# Virtual Reality-Based Interface for Advanced Assisted Mobile Robot Teleoperation
## 3 Results
### Usability Analysis Results  
Similar to [68; 69; 70], several methods, such as the usability tests of applications, which are traditionally used to validate hardware and software, together with users' interviews, were conducted to show the advantages of the proposed approach. Remark that most of the works proposing a new virtual reality interface for robot applications show its performance for just one user. However, there are few researchers that conduct some kind of usability test to prove its performance with several participants. For instance, in [7], a virtual reality application for the teleoperation of military mobile robotic systems was presented, and 15 participants were considered to prove its performance. Figure 8: Case study 2: frames of the video showing a trap situation. (**a**) video: 2 min 20 s. (**b**) video: 2 min 32 s. (**c**) video: 2 min 42 s. (**d**) video: 2 min 55 s.  
Figure 7: Case study 2: frames of the video showing obstacle avoidance situations. (**a**) video: 0 min 45 s. (**b**) video: 0 min 56 s. (**c**) video: 1 min 8 s. (**d**) video: 1 min 19 s. (**e**) video: 1 min 28 s. (**f**) video: 1 min 38 s.  
In [71], 10 participants were considered to validate a human-robot collaborative control in a virtual reality-based telepresence system. Finally, in [9], 11 participants were used to validate the mixed reality interface developed for robot teleoperation. Note that the mentioned works considered a similar number of participants, ranging from 10 to 15 participants, and with an average value of 12. Therefore, 11 participants were selected in this work for the usability and presence questionnaires. It is important to remark that considering a specific sample size gives rise to a certain margin of error [72]. In particular, for a sample of 11 participants and considering a confidence level of 95% and unlimited population size, the margin error is only 29.55%, which means that there is a 95% chance that the real value is within \(\pm\)29.55% of the value obtained with the selected sample, which is fairly reasonable. Furthermore, in order to have a representative sample, the 11 participants selected for the comparison experiment had different backgrounds. The main information about these participants is the following: 54.55% of the participants were female, whilst the remaining 45.45% were male; it was pretended to cover the maximum age range such that 18.18% of the participants were under 18 years old, 18.18% of them were between 18 and 40 years old, 18.18% of them were between 40 and 55 years old, 27.27% of them were between 55 and 70 years old, and 18.18% of the participants were older than 70 years old. With respect to their level of studies, 72.73% of the participants indicated basics studies, 18.18% of them indicated bachelor studies, and 9.09% of the participants indicated post-grade studies. In addition, 81.82% of the participants indicated that they had never used virtual reality headsets, whilst the remaining 18.18% of them indicated to have some experience with virtual reality applications and devices. Moreover, 63.64% of the participants indicated not having experience with video games and/or gamepad devices, whilst 36.36% of the participants indicated being video game players. The procedure followed to conduct the tests was as follows. Firstly, a brief description of the virtual reality devices and robotic applications was given to each participant. Note that the task to be performed was to guide the mobile robot to a certain location to perform a rescue operation in the shortest possible time in an unknown environment. Hence, in second place, training was performed by each participant to become used to the VE and the control device (i.e., gamepad controls). In this case, the same scenario shown in Section 3.1 (see Figure 3a) with the Gazebo-based robot model was used. The training took around 15 min per participant. After the training, the participant performed the required \"rescue operation\".