# A Survey on Multi-User Conversational Interfaces
## 4 Capturing Multi-User Conversational Interfaces
### Application Domains and Examples
#### 4.1.3 Service Robots  
In [PERSON] et al. [10], the authors present a dialogue-based robot service that can provide relevant services to multiple users simultaneously utilising a service-scheduling scheme. Although the available services are not explicitly mentioned in the paper, the author presents an example use case where the robot can provide weather information. Moreover, [PERSON] et al. [21; 22] describe scenarios in which a robot bartender is designed to handle tasks such as taking customer orders and serving drinks. It also incorporates socially appropriate behaviours, including greeting customers and responding politely to expressions of thanks. While it does not physically serve drinks, it uses gestures to simulate this action, facilitating realistic multi-user human-robot interactions for research purposes. The primary goal of the system is to effectively engage, maintain, and conclude interactions with users, providing a balanced integration of functionality and social interaction. In the specified scenario, the robot bartender was able to interact with two users.  
[PERSON] et al. [12] present the social robot Tangy, which is capable of planning, scheduling, and facilitating group-based recreational activities. This involves two key objectives: first the planning and scheduling a series of recreational group activities throughout the day while taking into account the schedules of multiple users, and second the interaction with a group of users during these scheduled activities by offering both group-based and individualised assistance based on the current activity state and individual user needs. In this human-robot interaction scenario, [PERSON] is tasked with organising and running a series of bingo games. For this, [PERSON] schedules groups of individuals for different game sessions. Before each session, [PERSON] navigates to each user's location based on their schedule and invites them to attend the upcoming game, reminding them of the time and location. During game sessions, the robot takes on the role of a game moderator, calling out numbers and assisting players. [PERSON] effectively manages multiple users during the games and distinguishes players to provide individualised assistance when required. Although the robot was able to interact with a range of 4-20 users, conversations were not always conducted simultaneously.  
In the work of [PERSON] et al. [23], interactions between a robot and three users within a domestic scenario are observed. The robot functions as a shared smart home application, primarily serving a cleaning task. Here, the focus is set on the examination of various control schemes in the context of multi-user interaction. The authors set up a shared living environment and study small groups of three people, such as roommates or family members, who are accustomed to sharing household devices. To create a realistic setting, a desktop model of an apartment is designed, with common spaces including a living room, kitchen, and bathroom, as well as individual bedrooms. It is examined how users interact with the robot in different scenarios, including cases where all participants share a joint goal of cleaning communal spaces, and situations with conflicting cleaning goals that can occur if each person wants their room cleaned first.