# Dialogue Enhanced Extended Reality:
## 4 Use Cases
### Use Case 1: Universal Robot's Gripper Maintenance  
We chose the maintenance of a Universal Robot's gripper as our first use case. Participants were assigned the task to perform a periodic inspection for the robot's gripper (the actual instruction manual can be consulted online in the following address: [[https://assets.robotiq.com/website-assets/support_documents/document/3-Finger_PDF_20190322.pdf?_ga=2.105997637.750885948.1563187207-129849](https://assets.robotiq.com/website-assets/support_documents/document/3-Finger_PDF_20190322.pdf?_ga=2.105997637.750885948.1563187207-129849)]([https://assets.robotiq.com/website-assets/support_documents/document/3-Finger_PDF_20190322.pdf?_ga=2.105997637.750885948.1563187207-129849](https://assets.robotiq.com/website-assets/support_documents/document/3-Finger_PDF_20190322.pdf?_ga=2.105997637.750885948.1563187207-129849)) 5031.1563187207/assets.robotiq.com/website-assets/support_documents/document/3-Finger_PDF_20190322.pdf, last accessed 29/05/2020--see section 7.3 _Periodic Inspection_), which is necessary to ensure its good condition and safe operation. In the experimental setup, the robot arm was placed over a table, fixed on a pre-set position, with the gripper coupled. The gripper was located about the chest-height of an average person and facing up, with its fingers closed, as shown in Figure 3. The tools needed for the task were placed on the working-table.  
Before each participant's session would begin, they were informed that they would have to complete a form for the system's assessment afterwards. At the beginning of the session, participants were invited to try and get familiarised with the hardware (in this use case, HoloLens Glasses were used for outputting visualisations). While doing this, a researcher would present the participant with the robot, the system, and the task at hand that they had to complete. Once the explanation was done, the task would begin.  
The completion of the task requires participants to operate with both hands, making it an appropriate task for the integration and testing of the proposed XR architecture. The set of instructions described in the manual is equivalent to a series of processes that require a single action to be performed by the user in each step. The compiled set of steps works as a base dialogue flow where each of the steps corresponds to a dialogue state. We added some extra steps to the flow to accommodate the system's contextual needs: an introductory step to define the state prior to the beginning of the task, and a final step to mark the conclusion of the interaction. Figure 4 shows the sequence of steps required to complete this use case's task. In addition, as the system can exploit the domain knowledge to guide the operator, knowledge about multiple question types that could arise during the task was included--what to do in the current step, how to do it, where are the involved parts or items, and so on.  
During the maintenance task, the IM decides which AR animation to render (pointing the location of bolts to unscrew or cables to connect or disconnect, showing the movement to perform to check the gripper's fingers, and so on). These animations are accompanied with aural responses and contextualised according to the current step in the maintenance process, for example, the bolts to unscrew are different in the decoupling step and the finger-opening step. Furthermore, the operator can explicitly ask to repeat an AR animation as many times as needed.  
Ten people (50% male, 40% female, 10% would rather not say their gender) participated in the testing of use case 1. A total of 50% were in the age range between 25 and 29, 30% between 35 and 39, 10% between 30 and 34, and 10% between 18 and 24. All the participants had European Spanish as one of their mother tongues. Participants were all volunteers working at the same centre where the prototype was developed and their data were treated anonymously (the operator appearing in Figure 3 gave consent to its use in this publication).