The Six Hug Commandments: Design and Evaluation of a Human-Sized Hugging Robot with Visual and Haptic Perception

TL;DR

Adding haptic reactivity definitively improves user perception a hugging robot, largely verifying four new tenets of natural and enjoyable robotic hugging and illuminating several interesting opportunities for further improvement.

Abstract

Receiving a hug is one of the best ways to feel socially supported, and the lack of social touch can have severe negative effects on an individual's well-being. Based on previous research both within and outside of HRI, we propose six tenets ("commandments") of natural and enjoyable robotic hugging: a hugging robot should be soft, be warm, be human sized, visually perceive its user, adjust its embrace to the user's size and position, and reliably release when the user wants to end the hug. Prior work validated the first two tenets, and the final four are new. We followed all six tenets to create a new robotic platform, HuggieBot 2.0, that has a soft, warm, inflated body (HuggieChest) and uses visual and haptic sensing to deliver closed-loop hugging. We first verified the outward appeal of this platform in comparison to the previous PR2-based HuggieBot 1.0 via an online video-watching study involving 117 users. We then conducted an in-person experiment in which 32 users each exchanged eight hugs with HuggieBot 2.0, experiencing all combinations of visual hug initiation, haptic sizing, and haptic releasing. The results show that adding haptic reactivity definitively improves user perception a hugging robot, largely verifying our four new tenets and illuminating several interesting opportunities for further improvement.

Figures (6)

• Figure 1: A user hugging HuggieBot 2.0.
• Figure 2: The inflated HuggieChest when lying flat. The two air chambers form the front and back of the robot's torso.
• Figure 3: The responses to the five questions asked after users watched two videos of people hugging HuggieBot 2.0 (HB2) and HuggieBot 1.0 (HB1).
• Figure 4: The breakdown of preferences when users had two choices (top) and four choices (bottom), with the associated images. The colors of the second plot show which robot the user preferred in the first selection round.
• Figure 5: A comparison of the responses to the opening (blue) and closing (red) surveys. The top and bottom of the box represent the 25th and 75th percentile responses, respectively, while the line in the center represents the median, and the triangle indicates the mean. The lines extending past the boxes show the farthest data points not considered outliers. The + marks indicate outliers. The black lines with stars at the top of the graph indicate statistically significant differences.