## 3 Results and Discussion
### Scientific Mapping
#### 3.2.1 Application Fields and Methods
The following exchange possibilities were investigated in the study: voice command, gestures, first-person vision, and physical controllers. Due to the variety of systems studied, several operations, such as air conditioning, navigation, telephone, and audio controls, were used by various studies in diverse contexts of use, command design, and visual representation. This limits the evaluation of the connection between the results obtained in the research [46; 48; 52], since the use of standard methods for usability testing would benefit from a thorough examination of the data and conclusions gathered from various investigations. Five studies (26%) reviewed industrial machinery manufacture. Three of them [15; 16; 45] were published by the same research group and focused on industrial power units, while the other two looked at hydraulic pump production [41] and specific machines for automation technologies [53], respectively. Seven (37%) of the studies did not indicate the field of application [19; 20; 40; 42; 44; 47; 51]. It is common for virtual-reality applications developed by an academic research team to be tested in their own laboratory with prototypes and artifacts [59]. Figure 5 is an example of a study conducted in a laboratory environment. In terms of the methods and metrics used, we identified that the studies focused on the accuracy of experimental results when compared to testing with conventional CAD models and physical prototypes. The articles under consideration spanned a broad range of methods and metrics. The main approaches used by the studies under examination are listed in Table 3.  
Despite the fact that the reviewed studies utilized a wide variety of methods for collecting qualitative and quantitative data, some of them were referenced in several studies. Three studies used the Time to Complete the Task metric. The Time to Complete statistic is used to calculate how much time each participant spent on each task. The qualitative data were often gathered by providing a standardized questionnaire to respondents after they completed the tests. The System Usability Scale questionnaire was often used to measure the perceived user-friendliness of the system with which the participant interacted. The SUS approach is frequently used in industry and is effective for system comparison [46]. Another often-used metric is the Number of Mistakes, in which moderators utilize visual observation to quantify the mistakes made by participants while performing tasks other than those for which they were trained. The Rapid Upper Limb Assessment score was used in two studies. The RULA is one of the most frequently used measures for assessing employees' exposure to ergonomic risk while performing manual upper body activities such hand, neck, and limb twisting [46]. The Sense of Presence Inventory (ITC) and User Experience Questionnaire (UEQ) are two methodologies worthy of note. The Sense of Presence Inventory is a metric used to examine how people perceive physical space (defined as \"a sense of physical placement in the mediated environment and interaction with and control over parts of the mediated environment\") [52]. The User Experience Questionnaire is used to obtain evaluations from participants on the following aspects: attractiveness (overall impression of the product), perspicuity (ease with which the product can be understood and used), efficiency (ability to use the product efficiently), dependability (the feeling of being in control of interactions), stimulation (excitement and motivation to use the product), and novelty (perception of the innovation and creativity of the product). Other methods and metrics were only referenced in one study, such as FMEA (failure modes and effects analysis), criticality analysis (CA), and expected final distance [53]; intuitiveness and task weight [45]; readability of information, command display, and function controls [44], as well as several others, such as heat maps, pupil diameter, heart  
Figure 5: A study conducted in a laboratory environment and using RULA score [44].