ISO 24227:2023

Overview

ISO 24227:2023 specifies a standard validation and reporting protocol for measuring walking speed extracted from various sensor systems that capture human body motion in the healthcare sector. The standard defines how to compare walking speed from technological sensor systems (e.g., wearable accelerometers, depth sensors, GPS-based systems) with the reference method - walking speed measured using a tape measure and a stopwatch - and sets out study, measurement and reporting requirements to enable consistent accuracy assessment.

Key topics and requirements

• Validation study design
  • Simultaneous measurement by the sensor system and the reference method for each trial.
  • Minimum of 50 data points covering the full walking-speed range of the target population (or equivalent repeated trials).
  • Walkway length guidance (practical minimum about 10 m) with ~3 m acceleration/deceleration zones so steady-speed intervals are recorded.
• Measurer qualifications
  • Measurers should be trained under clinical supervision and by sensor-system representatives. Preferably the same measurer for all trials; report inter-rater reliability if multiple measurers are used (e.g., intraclass correlation).
• Instrumentation and calibration
  • Stopwatch and tape measure must be traceable with an individually serial-numbered calibration certificate meeting ISO/IEC 17025 requirements.
• Data analysis and metrics
  • Compute per-trial difference (d) between sensor and reference speeds, root-mean-square error (RMSE), 95% confidence interval of the mean, and measurement bias.
  • Provide Bland–Altman plots to characterise bias and limits of agreement.
• Reporting
  • Use the provided Annex A template and sample report (Annex B). Required items include participant demographics, tested speed range, environment, sensor type/location, hardware/software versions, mean/SDs, RMSE, 95% CI, and Bland–Altman results.

Applications and who uses it

• Manufacturers of wearable and environment-embedded motion sensors use ISO 24227:2023 to validate and demonstrate walking-speed accuracy against the clinical reference method.
• Clinical researchers and rehabilitation clinicians use the protocol to evaluate sensor performance before deploying systems for patient monitoring or trials.
• Ergonomists and occupational health professionals who need validated walking-speed data for workplace assessments and fatigue indices.
• Regulators and procurement teams can rely on standardized validation reports when comparing systems.

Keywords: ISO 24227:2023, walking speed validation, sensor systems, healthcare, reference method, RMSE, Bland–Altman, accelerometer, GPS, depth sensor, validation protocol.

Related standards

• ISO/IEC 17025 (calibration laboratory competence) - referenced for traceable tape-measure calibration.