CapLoc: Capacitive Sensing Floor for Device-Free Localization and Fall Detection

Abstract

Passive indoor positioning, also known as Device-Free Localization (DFL), has applications such as occupancy sensing, human-computer interaction, fall detection, and many other location-based services in smart buildings. Vision-, infrared-, wireless-based DFL solutions have been widely explored in recent years. They are characterized by respective strengths and weaknesses in terms of the desired accuracy, feasibility in various real-world scenarios, etc. Passive positioning by tracking the footsteps on the floor has been put forward as one of the promising options. This article introduces CapLoc, a floor-based DFL solution that can localize a subject in real-time using capacitive sensing. Experimental results with three individuals walking 39 paths on the CapLoc show that it can detect and localize a single target's footsteps accurately with a median localization error of 0.026 m. The potential for fall detection is also shown with the outlines of various poses of the subject lying upon the floor.

Device-Free Localization Using Privacy-Preserving Infrared Signatures Acquired From Thermopiles and Machine Learning

“…For this reason, the HTC Vive 3 was used as the ground truth tool. In previous works, it was found to be accurate to within several mm for extended time periods [15,36]. The "tracking puck" needs to be kept within the line of sight of the "lighthouses".…”

“…The devised parametric model utilizes an approach similar to the thermopile positioning [23] and capacitive floor footprints detection reported in [15]. After the temperature data are preprocessed (as described above in Section II D), it is reshaped to an 8×8 frame.…”

“…Various alternative sensing techniques, based on the use of the Radio Frequency (RF) Received Signal Strength Indicator [8], Wi-Fi Channel State Information [9], visible light [10,11], and electric field [12,13] were proposed for DFL. Localization using pressure-sensitive [14] and capacitive [15] floors were also investigated. There were reports on techniques that applied single-pixel cameras [16], ultrasonic [17], and acoustic [18] sensing.…”

Working Principle and Performance of a Scalable Gravimetric System for the Monitoring of Access to Public Places

“…A different field of application for smart floors, footboards and platforms is security [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ]. Herein, the floor is used to monitor the occupancy of surveilled or sensitive areas, possibly to identify the people present inside these areas and, finally, in the novel application field considered in this paper, for the control of access in walk-through gates.…”

“…Regarding this, slim and flexible sensor matrices, that can be embedded into the floor with no encumbrance for human activities, represent one of the latest research fields. Different sensor types are employed: the more common and recent proposals, that can be found in the literature, involve capacitive sensors [ 16 ] and piezoresistive Polymer Thick Films (PTFs) [ 8 , 9 , 10 , 11 , 14 ]. A more advanced piezoresistive carbon nanotube polymer sensor matrix is presented in [ 20 ].…”