application, like the polymorphism mechanism and read/write access to object's data fields

This paper tackles the problem of ever changing embedded systems non-functional requirements, specially the architectural ones. It proposes a solution based on features model and MDA standards, which is called features-oriented model-driven architecture (FOMDA). This proposal can be used to help application designer in defining the mappings and transformations of UML models to as many target platforms as wished. This is done by configuring model-to-model and model-to-code transformations over tiers, where every tier represents some target platform properties that the system must be mapped and transformed to. To validate the proposal a case study related to the development of an embedded real-time system is presented, detailing how to transform a generic high-level UML model to a model specific for a given target platform. Obtained results are optimistic and conclude that the FOMDA approach can make designers re-think their current development process to make it more decoupled from a specific target platform

This paper present a comparison between three different high-level modeling approaches for embedded systems design, focusing on systems that require dataflow models. The proposed evaluation investigates the facilities provided by these approaches for expressing systems requirements, functional specification, and timing constraints. Properties like model readability, testability, and implementability are also considered. Moreover, the support to different Models of Computation is also evaluated. A Crane Control System is used as case study to apply the proposed comparison criteria.

The growing complexity of today's embedded real-time systems demands new methods and tools in order to manage the problems of design, analysis, integration and validation of complex systems. This paper describes an object-oriented platform-based design process for real-time embedded systems. The proposed approach promotes a smooth transition from high-level UML specification to implementation, which is composed by hardware and software components. The transition from higher to lower abstraction levels is facilitated by the use of an OO realtime API, whose underlying facilities can be optimized according to the application needs and selected platform. An integrated toolset is used to support the intermediate steps of the design process. In order to illustrate the proposed approach and related toolset the design of an embedded real-time automation system for an "intelligent" wheelchair is presented.

The increasing complexity of current real-time applications demands systems to make good use of the available computational resources. Guaranteeing timing behavior using traditional real-time scheduling policies is turning to be unfeasible, as these policies are based in pessimistic worst-case assumptions that pre-allocate resources even though they will be rarely used. The time-aware fault-tolerant (TAFT) scheduler presents a flexible scheduling strategy that allows the construction of schedules maximizing the CPU utilization. This work presents the use of the TAFT scheduler with computational intensive distributed embedded applications, in order to keep a high ratio of successful tasks completion and so guaranteeing its computational progress. More specifically, the paper sketches a "TAFT-based" fusion algorithm for laser-scanner data and derives the requirements that the execution of this algorithm has on the CPU-scheduling.

The recent standard for the real-time unified modeling language (RT-UML) addresses the specification of real-time requirements and time using extended UML diagrams. It has a great potential to impulse the use of object orientation and UML in the development of real-time applications. This work evaluates the suitability of the RT-UML profile for modeling distributed real-time systems. The paper includes both a theoretical assessment of the proposed modeling concepts as well as it includes a case study, which is used to highlight the benefits and drawbacks from the adopted specifications.

Presents SIMOO-RT, an object-oriented framework designed to support the whole development cycle of real-time industrial automation systems. It is based on the concept of distributed active objects, which are autonomous execution entities that have their own thread of control, and that interact with each other by means of remote methods invocation. SIMOO-RT covers most of the development phases, from requirements engineering to implementation. It starts with the construction of an object model of the technical plant to be automated, on which user and problem-domain requirements are captured. Here, emphasis on modeling timing constraints is given. The technical details involved in the process of mapping problem-domain objects to design specific entities as well as the automatic code generation for the runtime application are discussed in the paper. Furthermore, details are given on how to monitor the runtime applications and to evaluate its timing restrictions.

This paper compares interaction and communication mechanisms used in distributed control systems, focusing on object-oriented and component-based development. The standard communication model used in distributed object oriented systems is remote method invocation. We argue that this client/server oriented model has some severe drawbacks when used in a control system where objects may have to broadcast information, spontaneously communicate environmental changes and where control autonomy is a crucial requirement. Therefore, we compare the traditional way of object invocation with a port-based scheme and the model of event channels. An application scenario from robot control is used to highlight similarities and differences among these mechanisms.

The increasing complexity in the development of real time systems leads designers to make use of techniques that help handle the complexity. One method to deal with complexity that became popular in the last years is the use of the object oriented paradigm. Some advances in hardware technology have made it possible to overcome the overhead problems that prevented its adoption in the past. The paper describes an integrated software environment called SiMOO-RT, developed under the context of ADOORATA project (A Distributed Object-Oriented Architecture for Real-Time Automation), a Brazilian-German cooperation that guides designers to explore the whole phases of a real time software development under the object oriented paradigm. The main features of the tool are presented and validated by means of a case study and future directions of the project are highlighted.

The paper presents a novel approach to the automatic identification of objects/classes from a system specification. The methodology is aimed at the development of distributed real time systems (DRTS), especially those conceived for industrial automation applications. UML is used as the modeling language in conjunction with an extended version of traditional DFD (E-DFD), that conveys information on flow type (data or control) and on process complexity and timing constraints. E-DFDs are mapped into a graph and a tool is used to carry out an automatic graph partition, which allows the identification of a set of objects that constitute, from the design and test points of view, the 'best-fitted' architecture. To validate the proposed methodology, a case study is presented and analyzed, comparing two design strategies.

This paper describes a powerful integrated development environment that covers all steps of the development of an object-oriented real-time application from initial design to the final evaluation. The system consists of a set of integrated tools for modeling, simulation, implementation, instrumentation, monitoring, and visualization that all work on the same OO system model. As all steps of creating a running implementation with visualized monitoring output from the design model are automatic, the environment encourages an iterative approach to the design of complex real-time control applications. This complete environment has been accomplished by integrating the SIMOO-RT modeling, simulation and implementation environment, developed at the Federal University of Rio Grande do Sul, with the Jewel++ object-oriented instrumentation and monitoring tool from GMD, St. Augustin, Germany. The work has been done in the context of the ADOORATA project (A Distributed Object-Oriented Architecture for Real-Time Automation), a Brazilian-German cooperation.