RESEARCHES

Smart Vision & and Sensing

Professor, Robotics Laboratory
Department of System Cybernetics, Graduate School of Advanced Science and Engineering
Hiroshima University
Idaku ISHII
>> Research Contents
In order to establish high-speed robot senses that are much faster than human senses, we are conducting research and development of information systems and devices that can achieve real-time image processing at 1000 frames/s or greater. As well as integrated algorithms to accelerate sensor information processing, we are also studying new sensing methodologies based on vibration and flow dynamics; they are too fast for humans to sense.

Real-Time Vocal-Cord Vibration Analysis Using an HFR Laryngoscope

We have developed a high-frame-rate laryngoscope that can measure the vibration distribution of a vocal fold in real time at hundreds of hertz. Our laryngoscope can extract a vocal-fold contour at 4000fps as 20 pairs of its left and right border points from 256×512 images to quantify left-right asymmetry of vocal-fold vibrations in real time.

HFR laryngoscope Our laryngoscope consists of an IDP Express high-speed vision platform and a rigid-type endoscope. The camera head of the IDP Express was mounted at the end of the rigid-type laryngoscope LY-CS30 (Machida Endoscope Ltd.). A contour-extraction algorithm was implemented for 256×512 images at 4000fps on the IDP Express to obtain a velocity distribution as 20 pairs of border points on the left and right edges of a vocal fold in real time. Based on the vibration velocities on the left and right edges of a vocal fold, anamplitude ratio A and correlation ratio R are introduced as quantification indexes for left-right asymmetry of vocal-fold vibrations to indicate the degree of laryngeal diseases.

algorithm

algorithm We examined the vocal-fold vibrations of five human subjects under clinical conditions (512×512 images at 2000fps). Subjects A, B, and C were healthy males in their twenties. Subject D was a female patient in her fifties with a polypous vocal cord, and subject E was a male patient in his thirties who had had a vocal-cord noduleremoved by an operation. For subjects A, B, and C, the amplitude ratios were around 0 and the correlation ratios were around -1. These tendencies indicate that their vocal folds vibrated almost left-right symmetrically. For subject D, it can be observed that the left-right symmetry in the vocal-fold vibrations was strongly disrupted because a polyp on the right side of the vocal fold disturbed vocal-fold vibrations. For subject E, the vocal-fold vibrations were observed to be almost left-right symmetric, but the correlation ratios were slightly less than those of the healthy subjects. This tendency corresponds to the fact that subject E felt an incompatibility in mucous-membrane movement around the site of the nodule removed from the left vocal-fold.

vocal-fold vibration WMV movie(0.3M)
vocal-fold vibrations (five subjects)