# Integrating Digital Twins of Engineering Labs into Multi-User Virtual Reality Environments
## 2 Materials and Methods  
This research addresses and proposes the integration of virtual reality and real-time sensing technologies for the development of a collaborative, safe, and interactive environment, aimed at improving the learning experience of students in work that involves the use of high-capacity engines. To achieve this, the Design Science Research Methodology (DSRM) was used, recognized in the field of design science for its ability to systematically structure the research process. The following stages were considered: (1) Identification of observed problems; (2) Definition of objectives of a potential solution; (3) Design and development; (4) Demonstration; and (5) Evaluation. Figure 1 shows the stages, activities, and tools needed to carry out this research.  
During the first stage of the research, several tests of the trailed engine experiment, considered an essential component in the training of mechanical engineers, were carried out. This experiment is particularly relevant as it allows the study of the behavior of an internal combustion engine in the absence of phenomena associated with combustion and exhaust gases. In this context, the behavior of the students when participating in this experiment was analyzed, evaluating their level of interest and commitment in the laboratory, as well as the safety of the environment in terms of physical risks and possible future damage.  
Based on the above analysis, the opportunity to incorporate virtual reality technologies as an innovative solution was identified. Virtual reality not only provides a safer environment for conducting laboratory work but also increases student interest by incorporating modern technological tools [32]. Previous studies suggest that increased interest in the laboratory can translate into more effective learning and, ultimately, into the formation of more competent mechanical engineers better prepared for the challenges of industry.  
At this stage, an exhaustive analysis of the signals that are currently monitored in the engine was carried out, to preserve the essence of the experiment and guarantee correct sensorization. A real-time communication system was implemented between the sensors and Unity, the platform used for the development of the virtual environment [32; 33; 34; 35]. This process was divided into three phases: (1) analysis and correct sensorization of the engine; (2) effective real-time communication between the signals and a server; (3) implementation of the real-time signals in a multi-user environment.  
The implementation of these phases was essential to establish real-time communication to support the functionality of the proposed system.  
With the real-time sensing implemented, a multi-user environment was developed that included a scanned model of the engine used in the laboratory. In this virtual environment, interactive visualizations of the data captured by the PLC sensors were integrated, positioning them in the corresponding locations of the digital model. Subsequently, functional tests were performed to evaluate the accuracy and efficiency of the system.  
At this stage, a new laboratory experiment was carried out with students of different academic levels and different Academic Performance Index (IRA) scores. The participants completed both experiments, the traditional and the proposed one, and then answered a satisfaction questionnaire to measure their perception of the new technologies implemented. In addition, the variable of time spent in each modality was externally evaluated to compare the efficiency and effectiveness of both experiences.  
Figure 1: Methodology.