ISO 17288-2:2011

Overview

ISO 17288-2:2011 - Passenger cars - Free-steer behaviour - Part 2: Steering-pulse open-loop test method specifies a repeatable laboratory/test-track procedure to quantify a passenger car’s free-control stability. The method measures transient vehicle response after a single steering-pulse input applied from steady, straight-ahead running. Results characterize how the vehicle returns to a straight path (oscillation, damping and settling) and provide objective metrics for vehicle dynamics and handling assessment.

Key technical topics and requirements

• Test principle: Apply a single steering-wheel pulse, immediately release the wheel and record the vehicle’s free response (open-loop). The steering wheel is then free and the vehicle dynamics determine the response.
• Measured variables: longitudinal velocity (v), lateral acceleration (aY), yaw velocity (ψ), and steering‑wheel angle (δ).
• Measuring equipment & accuracy: Multi-channel recording with suitable transducers. Typical recommended maximum errors include:
  • longitudinal velocity ±0.3 m/s
  • lateral acceleration ±0.1 m/s²
  • yaw velocity ±0.3°/s
  • steering-wheel angle ±2° for |δ| ≤ 180° (±4° otherwise)
• Test conditions & execution: Tests at a minimum of three longitudinal velocities (including the standard 100 km/h and ±20 km/h steps). Initial steering amplitude targets an initial lateral acceleration of 1 m/s², increased in ≤0.5 m/s² steps up to at least 5 m/s². Pulse rise time is specified (0.20 s ± 0.05 s); data recording windows and warm-up requirements follow ISO 15037-1.
• Data analysis: Compute damping (logarithmic-decrement style) and damping time of yaw velocity from successive peak amplitudes, evaluate peak‑2/peak‑1 ratios when oscillation is weak, perform linear regressions over specified lateral-acceleration ranges, and derive summary metrics (q and m) as a function of velocity and initial lateral acceleration.

Practical applications and users

Who benefits:

• Automotive test engineers and vehicle dynamics teams (OEMs and suppliers)
• Independent test laboratories and validation facilities
• R&D groups developing steering systems, chassis tuning, and stability control algorithms
• Researchers comparing vehicle models and validating simulation tools

Typical uses:

• Objective comparison of handling and free-steer stability between vehicle variants
• Development and validation of steering hardware (inertia, friction) and software (ESC calibration)
• Regression testing during prototype iterations and production-change assessments
• Correlating physical tests with simulation models for vehicle dynamics

Note: ISO 17288-2 defines a deliberately non‑typical, open-loop manoeuvre for controlled measurement; its results are one part of a broader handling evaluation. Application for regulation requires demonstrated correlation with real-world safety outcomes.

Related standards

• ISO 3833 - Road vehicles - Types - Terms and definitions
• ISO 8855 - Road vehicles - Vehicle dynamics and road‑holding ability - Vocabulary
• ISO 15037-1:2006 - Road vehicles - Vehicle dynamics test methods - General conditions for passenger cars

Keywords: ISO 17288-2:2011, free‑steer behaviour, steering‑pulse open‑loop test method, passenger cars, vehicle dynamics, yaw velocity, lateral acceleration, steering‑wheel angle, damping, handling test.