Human tracking and identification using a sensitive floor and wearable accelerometers

Abstract

We describe a method for user tracking and localization based on textile capacitive sensor arrays placed under the floor. The sensor array is a commercial product (SensFloor R ) that can be installed under any standard floor type (from carpet to stone) and is able to detect objects (including the user's foot) being placed on it. The challenges addressed in this paper are (1) how to map sequences of such signals onto user trajectories and (2) how to correlate the steps detected by the SensFloor system with the step detection based on a wearable accelerometer as means of user identification. Footstep detection is performed online on the devices, which are seamlessly integrated with the floor's wireless sensor network. Initial experiments performed over a week in a real life office environment show the ability to track multiple humans and to identify up to three users walking in a narrow corridor at the same time.

Finding Common Ground

“…For example, in many capacitive indoor localization systems, a significant amount of instrumentation is needed underneath the floor [15,194,205]. Reusing parts of the environmental infrastructure for active sensing seems promising.…”

“…Active sensing approaches for indoor localization commonly involve embedding large loading mode electrodes underneath floor tiles to determine on which tile the user is standing [15,57,194]. Alternatively, the entire floor can act as a single transmit electrode using transmit mode.…”

“…IMUs have also been used to correlate whole-body movements to capacitive sensing data [109,194] and avoid accidental interactions [107]. Other work has combined acoustic sensors [16], cameras [48] and resistive sensors [112,140,145] with capacitive approaches.…”

Multi-scale Conditional Random Fields for first-person activity recognition on elders and disabled patients

“…This suggests that preferable parts to mount the accelerometers are in the main body, such as pelvis [12], chest [13] or head [14]. Recently, such techniques have been integrated into mobile phones [15][16][17], or deployed with additional sensors to improve accuracy, such as gyroscopes [18], microphones [19], and floor sensors [20].…”

Capacitive near-field communication for ubiquitous interaction and perception

“…In the domain of proximity sensing, capacitive coupling can be used for recognizing gestures [14,28], sensing user locations [29] or their activities [13,37]. Also, capacitive sensing was used in wearable devices to measure muscle contractions for activity recognition [4].…”