Influence of Vection-Induced Images on Autonomic Regulation Evaluated by Time-Varying Behavior of Motion Vectors 木竜 徹 新潟大学大学院自然科学研究科 Tohru Kiryu Graduate School of Science and Technology, Niigata University Abstract — Virtual reality (VR) is promising technology, but at the same enlarges another problem called cybersickness. Aiming at suppression of cybersicknes, we are investigating the influences of vection-induced images on autonomic regulations quantitatively. Using estimated motion vectors, we further synthesized random-dot pattern images as contents-free images. In a test by synthesized images, we surveyed which component of the global motion vector seriously affected the autonomic regulation. The results showed that the zoom component would induce sickness and under unpleasant situation the time-frequency representation of motion vectors revealed the switching behavior of a dominant vibration frequency that was related to camera work. We finally demonstrated the system function approach by the multivariable ARX model and successfully correlated the global motion vectors and the low-frequency power of blood pressure. As a result, the system function approach will benefit to predict the levels of cybersickness for individuals. Keywords — cybersickness, autonomic regulation, motion vector, vection, multivariable ARX model
Approaches １． Database of Biosignals affected by Vection-Induced Images : � 映像生体影 � の出現が確認されている映像に対し， 生体信号でみられた特徴のデータベース化 ２． Featuring the Components of Image by Motion Vectors : 動きベクトルによる映像要素の特徴づけ ３． Analysis by Synthesized Images : � 映像要素を様々に変 えたシミュレーション映像を制作し，映像生体影 � を � 析 ４． Estimation of System Function by Multivariate ARX Model : � 映像の動きベクトルを入力とし、自律神経系の概周期 的な生体信号（心拍変動や呼吸波形、 � 圧波形など）を出力と する多変量 ARX モデル推定 Influence of Vection-Induced Images on Autonomic Regulation Evaluated by Time-Varying Behavior of Motion Vectors ， MEB Symposium 2003 ， September 5, 2003
Rating of Image （映像のレイティング） Strength of Unpleasant Impression under Vection-Induced Images = ( prediction - required level for images ) targets for evaluation ( experience for image contents ) ¥ ( brightness, frame size, and frame rate etc. ) ¥ Hierarchy of Image Components prediction Motion Vector scene scenario brightness color frame rate visual characteristics filtering Specification of Display Influence of Vection-Induced Images on Autonomic Regulation Evaluated by Time-Varying Behavior of Motion Vectors ， MEB Symposium 2003 ， September 5, 2003
Several Time-Scales in Biosignals 前庭感 � 系 Motivation for Exercise Vestibular System Visual System Brain 視 � 系 Somatic Sensors 自律神経系 Motor Command Autonomic Nervous System Neuromuscular system for Continuing Physical Activity for Controlling Exercise Muscles Energy Metabolism for Continuing Exercise Proprioception short long time-scale Influence of Vection-Induced Images on Autonomic Regulation Evaluated by Time-Varying Behavior of Motion Vectors ， MEB Symposium 2003 ， September 5, 2003
Rating of Personal Features （個人性のレイティング） 感 � 系の不調和 Discrepancy between visual and vestibular systems sensory conflict theory - prediction-required level for images 予測レベル - experience for image contents 経験レベル targets for evaluation Influences appearing on autonomic regulations Disturbance for Autonomic Regulations 自律神経系への影 � Influence of Vection-Induced Images on Autonomic Regulation Evaluated by Time-Varying Behavior of Motion Vectors ， MEB Symposium 2003 ， September 5, 2003
Study Overview viewing biosignal biosignal extraction extraction motion vector motion vector real image real image synthesis synthesis biosignal biosignal viewing random-dot image by CG random-dot image by CG Influence of Vection-Induced Images on Autonomic Regulation Evaluated by Time-Varying Behavior of Motion Vectors ， MEB Symposium 2003 ， September 5, 2003
Quantization of Image by Motion Vector Local Motion Vector Global Motion Vector Local Motion Vector Global Motion Vector Local Motion Vector Global Motion Vector pan zoom distant view camera tilt motion of camera motion of camera local motion in a screen local motion in a screen Post frame y Current frame y tilt bottom up approach 秦泉寺久美ら,“スプライト生成のためのグローバルモーション x 算出法と符号化への適用” ， � 子情報通信学会和文論文誌D-II， J83-D-II, 2: 535-544, 2000. x block matching method Influence of Vection-Induced Images on Autonomic Regulation Evaluated by Time-Varying Behavior of Motion Vectors ， MEB Symposium 2003 ， September 5, 2003
Signal Processing Biosignals Biosignals image image Blood Vection-induced Image Respiration ECG Pressure Extraction Extraction Local Motion Vector averaged BP averaging RR interval ( LMV ) Time-Frequency Time-Frequency Global Motion Vector Analysis Analysis ( GMV ) Autonomic Nervous Activity Related Indices Time-Frequency Time-Frequency Low frequency ( 0.03 ~ 0.15 Hz ) Analysis Analysis Mayer Wave Mayer Wave Substantial Features of Image High frequency (0.16 – 0.45 Hz ) Respiration Respiration Influence of Vection-Induced Images on Autonomic Regulation Evaluated by Time-Varying Behavior of Motion Vectors ， MEB Symposium 2003 ， September 5, 2003
Experiments under Real Images real images subjects real images subjects - 1st Experiment : Five healthy elderly subjects - 1st Experiment : Five healthy elderly subjects Parachute (from 52 to 71 yrs. old) and six elderly subjects with (from 52 to 71 yrs. old) and six elderly subjects with mild hypertension or diabetes mellitus (5 males and 1 Bobsleigh mild hypertension or diabetes mellitus (5 males and 1 female from 50 to 71 yrs. old) . female from 50 to 71 yrs. old) . boat boat - 2nd Experiment : ten healthy young subjects (8 - 2nd Experiment : ten healthy young subjects (8 Go cart males and two female from 21 to 24 yrs. old) males and two female from 21 to 24 yrs. old) Hang glider Measured Biosignals Biosignals Measured Mountain-bike Mountain-bike ECG : chest ECG : chest Car race Car race Respiration : tube sensors around the chest Bungee jump Respiration : tube sensors around the chest and the abdomen diving diving and the abdomen Blood Pressure : tonometry method Blood Pressure : tonometry method Bike race Bike race Blood flow : Laser Doppler at thumb sphere of Blood flow : Laser Doppler at thumb sphere of Vehicle left hand left hand experiencing video Perspiration : Capsule type sensor at thumb Perspiration : Capsule type sensor at thumb sphere of left hand sphere of left hand at Niigata University （ Nov. 13, 14, 1999, Jan. 19, 21, Mar. 17, 2000 ） Influence of Vection-Induced Images on Autonomic Regulation Evaluated by Time-Varying Behavior of Motion Vectors ， MEB Symposium 2003 ， September 5, 2003
Searching Candidates from Components of Motion Vectors （動きベクトルの要素を探る） Subjects Subjects Experimental Protocol … T1 T6 S R S T2 S R S Ten healthy young subjects (8 males Ten healthy young subjects (8 males and 2 female from 21 to 24 yrs. old) and 2 female from 21 to 24 yrs. old) 3 min 3 min 2 min 1 min S : still picture T : test under conditioned image R : rest contents random-dot pattern synthesized by CG random-dot pattern synthesized by CG based on motion vectors from real mountain bike image a b c Comparison between Comparison between T1 1 ． ． GMV and LMV GMV and LMV 1 T2 Synthesized ． among GMV parameters 2 ． among GMV parameters 2 only by motion T3 vector ． among LMV parameters 3 ． 3 among LMV parameters T4 a : zoom 4 ． ． among frequencies 4 among frequencies T5 b : pan 5 ． ． among frequencies for among frequencies for 5 T6 c : tilt switching switching at Niigata University on Dec. 1-22, 2002. Influence of Vection-Induced Images on Autonomic Regulation Evaluated by Time-Varying Behavior of Motion Vectors ， MEB Symposium 2003 ， September 5, 2003
ARX Model with Time Delay input-output w.n. Components of Motion Vectors Autonomic Nervous Activity 1 Related Index A zoom B Mayer wave pan A related signal tilt time sequence time sequence of output order of n a time sequence of input order of n b na nb y ( t )= S a i y ( t - i ) + S b j u ( t - j-n d ) + e ( t ) delay order of n d i =1 j =1 Influence of Vection-Induced Images on Autonomic Regulation Evaluated by Time-Varying Behavior of Motion Vectors ， MEB Symposium 2003 ， September 5, 2003
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