Human Sensing Using Visible Light Communication

Abstract

We present LiSense, the first-of-its-kind system that enables both data communication and fine-grained, real-time human skeleton reconstruction using Visible Light Communication (VLC). LiSense uses shadows created by the human body from blocked light and reconstructs 3D human skeleton postures in real time. We overcome two key challenges to realize shadow-based human sensing. First, multiple lights on the ceiling lead to diminished and complex shadow patterns on the floor. We design light beacons enabled by VLC to separate light rays from different light sources and recover the shadow pattern cast by each individual light. Second, we design an efficient inference algorithm to reconstruct user postures using 2D shadow information with a limited resolution collected by photodiodes embedded in the floor. We build a 3 m × 3 m LiSense testbed using off-the-shelf LEDs and photodiodes. Experiments show that LiSense reconstructs the 3D user skeleton at 60 Hz in real time with 10 • mean angular error for five body joints.

Battery-free Visible Light Sensing

“…VLC requires retrofitting of the luminaries with specialized driving circuits [6][7][8] to modulate Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than ACM must be honored.…”

“…Modifying existing lighting infrastructure significantly increases the cost and complexity of deployment [14]. Further, existing VLC systems use complex reception logic and circuitry to perform demodulation [6], or FFT operations [7,8] which further hinders pervasive deployment of VLS systems. Thus, a key enabler to achieve widespread deployment of VLS systems is to use unmodulated ambient light for sensing.…”

“…Recent efforts show that sensing changes in the cast shadow enables human sensing capability [7,8], or tracking of hand gestures [3]. However, several limitations remain that hinder widespread deployment: First, some prior shadow sensing systems use modulated light [7,8] which, as discussed above, makes the deployment complex. Second, these systems [3,7,8] employ conventional light sensing mechanisms.…”

“…However, several limitations remain that hinder widespread deployment: First, some prior shadow sensing systems use modulated light [7,8] which, as discussed above, makes the deployment complex. Second, these systems [3,7,8] employ conventional light sensing mechanisms.…”

“…Conventional light sensing mechanisms [3,7,8] employ sensors with components that negatively affect pervasive deployment: they amplify the signals from photodiodes using transimpedance amplifiers (TIA), sample using analog to digital converters (ADCs), and process using computational blocks involving microcontrollers (MCUs) or field-programmable gate arrays (FPGAs). Further, the events are communicated using traditional RF radios [1] or external cables [7,8].…”