Wide-Range Sensor Network System by Limited Sensors Based on Various Image Analysis Method

With the spread of ICT technology, it has become common for people to spend long hours at their desks in the office, which hurts their health. In addition, this effect leads to stress, which in turn reduces concentration and makes it difficult to produce good results at work. Consequently, it is necessary to observe regular stress and encourage breaks to prevent prolonged sitting at the desk. To solve this problem, sensing systems have been researched and developed to measure heartbeats by mounting sensors on desk chairs and user interfaces of the computer and to analyze the measurement results. The existing methods require many sensors to be installed on various devices and thus cause large costs. On the other hand, the existing methods measure heartbeats without contacting the device. For example, existing research has constructed a fatigue estimation system using a non-contact Doppler sensor that can measure heartbeats and breathing from a distance. However, existing Doppler sensors are directional, meaning that they can only observe a specific direction, making it impossible to observe a large number of people at the same time with only a limited number of sensors. Therefore, in this study, we combine an omnidirectional camera and a Doppler sensor to develop a system that analyzes and records the stress values of each individual by estimating the position of each individual from the images captured by the camera and adjusting the orientation of the Doppler sensor in that direction. In the proposed system, by combining an omnidirectional directional camera and a directional sensor, a large number of people can be placed in the observation range with a small number of sensors.