【文章內(nèi)容簡介】
systems present the advantage of improving performance, modularity, integrity and reliability while allowing incremental expansion without plete hardware replacement. It offers a promising alternative to control system architecture. This paper is dedicated to study a distributed machinetool architecture. It is based on intelligent devices interconnected on munication link. It is characterized by distributed tasks and distributed data, but with unique control access system. It is designed by using standard devices and FIP fieldbus and verified by a experimental implementation, in which the system controls a multiaxis machine to successfully execute a coordinated motion as well as to respond to sensors values changes. The paper is organized as follows. In section 2, the machinetool control system architecture is described. Section 2 gives a brief description of FIP and Section 3 outlines our experimental implementation. We conclude in section 4 with some general remarks and future research perspectives. 2. Machinetool control system architecture The machinetool control system is a realtime and multitask system. Its classical functional architecture is shown in . It consists of three units: user interface/supervisiou/programming unit, servo unit, and sensors/actuators unit. The main mission of this system is to control workpart machining. It includes two different and related tasks aspects: ●to ensure the precise trajectory and speed control of the mobile organs of machinetool. ●to survey the correct execution of this positioning (tracking) process, to react on environment changes as well as to perform the specified operations or actions upon machinetool mechanics. such as tool switching, cooling, lubricating, etc. Fig. 1 Functional architecture Chronologically, this mission is also divided into two steps: control program planning and control program executiug. In the first step, there is no direct action on machinetool multitask nature: “data acquisition and preprocessing” step. While in the second step, the control is effectively executed. It is worth to note that in the second step, the parallelization is possible due to the mechanics, only the motions as well as the operations to be performed are specified. This is the “data acquisition and preprocessing” step. While in the second step, the control is effectively executed. It is worth to note that in the second step, the parallelization is possible due to the multitask nature. fieldbus To meet the realtime munication need in our distributed machinetool, FIP is adopted. In this section, we briefly explain the main technical properties of FIP. FIP (Factory Instrumentation Protocol) is an industrial work designed for the exchange of information between sensors, actuators and control devices such as PLCs, CNCs or robot controllers. The architecture of FIP follows the socalkd reduced OS1 model (Physical layer, Data link layer and Application layer). This architecture makes a clear distinction between realtime munication and conventional message munication. At Data Link layer, there are services as