Gait Analysis as a Fall Risk Biomarker
Research shows gait speed below 0.8 m/s is a strong fall risk predictor in elderly people. Scientists call walking speed the sixth vital sign because it simultaneously reflects neurological, musculoskeletal, and balance health. Changes in gait can be detected 6–12 months before a fall occurs.
Gait Analysis Technologies for the Home
Pressure Mat Array (Floor Pressure Sensor): lay a pressure-sensitive mat 3–6 metres along the main walking path. Measures foot pressure distribution on every step — capturing step length, step width, cadence, and left-right pressure asymmetry.
VelSi Pressure Mat (commercial): a 16×16 pressure sensor grid priced at 15,000–50,000 THB — detailed data but expensive for consumer use.
DIY Pressure Mat: FSR (Force Sensitive Resistor) array with Arduino/ESP32 reading raw ADC values and publishing via MQTT — cost 2,000–5,000 THB. Zone-level data only, but adequate for detecting step patterns.
Optical Flow Camera (privacy-safe): ceiling-mounted camera looking down. OpenCV optical flow analysis computes the speed of the person’s centre of mass — no face recorded, only velocity vectors. Privacy-preserving.
Depth Camera (Intel RealSense D435): depth map enables 3D joint position tracking (skeleton tracking) for the most detailed gait parameters — cost 8,000–15,000 THB.
Gait Parameters and Thresholds
Gait speed: normal for elderly 0.8–1.2 m/s. Below 0.8 m/s = moderate risk. Below 0.6 m/s = high fall risk — inform a doctor.
Step length: normal 50–70cm (men), 45–60cm (women). Drop >20% from baseline within 1 month → yellow alert.
Cadence (steps/min): normal 100–120. Drop below 80 steps/min may indicate pain or muscle weakness.
Step width (base of support): increase above 30cm indicates balance compensation for worsening stability.
Double support time (both feet on ground simultaneously): increase >30% of gait cycle → high fall risk.
Digital TUG Test (Timed Up and Go)
Standard TUG: sit in chair, stand, walk 3 metres, return and sit. Normal <12 seconds; 12–20 seconds = moderate risk; >20 seconds = high risk.
Digital TUG in Home Assistant: pressure mat or camera detects when the person rises from the chair (chair has a pressure sensor) and stops the timer when they sit again. HA logs the time and tracks a weekly trend. If TUG time increases >20% from baseline, the family is alerted.
Home Assistant Gait Monitoring Automation
A Python script running at 20:00 daily processes that day’s gait data, calculates a Daily Gait Score, and compares it to the 30-day rolling average. If the score falls below threshold, a weekly LINE OA summary is sent: Gait Speed x.x m/s (trend ↑↓), TUG x.x seconds, Fall Risk: 🟢/🟡/🔴.
ROI and Fall-Related Healthcare Cost Reduction
Hip fracture treatment costs for elderly Thai patients: 150,000–500,000 THB. Gait monitoring system cost: 5,000–20,000 THB one-time. Preventing even a single fall returns the investment many times over.