ISO/TS 21476:2018 PDF

Overview

ISO/TS 21476:2018 - Road vehicles: Displacement calibration method of IR-TRACC devices - defines a standardized procedure to calibrate IR‑TRACC displacement transducers used on crash test dummies. The technical specification covers calibration performed with the sensor disassembled from the dummy and is applicable to both analogue and digital outputs. It addresses the non‑linear measurement physics of IR‑TRACC (infra‑red telescoping rod) sensors and provides repeatable methods for producing calibrated displacement output used in chest‑deflection injury assessment.

Key topics

• Scope & applicability
  • Calibration of IR‑TRACC displacement transducers for road vehicle crash testing.
  • Valid for analogue voltage and digital (LSB) outputs.
• Calibration fixture and setup
  • Requirements for a displacement calibration fixture with fixed and movable heads, rotation freedom, and a displacement gauge resolution of at least 0.01 mm.
  • Axis parallelism guidance (typical maximum deviation ~1.5 mm).
• Measurement & tests
  • Establishing a zero (starting) point near the extended sensor range and defining the calibration range.
  • Tubes In‑Out Calibration Method: records extremes with telescope tubes pushed IN and OUT to account for tube position sensitivity.
  • Forced Lateral Manipulation Test: applies a lateral force of 4.45 N ± 0.15 N at mid‑span in four 90° directions to verify sensitivity to bending.
• Data processing & linearization
  • Linearization of exponential IR phototransistor output (theoretical exponent −0.5), standard nominal exponent used historically (−0.42857) and methods for optimized linearization exponent via numerical optimization.
  • Calculation of calibration factor, sensitivity, intercepts, linearity errors, tubes in‑out variation and pass/fail criteria.
• Documentation
  • Templates and example data are included (annexes) to standardize reporting.

Applications

• Use by crash test laboratories, anthropomorphic test device (ATD) manufacturers, sensor suppliers and calibration service providers.
• Ensures consistent chest compression (displacement) measurements across test facilities for:
  • Regulatory and certification crash tests
  • Product development and safety research
  • Inter‑laboratory comparison and traceable sensor calibration

Related standards

• ISO 6487 - Measurement techniques in impact tests - Instrumentation (referenced for measurement techniques)
• ISO MME coding for displacement (IR‑TRACC outputs are associated with the ISO MME Code DS)

Keywords: ISO/TS 21476:2018, IR‑TRACC, displacement calibration, crash test dummies, linearization exponent, tubes-in/out, forced lateral manipulation, road vehicle instrumentation.