What you reward is what you learn: Comparing rewards for online speech policy optimization in public HRI

Fuente: arXiv
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Auteurs principaux: Song, Sichao, Okafuji, Yuki, Ariu, Kaito, Koike, Amy
Format: Preprint
Publié: 2026
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author Song, Sichao
Okafuji, Yuki
Ariu, Kaito
Koike, Amy
author_facet Song, Sichao
Okafuji, Yuki
Ariu, Kaito
Koike, Amy
contents Designing policies that are both efficient and acceptable for conversational service robots in open and diverse environments is non-trivial. Unlike fixed, hand-tuned parameters, online learning can adapt to non-stationary conditions. In this paper, we study how to adapt a social robot's speech policy in the wild. During a 12-day in-situ deployment with over 1,400 public encounters, we cast online policy optimization as a multi-armed bandit problem and use Thompson sampling to select among six actions defined by speech rate (slow/normal/fast) and verbosity (concise/detailed). We compare three complementary binary rewards--Ru (user rating), Rc (conversation closure), and Rt (>=2 turns)--and show that each induces distinct arm distributions and interaction behaviors. We complement the online results with offline evaluations that analyze contextual factors (e.g., crowd level, group size) using video-annotated data. Taken together, we distill ready-to-use design lessons for deploying online optimization of speech policies in real public HRI settings.
format Preprint
id arxiv_https___arxiv_org_abs_2601_01969
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle What you reward is what you learn: Comparing rewards for online speech policy optimization in public HRI
Song, Sichao
Okafuji, Yuki
Ariu, Kaito
Koike, Amy
Robotics
Designing policies that are both efficient and acceptable for conversational service robots in open and diverse environments is non-trivial. Unlike fixed, hand-tuned parameters, online learning can adapt to non-stationary conditions. In this paper, we study how to adapt a social robot's speech policy in the wild. During a 12-day in-situ deployment with over 1,400 public encounters, we cast online policy optimization as a multi-armed bandit problem and use Thompson sampling to select among six actions defined by speech rate (slow/normal/fast) and verbosity (concise/detailed). We compare three complementary binary rewards--Ru (user rating), Rc (conversation closure), and Rt (>=2 turns)--and show that each induces distinct arm distributions and interaction behaviors. We complement the online results with offline evaluations that analyze contextual factors (e.g., crowd level, group size) using video-annotated data. Taken together, we distill ready-to-use design lessons for deploying online optimization of speech policies in real public HRI settings.
title What you reward is what you learn: Comparing rewards for online speech policy optimization in public HRI
topic Robotics
url https://arxiv.org/abs/2601.01969