Open architecture control system for a modular reconfigurable machine tool.

Abstract

The present day manufacturing environment has forced manufacturing systems to be flexible and adaptable to be able to match the product demands and frequent introduction of new products and technologies. This research forms part of a greater research initiative that looks at the development of the reconfigurable manufacturing paradigm. Previous research has shown that the lack of development of a Modular Reconfigurable Manufacturing Tools (MRMT) and Open Architecture Control System (OACS) is currently a key limiting factor to the establishment of Reconfigurable Manufacturing Systems (RMS), which has been the primary motivation for this research. Open Architecture (OA) systems aim to bring the ideas of RMS to control systems for machining systems. An OA system incorporates vendor neutrality, portability, extendibility, scalability and modularity. The research has proposed, designed and developed a novel solution that incorporates these core principles allowing the system to be flexible in mechanical and control architectures. In doing so, the system can be reconfigured at any time to match the specific manufacturing functionality required at that time thereby prolonging the lifecycle of the machine via multiple reconfigurations over time, in addition to decreasing the cost of system modifications due to a well-defined modular system. The reconfiguration and machining variance is achieved by the introduction of mechanical and control modules that extend the Degrees of Freedom (DOF’s) available to the system. The OACS has been developed as a modular solution that links closely to the existing mechanical modularity on the RMT to maximize the reconfigurability of the system. The aim was to create a one to one link between mechanical and electronic hardware and the software system. This has been achieved by the addition of microcontroller based distributed modules which acts as the interface between the electro-mechanical machine axes via hardwired signals and the host PC via the CAN bus communication interface. The distributed modules have been developed on different microcontrollers, which have successfully demonstrated the openness and customizability of the system. On the host PC, the user is presented with a GUI that allows the user to configure the control system based on the MRMT physical configuration. The underlying software algorithms such as, text Interpretation, linear interpolation, PID or PI controllers and determination of kinematic viability are part of the OACS and are used at run time for machine operation. The machining and control performance of the system is evaluated on the previously developed MRMT. The performance evaluation also covers the analysis of the reconfigurability and scalability of the system. The research is concluded with a presentation based on conclusions drawn from the research covering the challenges, limitations and problems that OA and RMS can face before MRMT become readily available for industry.