Abstract
Abstract. When the fire brigade arrives at a burning building, it is of vital importance that people who are still inside can quickly be found. Smart buildings should be able to expose this location data to the fire brigade working in a smart city. In this paper the feasibility is researched of using ultrasonic sound sensors for human presence detection in smoke-filled spaces. This type of sensor could assist the fire brigade when evacuating a large building by directing them to the places where their help is most needed. The advantage of ultrasonic sound over other sensors or cameras is that its signal is able to pierce through smoke, does not require badges or other wearable devices and introduces little privacy and security risks. In addition, ultrasonic sensors are very inexpensive making it possible to equip every room of a building with an ultrasonic presence detector. In this research both a preliminary ultrasound measuring device and signal processing algorithm have been designed. Testing results show that the walking movement of a person in an indoor area can be detected with the combination of the sensor and the algorithms. In addition, tests of the signal strength in smoke have shown that ultrasound is capable of “looking through” the smoke. The algorithm based on a particle filter allows for more information to be extracted from the relatively simple sensor signal by detecting human walking movement specifically and opens up the way for an ultrasound based indoor positioning system that can be used in emergency situations.
Highlights
In large building fires, an important factor that determines the strategy of the fire brigade is the presence of people inside the building
A continuous ultrasound tone of 41KHz was emitted by the sensor and its echo was recorded with a sampling frequency of 96KHz
The recorded sound was saved as a wav file and processed afterwards using the algorithm described in the Performance of the particle filter in an office
Summary
An important factor that determines the strategy of the fire brigade is the presence of people inside the building. ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume IV-4/W7, 2018 3rd International Conference on Smart Data and Smart Cities, 4–5 October 2018, Delft, The Netherlands istic movement signature in the ultrasonic signal This signature is caused by the separately moving parts of the object and is often called the micro-Doppler signature (Kalgaonkar and Raj, 2007). The frequency of the echo of a walking person changes due to the Doppler effect This happens at all of the separately moving body parts because the moving parts either elongate or compress a sound wave depending on the direction of their movement. Together all the small movements and their associated frequency changes cause a so called Doppler signature in the spectrogram Based on this it is possible to discriminate between types of movement based on the ultrasonic signal.
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