Characteristics of Displacement Behavior of Dummy Skin Using Convergent Ultrasonic Haptic Actuators.

Haptics is a research field related to the sense of touch. When humans perceive vibrations, the magnitude of sensory quantity is determined by the amount of skin displacement. A haptic actuator using mid-air ultrasonic waves is suitable for measuring the skin displacement during tactile presentation because they allow contactless tactile presentation. However, studies that directly observe the amount of skin displacement during the sensing of vibration have been conducted only at a very limited displacement of 3 µm, despite the sensible skin displacement range being approximately 10 mm-0.01 µm. In this study, ultrasonic speakers were used to generate higher sound pressures than conventional ultrasonic speakers to produce large displacements. The goals of this study are to observe the characteristics of skin displacement and to map the amount of displacement to the sensory amount. In this paper, we used a dummy skin instead of a biological skin to investigate the validity of the constructed observation system and the adaptability of the skin viscoelasticity model proposed in the previous study. From the measurement results, obtained at a maximum acoustic radiation pressure of 4000 Pa, a maximum displacement of 170 µm is obtained. This is 50 times larger than that obtained in the previous study. The displacement amount is consistent with the displacement model proposed in the previous study and the elastic modulus obtained from the dynamic viscoelasticity measurement. Furthermore, the simulation results obtained from that model suggest that the displacement characteristics of Asker C15 of HITOHADA® GEL would be similar, suggesting that this HITOHADA® GEL could be used as an alternative material. [ABSTRACT FROM AUTHOR]