Unobtrusive and ubiquitous in-home monitoring: A methodology for continuous assessment of gait velocity in elders

Stuart Hagler, Daniel Austin, Tamara L. Hayes, Jeffrey Kaye, Misha Pavel

Research output: Contribution to journalArticlepeer-review

131 Scopus citations


Gait velocity has been shown to quantitatively estimate risk of future hospitalization, a predictor of disability, and has been shown to slow prior to cognitive decline. In this paper, we describe a system for continuous and unobtrusive in-home assessment of gait velocity, a critical metric of function. This system is based on estimating walking speed from noisy time and location data collected by a "sensor line" of restricted view passive infrared motion detectors. We demonstrate the validity of our system by comparing with measurements from the commercially available GAITRite walkway system gait mat. We present the data from 882 walks from 27 subjects walking at three different subject-paced speeds (encouraged to walk slowly, normal speed, or fast) in two directions through a sensor line. The experimental results show that the uncalibrated system accuracy (average error) of estimated velocity was 7.1 cm/s (SD $=$ 11.3 cm/s), which improved to 1.1 cm/s (SD $=$ 9.1 cm/s) after a simple calibration procedure. Based on the average measured walking speed of 102 cm/s, our system had an average error of less than 7% without calibration and 1.1% with calibration.

Original languageEnglish (US)
Article number5339193
Pages (from-to)813-820
Number of pages8
JournalIEEE Transactions on Biomedical Engineering
Issue number4
StatePublished - Apr 2010


  • Eldercare
  • Gait
  • Passive infrared (PIR) motion detectors
  • Ubiquitous computing
  • Unobtrusive monitoring
  • Walking speed

ASJC Scopus subject areas

  • Biomedical Engineering


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