Isidro Calvo

Control communications with DDS using IEC61499 Service Interface Function Blocks

The IEC61499 is an open standard for distributed control and automation. The interface between control software and hardware or communications is achieved by means of the so-called Service Interface Function Blocks (SIFB). This paper presents the guidelines to build communication SIFBs based on the emerging OMG DDS (Data Distribution Service) middleware. This specification implements in a very efficient way the Publisher/Subscriber paradigm providing significant QoS configuration possibilities. These characteristics make DDS suitable for implementing the communications among time-critical devices. By using these DDS-SIFBs within IEC61499 code generation tools, the designers of the distributed applications will be allowed to use this powerful technology in the new distributed applications.

Building complex remote learning laboratories

The interaction with real plants is a key issue in control engineering education in order to consolidate the concepts learned in the classroom. Unfortunately, for several reasons, real laboratories are not always available. On the other hand, Internet technologies have proved to be mature and reliable, becoming a common alternative in the creation of remote laboratories. However, the use of these technologies in complex remote laboratories is not a trivial task as several requisites must be satisfied simultaneously. This article proposes a methodology that eases the creation of remote laboratories establishing the steps to build up a remote access system. This methodology proposes a set of key components that can be used to define the access to a remote plant from a functional point of view. Some of these components are generic being reusable in most applications whereas others are application specific. In summary, the methodology allows designers to concentrate more on the functionality of the applications than on the technical aspects of the underlying technology. The use of this methodology is illustrated with a relatively complex example: A laboratory manufacturing cell.

Supporting a reconfigurable real-time service-oriented middleware with FTT-CORBA

Modern distributed real-time systems (DRTS) are typically formed by several heterogeneous networked devices. Sometimes these devices must adapt to dynamic environments in which devices may join or leave the network and must respond in run-time to changing requirements ensuring certain levels of QoS. These characteristics yield to systems that are intrinsically complex to develop, test and maintain. In this scenario middleware platforms, and particularly Service-Oriented Architectures (SOA), are becoming increasingly popular because they ease the creation of complex distributed applications and reduce the time-to-market. In this paper we show how the recently developed Flexible Time-Triggered CORBA (FTT-CORBA) can be used to support real-time Service-Oriented Architectures that are deterministically and dynamically reconfigurable.

A Novel Synchronous Scheduling Service for CORBA-RT Applications

Although distributed real-time (RT) systems are intrinsically complex to develop and maintain, the use of certain object-oriented (OO) technologies such as CORBA and CORBA-RT facilitates those tasks. This is the main reason why these technologies are becoming increasingly popular. Moreover, CORBA is complemented with additional services that solve specific requirements for some applications, so developers may concentrate on the application functionality. Following this approach, this paper presents a new service that allows the synchronous scheduling of different activities in a distributed RT system in a simple and flexible way. This paper also explains how this service can be used for optimizing that access to shared resources in a distributed system and presents several experimental data that show the service performance

Object-oriented modeling for remote monitoring of manufacturing processes

Deals with the use of object oriented technologies in the modeling of industrial plants that have to be remotely monitored and/or controlled. The main goal is to propose a design methodology for obtaining the model of the so-called Virtual Plant, that a remote and certified user will use to access the real plant for performing command actions and/or monitoring. The type of applications and systems targeted must have autonomous behavior and be interconnected and accessible. Reliability, maintainability and flexibility are also required goals, as well as a high rate of reusability of the applications. The methodology has been applied to the remote process monitoring and control of manufacturing processes. The Virtual Plant Model is, in fact, the part of the plant that can be accessed by a certified remote client and thus it can be constituted by a set of sub-models, as many as different types of clients. The Virtual Plant resides inside the Application Server who is responsible of communicating with the cell controller and sends the image of the actual plant state (the Virtual Plant) as required by the remote client (monitoring) or sends the client commands to the cell controller.

Access to process data with OPC-DA using IEC61499 Service Interface Function Blocks

The need for flexibility in manufacturing systems is continuously growing. This need deals with the establishment of design methodologies for implementing distributed applications. The IEC61499 define a generic architecture for designing distributed applications, based on Functions Block (FB) networks. The interface between the control software and the hardware is achieved by means of the so called Service Interface FB. But guidelines to implement this type of FBs are provided neither by the standard nor by the available tools. On the other hand, one of the most widely used industrial communication standard is OPC that enables the exchange of data between multi-vendor devices and control applications without any proprietary restrictions. Thus, an easy integration of this communication standard within IEC61499 applications may contribute to consolidate such standard. This paper presents the guidelines to use OPC in industrial applications through the definition an implementation of SIFBs to access process data using OPC-DA (OPC Data Access) specification.

A Remote Laboratory for a Basic Course on Control Engineering

The current work presents a remote laboratory for a basic course in control engineering over which several experiments may be performed. The proposed experiments have been carefully selected in order to illustrate the maximum number of concepts learnt in the classroom over a unique plant, a Ball & Hoop system. In this work, Labview has been used to acquire and handle process data whereas OPC technology is used to connect remote servers with web-integrated front-end applications. This choice has been made on the basis that these tools do not require very advanced skills and may be a reasonable approach for a wide range of simple remote laboratories.

A time-triggered data distribution service for FTT-CORBA

FTT-CORBA is a middleware architecture aimed at synchronizing the task activations of a distributed system according to a plan that may be changed at runtime. In this architecture tasks are wrapped within CORBA methods that are activated by a central node, the Orchestrator, over a LAN. Previous versions of FTT-CORBA focused on CPU-bound applications in which the communication time was neglectable. However, in some cases, this assumption is not valid. This work presents an add-on service, integrated within the FTT-CORBA middleware, aimed at minimizing the interference among task activation and data distribution messages. By using this new service the Orchestrator will be capable of controlling the transmission of data distribution packages from the distributed nodes by dynamically allocating them in specific time slots.

Using object oriented technologies in factory automation

This paper discusses the use of OO technologies, in particular the use of Unified Modelling Language (UML) in factory automation. The authors have proposed an architecture to access remotely industrial plants. This papers focuses in the so-called virtual plant model, that contains the information of the plant that is remotely accessible. In order to show the use of UML class diagrams, the virtual plant model of simple manufacturing cell is developed. The remote actions are grouped in user profiles and from them the class diagrams that form the virtual plant are designed. The virtual plant model is contained in the application server that acts as a middleware between the plant and the remote users. Although these classes have been identified for a very simple case study, they may be extended and enriched according to the needs of new applications.

Developing CPPS within IEC-61499 based on low cost devices

The adoption of new technologies and automation standards, such as OPC-UA and IEC61499, is essential in order to satisfy the flexibility and reconfiguration needs required at the Factories of the Future. Currently, the Cyber-Physical Production Systems (CPPS) are at the core of the new control and automation distributed systems. However, it is necessary to provide the research community with low cost platforms capable of integrating these new technologies and standards for prototyping new products and concepts. This work presents a low-cost embedded architecture capable of providing process data by means of OPC-UA services, integrated as IEC61499 blocks. Thus, IEC61499 provides high-level capabilities by combining easily software components with independence of the hardware platform used.