Tracking Motion Direction and Distance With Pyroelectric IR Sensors

TLDR

Passive infrared sensors are low‑cost, low‑power, and compact, widely used for presence detection, but their output is influenced by distance, movement direction, and multiple occupants. The study introduces a feature‑extraction and sensor‑fusion method using multiple PIR‑equipped nodes to track people in a hallway. The method extracts features from PIR signals and fuses data across nodes to determine motion direction and distance. The approach reduces computational and memory demands and achieves 100 % direction detection accuracy and 83.5–95.4 % accuracy for distance intervals.

Abstract

Passive IR (PIR) sensors are excellent devices for wireless sensor networks (WSN), being low-cost, low-power, and presenting a small form factor. PIR sensors are widely used as a simple, but reliable, presence trigger for alarms, and automatic lighting systems. However, the output of a PIR sensor depends on several aspects beyond simple people presence, as, e.g., distance of the body from the sensor, direction of movement, and presence of multiple people. In this paper, we present a feature extraction and sensor fusion technique that exploits a set of wireless nodes equipped with PIR sensors to track people moving in a hallway. Our approach has reduced computational and memory requirements, thus it is well suited for digital systems with limited resources, such as those available in sensor nodes. Using the proposed techniques, we were able to achieve 100% correct detection of direction of movement and 83.49%-95.35% correct detection of distance intervals.