VibroTracker: a Vibrotactile Sensor Tracking Objects
Leo MIYASHITA∗, Yuko ZOU†, Masatoshi ISHIKAWA‡
University of Tokyo

Abstract
Although vibrotactile feedback enlivens virtual interaction, it is difficult to measure actual vibrations of moving objects. Our VibroTracker system achieves this with an optical gaze controller and alaser Doppler vibrometer, enabling users to relive the vibrotactile
sensations experienced by others.

bration velocity. Figure 2 (b), (c) shows that the VibroTracker could
also measure the vibration of the paddle and ball in motion. Thissystem enables spectators to pretend to be a player and enjoy thegames, and even allows them to experience the simulated sensationof touching the ball in motion.

Keywords: tactile sensor, vibrotactile sensation, laser Doppler
vibrometer, haptic media

1Introduction

It is exciting merely to watch sports events, but simulating the haptic sensations experienced by a player would make spectating evenmore enjoyable. This is not peculiar to sports events. In addition
to video and audio, the ability to relive the sensations experienced
by others would also offer great entertainment value at temporaland spatial distances (Fig. 1). One example of such a device isthe TECHTILE toolkit [Minamizawa et al. 2012], which is userfriendly and has expressive power, but existing systems have someproblems in measuring vibrations. A contact-type vibrometer deforms the original vibrations and is a burden to wear or carry. Even
with a non-contact sensor like a microphone, it is difficult to measure slight vibrations of a fast-moving target against the surrounding noise. Our VibroTracker system solved these issues by usinga laser Doppler vibrometer (LDV) and a high-speed optical gazecontroller (Saccade Mirror), enabling users to relive the vibrotactile sensations experienced by others.

2(a) Vibration speaker

Vibrometer and Tracking System

VibroTracker consists of two parts, an LDV and a Saccade Mirror.
The LDV is an optical transducer used for determining the vibration velocity and displacement at an irradiated point [Günther et al.
2009]. The LDV enables vibration measurement with high accuracy, in real time, without any influence from surrounding noise orphysical contact. The Saccade Mirror adjusts a camera’s pan and tilt
angles and can keep an object always at the center of the viewing
field by means of visual feedback [Okumura et al. 2011]. When theLDV is coaxially mounted on the Saccade Mirror, non-contact vibration measurement of a fast-moving target becomes possible. The
object vibrations are reproduced by a vibrator attached to a similar
object held by the user, allowing the user to share the vibrotactile
sensations.

3

Figure 1: Reliving another’s vibrotactile sensations.

Experiments

In an experiment, the VibroTracker measured the vibrations of threetargets at a distance of 3 m using an eye-safe (Class 2) laser: a vibrating speaker radiating a 55 dB, 1 kHz sine wave, a ping-pongpaddle smashing a ball, and a ping-pong ball on the rebound. Fig.
2 (a) shows that vibration measurement and object tracking worked
well when the vibrating speaker was moved manually. The sinewave and motion of the object are shown respectively in the highfrequency component and the low-frequency component of the vi∗ e-mail:LeoMiyashita@ipc.i.u-tokyo.ac.jp
Zou@ipc.i.u-tokyo.ac.jp‡ e-mail:Masatoshi Ishikawa@ipc.i.u-tokyo.ac.jp† e-mail:Yuko(b) Ping-pong paddle smashing a ball.

(c) Ping-pong ball on the rebound.

Figure 2: The vibrations of three targets.

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