Expressive Robot Motion Timing

TL;DR

This paper explores how robot motion timing can be designed to express internal states and intentions, enabling more transparent human-robot interactions through systematic investigation and modeling.

Contribution

It introduces a systematic study of expressive motion timing, identifying key properties users interpret, and develops models for optimizing timing to convey internal states.

Findings

Users interpret timing cues related to confidence, naturalness, and object weight.

Mathematical models strongly correlate with user perceptions.

Robots can use these models to autonomously generate expressive motion timing.

Abstract

Our goal is to enable robots to \emph{time} their motion in a way that is purposefully expressive of their internal states, making them more transparent to people. We start by investigating what types of states motion timing is capable of expressing, focusing on robot manipulation and keeping the path constant while systematically varying the timing. We find that users naturally pick up on certain properties of the robot (like confidence), of the motion (like naturalness), or of the task (like the weight of the object that the robot is carrying). We then conduct a hypothesis-driven experiment to tease out the directions and magnitudes of these effects, and use our findings to develop candidate mathematical models for how users make these inferences from the timing. We find a strong correlation between the models and real user data, suggesting that robots can leverage these models to autonomously optimize the timing of their motion to be expressive.