Digital Twin Framework for Multi-Tank Systems with OPC UA Interoperability and Real-Time Control and Visualization

This paper presents the design and evaluation of a digital twin framework for a nonlinear multi-tank control system, relying entirely on open-source technologies. A key component of the architecture is a custom-built OPC UA aggregating server, developed with the open62541 library and deployed on a low-cost single-board computer. This server acts as a bridge between the physical system and digital models, republishing real-time measurements and estimating unmeasured functionalities into Godot via GDExtension, which enables an interactive 3D digital twin. Experimental validation showed high agreement between the real system and the digital models, with correlation coefficients above 0.96 and low MAE and RMSE values. These results highlight the effectiveness of the proposed open-source OPC UA-based architecture for real-time monitoring, simulation, and control in cyber-physical systems.