@techreport{oai:ipsj.ixsq.nii.ac.jp:00218186, author = {Thilina, Dissanayake and 前川, 卓也 and 原, 隆浩 and Thilina, Dissanayake}, issue = {7}, month = {May}, note = {The number of accidents due to the pedestrians walking on the sidewalk while viewing their smartphones has been increasing in recent years. To prevent such accidents, obstacle detection systems that employ sensor data from smartphones have been developed. The most common method is to employ the video stream from the back camera of the smartphone to recognize the oncoming obstacles. However, this method imposes problems such as poor recognition accuracy during nighttime as well as complications in sensing range due to the holding orientation of the smartphone. To address these issues, methods based on acoustic ranging have been extensively researched in the ubiquitous computing research community. However, the previous studies concentrate on detecting the distance to the oncoming obstacles and often overlook the most important attribute, their velocity relative to the user. In this study, we propose a method to predict both the distance from the user to the obstacle as well as its relative velocity., The number of accidents due to the pedestrians walking on the sidewalk while viewing their smartphones has been increasing in recent years. To prevent such accidents, obstacle detection systems that employ sensor data from smartphones have been developed. The most common method is to employ the video stream from the back camera of the smartphone to recognize the oncoming obstacles. However, this method imposes problems such as poor recognition accuracy during nighttime as well as complications in sensing range due to the holding orientation of the smartphone. To address these issues, methods based on acoustic ranging have been extensively researched in the ubiquitous computing research community. However, the previous studies concentrate on detecting the distance to the oncoming obstacles and often overlook the most important attribute, their velocity relative to the user. In this study, we propose a method to predict both the distance from the user to the obstacle as well as its relative velocity.}, title = {Preliminary Investigation of Predicting the Distance and the Relative Velocirty of the Obstacles via Smartphone Active Sound Sensing for Pedestrian Safety}, year = {2022} }