PIR Sensors: Characterization and Novel Localization Technique

Abstract

Pyroelectric Infra-Red (PIR) sensors are used in many applicationsincluding security. PIRs detect the presence ofhumans and animals from the radiation of their body heat.This could be used to trigger events, e.g., opening doors,recording video, etc. PIRs are used widely because of theirlow power consumption.Hitherto, PIR sensors were used for binary event generation– human/animal present or not-present. At the sametime simple binary output hinders the use of PIR sensors ina wide variety of sophisticated applications. In the literature,we find limited characterization of analog output fromPIR sensors that could provide much more information.We built a simple array of PIR sensors and packaged themin a tower. We used two sets of four PIR sensors and tappedtheir analog signals after amplification. Our major contributionis the characterization of analog signals from the PIRsensors. We describe many interesting aspects obtained fromthe analog signals, which have not been explored until now.We also show their correspondence with the range, speedand size of the moving object. Using the characterization ofPIR sensors analog data as well as simple binary decisionsfrom these PIR sensors, we: (i) classify moving object withhigh precision; and (ii) localize the moving object. The majorincentives are low operating power compared to WSNs.We achieve 30 cm accuracy in 80% of the times, whenranging up to 5 m. Over multiple experiments for differentpersons in the range 1-10 m, we show that the error probabilityfor localization is 0.08 at moderate distances (around5-6 m). Our work will help in designing better detectionand application triggers using PIR sensors in the near future.We believe that this work will open up new avenues inthe development of new applications with PIR sensors.