WiFLEX

FMFT - Flexible Manufacturing Field Trial

Within the European project R-Fieldbus, an industrial manufacturing field was developed. This field trial was conceived as a demonstration testbed for the technologies developed during the project, as well as for future teaching and research purposes. However, due to several reasons, its outdate became inevitable. This work describes the control application designed and the implementation procedures that took place in order to accomplish the objective of updating the manufacturing field trial, accordingly to the PROFIBUS DP standards and the actual industrial fieldbus technologies. Several software features, as well as a complete new application structure provided a fully modular base for present and future developments.

This work was part of Nuno Cruz and Ricardo Gomes first projects at CISTER / IPP-Hurray!, and represents only a short resume of the documentation written in scope of the FMFT - Flexible Manufacturing Field Trial.

Introduction

Between January of 2000 and July of 2002, with the common effort of several European educational and commercial institutions, the European R-Fieldbus Project (http://www.hurray.isep.ipp.pt/activities/rfieldbus/) was developed.

The main objective of the R-Fieldbus project was to support both the real-time requirements of control and status data as well as a user defined Quality of Service (QoS) for the multimedia communications. Additionally, it supported mobile industrial devices and interoperability with existing devices supported by wired industrial networks. Its architecture was based on the integration of boardband wireless technologies emerging at the time with existing industrial communication protocols such as those specified in the European Standard EN50170 [1].

To demonstrate the technical feasibility of the RFieldbus system in real industrial environments, its reliability, benefits for end-users and the opportunities for technology developers, two different field trials were developed. One was a process automation field trial at an oil refining plant. The other was a manufacturing automation field trial (http://www.hurray.isep.ipp.pt/activities/rfpilot/), built at the School of Engineering of the Polytechnic Institute of Porto (ISEP - Instituto Superior de Engenharia do Porto) under supervision of CISTER / IPP-Hurray! R&D Group.

One of the goals of the development of the manufacturing field trial was the possibility of future employment of the equipment for teaching activities and research in the areas of factory floor networks, automation and mobile robotics [2].

However, after four years since the conclusion of the project, the equipment of the manufacturing field trial suffered from lack of updates and the necessary flexibility to fulfill its new goals. To update the manufacturing field trial and introduce actual flexible industrial field technologies, several modifications had to be introduced to the manufacturing field trial to bring additional advantages both as a teaching platform and as a research test bed.

Objectives

The main objectives in this work are:

• Remove all deployed software and used prototype modules related with the R-Fieldbus project;
  
• Update the manufacturing field trial in order to encompass standard industrial fieldbus technologies;
  
• Introduce a new control philosophy based on a Programmable Logic Controller (PLC) instead of a PC application, therefore concentrating the main control application in a PLC that may be used for further developments;
  
• Implement a user-friendly and simple interface to control the basic operations of the system (start, stop, refill and unload operations);
  
• Provide a fully modular hardware and software base for further developments;
  
• Implement a fully modular software base and provide compatibility with the OPC standards;
  
• Optimize and assure reliability of the process.
  

System overview

Presently the FMFT uses a fairly complex system of actuators, exchange terminals (also called I/O Station), conveyer belts, infrared sensors, swivel arms, pneumatic electrical motors, programmable logical controllers (PLCs) and other industrial equipment as well as a group of lights to report system status.

The general purpose of the FMFT is to have several different objects traveling over the conveyer belts, be able to correctly identify and classify these objects and finally direct the objects to the appropriate container.

As it is visible in Figure 1, the system is composed by three conveyer belts for the objects to travel on, two swivel arms that are responsible for transferring objects between two conveyer belts and there are four different buffers to collect the different objects. The pneumatic actuators (or kickers) in the system are located in the Input Buffer area – this one will feed the objects into the system – and two in front of the output buffers for the white and black objects. The two boxes in the middle of each conveyer belt represent the two Color Detector and Classifier (CDC) Stations that identify and classify the moving objects. There are also three electrical closets that store several electrical devices like the PLCs, the motor drivers and the exchange terminals.