Sensing Ultrasonic Mid-Air Haptics with a Biomimetic Tactile Fingertip

Noor Alakhawand,Kipp Mcadam Freud,Nathan F Lepora,William Frier,Orestis Georgiou

doi:10.1007/978-3-030-58147-3_40

Noor Alakhawand, Kipp Mcadam Freud + Show 3 more

Open Access

https://doi.org/10.1007/978-3-030-58147-3_40

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Abstract

AbstractUltrasonic phased arrays are used to generate mid-air haptic feedback, allowing users to feel sensations in mid-air. In this work, we present a method for testing mid-air haptics with a biomimetic tactile sensor that is inspired by the human fingertip. Our experiments with point, line, and circular test stimuli provide insights on how the acoustic radiation pressure produced by the ultrasonic array deforms the skin-like material of the sensor. This allows us to produce detailed visualizations of the sensations in two-dimensional and three-dimensional space. This approach provides a detailed quantification of mid-air haptic stimuli of use as an investigative tool for improving the performance of haptic displays and for understanding the transduction of mid-air haptics by the human sense of touch.

Highlights

Ultrasonic phased arrays can generate haptic sensations in mid-air
We present a method for analyzing mid-air haptic sensations with a tactile sensor, allowing us to quantitatively test ultrasonic arrays with a method inspired by the human sense of touch
We measured the response of the tactile sensor to a focal point of pressure generated by an ultrasonic haptic array as well as two haptic shapes, each generated by Amplitude Modulation (AM) and Spatiotemporal Modulation (STM)

Summary

Introduction

Ultrasonic phased arrays can generate haptic sensations in mid-air. They focus acoustic radiation pressure in space, which deflects the skin to induce tactile sensation [1]. To evaluate whether the array is producing the desired haptic sensations, we need to understand how focal points of pressure interact with compliant skin to cause it to deform. Efforts to measure the haptic output from a phased ultrasonic array range from quantitative to qualitative. Quantitative methods include microphones to measure the sound pressure level of the generated focal points [1,8], directly measuring the ultrasonic output of the system without considering its interaction with other material. Qualitative methods include pulsed schlieren imaging, which was used to visualize the pressure field produced by a focal point as it interacts with external materials [5]. New research has used a microphone-based tactile sensor array to evaluate the vibrations of its surface due to ultrasonic haptic sensations [9], highlighting the potential of tactile sensors for testing the output of a haptic system

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