Towards Plug-n-Play numerical control for Reconfigurable Manufacturing Systems

Modern manufacturing systems require fast and effective adaptation to fluctuating market conditions and product diversification. This high level adaptability can be achieved through the utilization of Reconfigurable Manufacturing Systems (RMS), which should be based on modular equipment that is easily integrated, scalable, convertible in terms of functionality, and self diagnosable. RMS also necessitate the use of a dynamic controller architecture that is distributed, fully modular, and self configurable. In this paper, we present a control system design approach for reconfigurable machine tools through the use of modularized and decentralized CNC control. Specifically, we investigate design challenges for Plug-n-Play automation systems, where new system functionalities, such as adding new axes in existing CNC units, can be introduced without significant reconfiguration efforts and downtime costs. We propose a fully decentralized motion control architecture realized through a network of individual axis control modules. Reconfiguration of motion control systems based on this architecture can be achieved by only presenting the controller on each axis with information about machine configuration and the type of axis. This effectively enables modularity, reconfigurability, and interoperability of the machine control system. Finally, we present an implementation of the decentralized architecture based on the use of a real-time operating system, wireless networking, and low-cost ARM Cortex-M3 MCUs; we illustrate its effectiveness by considering machining of a standard test part defined in ISO 10791-7 using a software-in-the-loop testbed.