## 2 Materials and Methods
### SMEs and Industry 4.0  
Article [31] highlights the need for digitisation and transformation to the Industry 4.0 level for SMEs. It points to them as being the key contributors in the industry. Digitisation  
Figure 3: Study results comparing Industry 4.0 technologies. for small- and medium-sized enterprises needs to be further explored, as these enterprises often have limited resources and can be overtaken by large participants. The implementation of Industry 4.0 technologies will open up new possibilities and opportunities for these companies and make them more competitive in the industry. On the contrary, without implementation, difficulties in maintaining the industry can be expected. A case study [32] focused on a local automotive company that implemented some Industry 4.0 attributes. The company:  
1. implemented an ERP system as an internal and external platform for communicating with customers and suppliers and for improving decision-making processes (creation of the so-called \"Digital factory\"),
2. set up a multidisciplinary project team to improve products with customer input,
3. set up an integrated systems management unit to simplify the organisation and facilitate digitisation,
4. implemented logistics functions to improve responses to the international market,
5. set up staff training and set up a permanent training team [32]. Following the implementation of these attributes, revenue significantly increased and profits began to rise. Productivity and the resulting product quality have also increased significantly. The results of [6] show great potential for small- and medium-sized enterprises if they cooperate and exchange data. For example, in predictive maintenance, a huge amount of data obtained from production is the key. For small- and medium-sized enterprises, obtaining such an amount of data can be a problem, and they need to collect data for many years. If small- and medium-sized enterprises work together, they can accumulate sufficient data and be competitive with large companies. This is not only true for predictive maintenance; the results of the study also show energy savings for individual companies in such data collection. On the other hand, security issues need to be addressed with such data exchange. According to [4], by introducing Industry 4.0 technologies, SMEs can increase their organisational agility, adaptability and resilience to cope with a competitive environment. SMEs face three major challenges in terms of digitisation:  
1. technological challenges--Industry 4.0 infrastructure is a major challenge for SMEs given the scale, resources and expertise needed to integrate it. 2. trust challenges--Research has shown that SMEs, if they could collaborate and share critical data with each other and with partners, would be able to gather the necessary amount of data faster, e.g., in terms of predictive maintenance. This would result in opportunities for asymmetric learning. On the other hand, business managers would find such cooperation difficult. 3. the Big Data challenges--as Industry 4.0 technologies generate and require the processing of vast amounts of data, SMEs may have difficulty storing, analysing and transforming data into efficient solutions [4]. As a framework to address these challenges, the authors suggest:  
1. incorporation of Industry 4.0 technologies, especially Big Data and Cloud Computing. The Cloud can offer computing power to process large amounts of collected data at a reasonable price. 2. building a structure providing standards for interoperability between different technologies and suppliers and communication between different channels [33]. 3. incorporation of communication protocols, security features on older systems and a set of uniform technical standards, providing a high level of credibility for SMEs in collaboration [4]. According to [34], Industry 4.0 technologies are created and used mainly by large companies; nonetheless, a large portion of suppliers are small- and medium-sized companies.