# A Roadmap to Integrate Digital Twins for Small and Medium-Sized Enterprises
## 5 Conclusions  
The interest from SMEs to I4.0 has grown exponentially in the last decade. This paper proposed a guideline for SMEs to adopt I4.0 technologies into their existing models in order to reap the benefits of DT and DTH models.  
In doing so, this paper aimed to answer two key questions regarding the design of the database management and data analytics, the flow of data through sensors and networking, digitization and systems integration in relation to SMEs.  
The communication framework composed of multiple components that each handle data capturing, conditioning, formal conversions and data transmission and aggregations. The final step was to present the data in a manner usable by management. A key challenge of this article has been the integration of these components in a manner that extracts and maps the I/O data between physical assets and their digital models.  
It was important to determine what data were to be collected based on their relevancy to the productivity or the goal of the complete system. We also noted that aggregating data from different sensors, different sources, and of different types can easily lead to errors in DT modelling, PLM, and real-world decision making. As such, it was paramount to understand the parameter being measured and the format this data would take to avoid these errors.  
The digitisation process was completed in two stages: the systems model, and the 3D digital model. Each served the purpose of modelling the behaviour and modelling the asset, respectively. Challenges of digitisation revolved around connecting the software to external sources in such a way that it was possible to run a continuous simulation which would adapt to changing external factors. The approach taken by this article was to utilise various software with a preference for low-cost, low-code, and open-source options where possible. This has been accomplished with the use OPC UA protocol, 3 DExperience, Modelica, Nodered and MySQL.  
Despite the benefits offered by DT and I4.0 technologies, there are many factors that SMEs need to be aware of. First and foremost are costs. Although we have outlined low-cost options in this article, costs in the form of software and expertise will inevitably arise due to the complexity and scale of the system. It is up to the SME to perform a cost-benefit analysis of their specific circumstance and evaluate whether such costs justify the long-term benefits. Furthermore, a patchwork integration of different platforms can create difficulties in verifying accuracy of modelling and simulation.  
Conceptualization, A.Y., T.Y.P., C.-T.C. and M.M.; methodology, A.Y., T.Y.P., C.-T.C.; software, A.Y., C.-T.C.; validation, A.Y.; formal analysis, A.Y.; investigation, A.Y.; resources, T.Y.P. and M.M.; writing--original draft preparation, A.Y., and T.Y.P.; writing--review and editing, T.Y.P., C.-T.C., and M.M.; visualisation, A.Y.; supervision, T.Y.P., C.-T.C. and M.M.; project administration, T.Y.P. and C.-T.C.; funding acquisition, T.Y.P. and M.M. All authors have read and agreed to the published version of the manuscript.  
This research was supported by the Defence Science Institute, an initiative of the State Government of Victoria, grant number CR-0032.