# Virtual Reality-Based Interface for Advanced Assisted Mobile Robot Teleoperation
## 3 Results
### Case Study 1: Virtual Application Functionalities and Behavior  
A first experiment was conducted to show the proposed VE and its functionalities, which can be played in [66]. In this case, the Turtlebot3 Burger model using the Gazebo simulator was used, and the environment consisted of a cylinder obstacle and four rectangles defining the allowed square region; see Figure 3a. In particular, Figure 4 shows several frames of this experiment, whilst Figure 5 shows the trajectory and control performance of the overall experiment. The user can activate the 2D map option to see an orthogonal representation of the environment with the \"discovered objects\", and the location of the robot and the reference; see Figure 4a. The user is able to activate the task information data, e.g., robot velocity or target distance, at any moment; see Figure 4b. Note that these data depend on the application, and it would be easy to add the required information into the panel. Figure 4c shows the teleporting functionality. We remark that when this option is activated, the user cannot move the robot reference for security reasons. The obstacle avoidance capability can be seen from Figure 4c-f. Note that even though the user guides the reference through the cylinder obstacle, the robot successfully avoids this obstacle and reaches the reference when possible. This behavior can be better seen in Figure 5a,b. The repulsive force of the potential field-based navigation method becomes active around time instant 57 s when the distance \(\rho\) between the detected obstacles and the mobile robot boundary becomes lower than threshold \(\rho_{0}\), see Figure 5a and Equation (2), causing the robot deviation from the trajectory marked by the reference (see Figure 5b). Note also that when the mentioned repulsive force is deactivated, i.e., when the distance \(\rho\) between the detected obstacles and the mobile robot boundary becomes larger than threshold \(\rho_{0}\) (see Equation (2)), the robot returns to the path of the reference. Note that a so-called \"trap situation\" arises around time instant 115 s, i.e., the forward and angular velocities of the mobile robot are approximately zero; see Figure 5a. This is due to the fact that the robot has reached a corner; see position \(X=Y=2.5\) m in Figure 5b. Remark that these trap situations are typically present in potential field-based control schemes, and could be overcome if the user \"helps\" the robot in guiding the reference to an area reachable by the robot.  
Figure 3: Experimental setup: remote environment. (**a**) Simulation setup. (**b**) Real setup.  
Figure 4: Case study 1: Frames of the video showing the functionalities of the proposed VR-based interface. See the video in [66]. (**a**) video: 0 min 16 s. (**b**) video: 0 min 21 s. (**c**) video: 0 min 39 s. (**d**) video: 0 min 43 s. (**e**) video: 0 min 49 s. (**f**) video: 0 min 57 s. (**g**) video: 1 min 00 s. (**h**) video: 1 min 05 s.  
In the video recording, the 3D sound effect can also be appreciate, i.e., both servo sounds and warning sounds are local to the robot, and the user perceives these sounds differently depending on the distance between the robot and the user.