Retrofitting legacy systems for industry 4.0 via OPC UA and distributed control

Abstract

As manufacturing shifts towards Industry 4.0, enterprises are being pushed to invest in smart, Industry 4.0-capable hardware to streamline their production processes. In particular, Small and Medium Enterprises (SMEs) may be hesitant to adopt these new technologies due to the significant capital investment required. To support this, legacy hardware must be upgraded to an Industry 4.0 standard at a minimal cost. This introduces the concept of digital retrofitting. Many methods of digital retrofitting have been proposed in the past. However, many focused on a single aspect and did not focus on a wide range of machines in a production environment. This paper proposes a general digital retrofitting framework that can be applied to a large range of machines, using OPC Unified Architecture (OPC UA) as the standard for communication. The framework is applied in a layered approach, consisting of the asset layer, integration layer, and communication layer, following RAMI4.0 naming conventions. The framework is laid out in detail, focusing on giving individual machines control such that modular, distributed control is achieved. This work then implements the framework on a system consisting of two conveyors and two KUKA robots in the Laboratory for Industry 4.0 Smart Manufacturing Systems (LISMS) and discusses the results and solutions to any problems faced.