A Real-Time Control Network for Small Batch Part Manufacturing

Abstract

This paper reports on the development of a real-time Control Network as an integrated part of a shop floor control system for small batch part manufacturing. The shop floor control system, called the Production Control System (PCS), was developed by the ESPRIT 809 project. The PCS aims at an improved control of small batch part manufacturing systems, enabling both a more flexible use of resources and a decrease of the economical batch size. For this, the PCS integrates various control functions such as scheduling, dispatching, workstation control and monitoring, whilst being on-line connected to the production equipment on the shop floor. The PCS can be applied irrespective of the level of automation on the shop floor.

The Control Network is an essential part of the PCS, because it provides a real-time connection between the different modules of the PCS, which are geographically distributed over the shop floor. An overview of the requirements of a control network is given and the design is described with reference to the physical layout of the network, the protocols used and the services developed to guarantee the integrity of the PCS as a whole.

A prototype of the PCS and the Control Network has been installed and tested in the pilot plant of the ESPRIT 809 project. The Control Network has proven that it can supply a manufacturing environment, consisting of equipment from different vendors with different levels of automation, with a low cost, real-time and reliable communication facility.