## 2 Background and Related Works
### Social Robots' Setting Applications: Public Environment
\begin{table}
\begin{tabular}{l l l} \hline \hline
**References** & **Robot** & **Study Design** \\ \hline \multirow{4}{*}{[PERSON] et al., 2008} & \multirow{4}{*}{FESTO} & Participants: 48 adults \\  & & No. of interactions: One-off interaction \\  & & Type: Autonomous \\  & & Measures: User experience \\  & & Evaluation: Questionnaires and interviews \\ \hline \multirow{4}{*}{[PERSON] et al., 2015} & \multirow{4}{*}{[PERSON]} & Participants: 26 visitors \\  & & Conditions: Intention estimation algorithm vs. \\  & & proactive vs. non-adaptive \\  & & No. of Interactions: Field trail Interaction \\  & & Type: Autonomous with WoZ controlled speech recognition \\  & & Measures: Interaction intention success rate \\  & & Evaluation: Video analysis \\ \hline \multirow{4}{*}{[PERSON] et al., 2016} & \multirow{4}{*}{Robovie} & Participants: 33 adults \\  & & No. of Interactions: One-off \\  & & Interaction Type: WoZ controlled robot \\  & & Measures: Naturalness, understandability, \\  & & perceived politeness and overall quality \\  & & of the robot’s deictic behaviours \\  & & Evaluation: Questionnaire \\ \hline \multirow{4}{*}{[PERSON] et al., 2005} & \multirow{4}{*}{Valerie/irobot} & No. of interactions: On average 88 per day for 9 months \\  & & Interaction type: Chat-bot storytelling \\ \cline{1-1}  & & Measures: Number of repetitive interactions, \\ \cline{1-1}  & & time of each interaction \\ \cline{1-1}  & & Evaluation: Log in data analysis \\ \hline \multirow{4}{*}{[PERSON] et al., 2018} & \multirow{4}{*}{PAL REEM robot} & No. of interactions: 200 pieces of user feedback \\ \cline{1-1}  & & Interaction type: Autonomous \\ \cline{1-1}  & & Measures: Number of positive replies from the users, \\ \cline{1-1}  & & Evaluation: Manual observations, questionnaires \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Summary of HRI studies in the work environment and public spaces mentioned in Section 2.3.  
field study that has been performed in a shopping mall is the one from [PERSON] et al. [40]. In their study, the researchers used a robot called \"Robovie\" in order to perform and test three different behaviours:  
* Robovie approached all the participants without distinction or preliminary estimation in the field test. * It then waited for the participants to start the interaction. * Finally, it decided autonomously whether or not to approach the user based on the intention estimation of the interaction with the participants. The findings showed that the participants enjoyed the third stage the most, i.e., when the interaction from the robot was both \"passive\" and \"proactive\". According to the participants, the robot's behaviour was perceived as more \"natural\" and likeable in the mixed behaviour stage since it had anthropomorphic features. Similarly, [PERSON] et al. [41] analyzed the behavioural implications between the same robot, Robovie, and the acceptance rate of the participants. Prior to analyzing the behavioural aspects, human-human interaction was observed and interviews have been performed in order to categorize three poignant behaviours:  
* Gaze only,
* Precise pointing,
* Casual pointing. After a preliminary stage of manual observations, a model for autonomously generating acceptable pointing behaviour was developed to be tested with the participants. This model allowed the robot to autonomously interact with humans by adopting one of the three proposed behaviours, according to the data obtained from the speech recognition and the user tracking system. The findings of this study highlight the general positive response from the participants who interacted with the robot, although some users pointed out difficulties in understanding the robot's interaction while it was pointing. A significant analysis and discussion on the subject of behavioural interaction in HRI was presented by [PERSON] et al. [42]. In their study, they present a long-term social interaction between a social robot, [PERSON] the receptionist, and the occupants of the research facility at the Carnegie Mellon University.