# Virtual Reality Training Application for the Condition-Based Maintenance of Induction Motors
## 4 Materials and Methods  
This section covers the design and development of the induction motor maintenance training application. In virtual reality, users learn through autonomous interaction, hands-on learning, and problem solving. For this purpose, an application was developed to take full advantage of the benefits that VR provides for training. The design of this learning experience aimed to provide (1) a realistic VR experience in which to learn and to practice the principles of induction motors and to identify some of its faults; (2) a safe environment where mistakes can be corrected; and (3) immediate feedback provided on operational learning. This design follows the idea that, rather than learning theory in a formal manner, the potential of VR lies in \"learning by doing\", which is often very difficult to apply in conventional classrooms. The application is conceived as a hands-on learning environment, which helps to increase interest in the material based on the students' preference for practice-oriented learning content rather than memorization. This application is structured into two modules: a first module, the emphasis of which is to learn about the components of an induction motor and arrangement design; and a second module, which emphasizes practicing the identification of induction motor failures (broken bars, misalignments, unbalances and gradual wear on gear teeth) and their influence on operability. Each phase of these modules uses different learning objectives as proposed in [PERSON]'s taxonomy [41]. The operational learning model used in this research is summarized in Figure 1, and its components are analyzed in detail in the following sections. Module A covers the identification of the fundamental components of induction motors and basic arrangements. In this module, the content was designed in a structured format to help users learn the components of an induction motor and integration in a kinematic chain comprised of different components besides the motor, such as gearboxes, generators, etc. These are concepts for which a higher degree of visualization and experiential awareness is required. Module A was designed so that users could progress through different levels and advance towards the following goals:  
* Introductory tutorial: In any immersive virtual reality training application, it is important for the user to have sufficient time to become familiar with the virtual reality devices. This familiarization period is important because the novelty of VR environments and interfaces can limit the user's learning experience, especially if such devices are new to the user. Therefore, these applications must include an extensive pre-training phase, in which students acquire sufficient knowledge through their interaction with the VR environment. This level is also used to train users in how the VR interface can be used, such as by grabbing and placing objects, and through a tutorial, in which the user, guided by the instructions that appear on the board, has to assemble a motor arrangement on the workbench, as can be seen in Figure 2. The procedure is simple: first, place the induction motor, then the DC generator and finally a coupling so that the system will function. In this way, this first level serves as an introduction to the devices, and some practical and operational knowledge is shared with the student. It also serves as a learning experience of the mechanics that will be used throughout the activity and familiarizes the user with the way the information is presented. Finally, it helps mitigate any initial reaction towards the VR environment, which can reduce user attention, if presented with relevant information early on;
* Disassembly of induction motors: Accurate knowledge of the components of an induction motor is essential for an understanding of its operating principles. VR provides a space with a higher degree of visualization than other less immersive environments, in which machines may be assembled and disassembled, and every part inspected in the context of the whole machine.