MOFU: Development of a MOrphing Fluffy Unit with Expansion and Contraction Capabilities and Evaluation of the Animacy of Its Movements

Robots for therapy and social interaction are often intended to evoke "animacy" in humans. While many robots imitate appearance and joint movements, little attention has been given to whole-body expansion-contraction, volume-changing movements observed in living organisms, and their effect on animacy perception. We developed a mobile robot called "MOFU (Morphing Fluffy Unit)," capable of whole-body expansion-contraction with a single motor and covered with a fluffy exterior. MOFU employs a "Jitterbug" structure, a geometric transformation mechanism that enables smooth volume change in diameter from 210 to 280 mm using one actuator. It is also equipped with a differential two-wheel drive mechanism for locomotion. To evaluate the effect of expansion-contraction movements, we conducted an online survey using videos of MOFU's behavior. Participants rated impressions with the Godspeed Questionnaire Series. First, we compared videos of MOFU in a stationary state with and without expansion-contraction and turning, finding that expansion-contraction significantly increased perceived animacy. Second, we hypothesized that presenting two MOFUs would increase animacy compared with a single robot; however, this was not supported, as no significant difference emerged. Exploratory analyses further compared four dual-robot motion conditions. Third, when expansion-contraction was combined with locomotion, animacy ratings were higher than locomotion alone. These results suggest that volume-changing movements such as expansion and contraction enhance perceived animacy in robots and should be considered an important design element in future robot development aimed at shaping human impressions.

Development of the Lifelike Head Unit for a Humanoid Cybernetic Avatar `Yui' and Its Operation Interface

In the context of avatar-mediated communication, it is crucial for the face-to-face interlocutor to sense the operator's presence and emotions via the avatar. Although androids resembling humans have been developed to convey presence through appearance and movement, few studies have prioritized deepening the communication experience for both operator and interlocutor using android robot as an avatar. Addressing this gap, we introduce the ``Cybernetic Avatar `Yui','' featuring a human-like head unit with 28 degrees of freedom, capable of expressing gaze, facial emotions, and speech-related mouth movements. Through an eye-tracking unit in a Head-Mounted Display (HMD) and degrees of freedom on both eyes of Yui, operators can control the avatar's gaze naturally. Additionally, microphones embedded in Yui's ears allow operators to hear surrounding sounds in three dimensions, enabling them to discern the direction of calls based solely on auditory information. An HMD's face-tracking unit synchronizes the avatar's facial movements with those of the operator. This immersive interface, coupled with Yui's human-like appearance, enables real-time emotion transmission and communication, enhancing the sense of presence for both parties. Our experiments demonstrate Yui's facial expression capabilities, and validate the system's efficacy through teleoperation trials, suggesting potential advancements in avatar technology.