We used Cozmo robots in this experiment: https://anki.com/en-us/cozmo.html
Short demo video: https://youtu.be/bQ8_tBvg5dI
Long demo video: https://youtu.be/00YXN0hwKX4
Paper: http://ro-man2020.unina.it/full-papers.php
@inproceedings{zhou2020would,
title={Would you help a sad robot? Influence of robots' emotional expressions on human-multi-robot collaboration},
author={Zhou, Shujie and Leimin, Tian},
booktitle={2020 29th IEEE International Conference on Robot and Human Interactive Communication (RO-MAN)},
year={2020},
organization={IEEE}
}