Abstract
This study employs a novel 3D engineered robotic eye system with dielectric elastomer actuator (DEA) pupils and a 3D sculpted and colourised gelatin iris membrane to replicate the appearance and materiality of the human eye. A camera system for facial expression analysis (FEA) was installed in the left eye, and a photo-resistor for measuring light frequencies in the right. Unlike previous prototypes, this configuration permits the robotic eyes to respond to both light and emotion proximal to a human eye. A series of experiments were undertaken using a pupil tracking headset to monitor test subjects when observing positive and negative video stimuli. A second test measured pupil dilation ranges to high and low light frequencies using a high-powered artificial light. This data was converted into a series of algorithms for servomotor triangulation to control the photosensitive and emotive pupil dilation sequences. The robotic eyes were evaluated against the pupillometric data and video feeds of the human eyes to determine operational accuracy. Finally, the dilating robotic eye system was installed in a realistic humanoid robot (RHR) and comparatively evaluated in a human-robot interaction (HRI) experiment. The results of this study show that the robotic eyes can emulate the average pupil reflex of the human eye under typical light conditions and to positive and negative emotive stimuli. However, the results of the HRI experiment indicate that replicating natural eye contact behaviour was more significant than emulating pupil dilation.
Highlights
This practical study follows on from two previously published position papers on the application of dilating robotic pupils in human-robot interaction (HRI) [1,2]
Pupil size and dynamics are important components of eye contact interfacing during human communication as they act as subconscious visual cues of emotional state and attention [4,5]
Previous robotic eye prototypes with dilating pupils are incapable of responding to both light and emotion, which is not indicative of the sensory capabilities of the human eye [1]. This consideration is significant per the Uncanny Valley (UV) hypothesis, which suggests that realistic humanoid robot (RHR) fall into the UV as they lack organic nuances such as pupil dilation and accurate lip-sync
Summary
This practical study follows on from two previously published position papers on the application of dilating robotic pupils in HRI [1,2]. Pupil dilation alone is not an accurate representation of an emotional state as the effect is synergistic, incorporating other facial features such as eyebrows, mouth and cheeks to display recognisable human emotions [6] This condition is significant in HRI as engineers continually neglect dynamic pupils in robotic eyes, which make RHRs eyes look cold and lifeless [7,8]. Previous robotic eye prototypes with dilating pupils are incapable of responding to both light and emotion, which is not indicative of the sensory capabilities of the human eye [1] This consideration is significant per the Uncanny Valley (UV) hypothesis, which suggests that RHRs fall into the UV as they lack organic nuances such as pupil dilation and accurate lip-sync. The code, video footage and CAD materials for this project are available in the GitHub repository in the supplementary materials section
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