ISO 17288-2:2011

Passenger cars - Free-steer behaviour - Part 2: Steering-pulse open-loop test method

ISO 17288-2:2011 specifies a procedure for determining the free control stability of a passenger car as defined in ISO 3833, by measurement of the transient behaviour following steering pulse input, starting from a straight-ahead, steady-state status.

Voitures particulières — Comportement volant libre — Partie 2: Méthode d'essai en boucle ouverte avec impulsion au volant

General Information

• Status: Published
• Publication Date: 15-Feb-2011
• ICS: 43.100 - Passenger cars. Caravans and light trailers
• Technical Committee: ISO/TC 22/SC 33 - Vehicle dynamics and chassis components
• Drafting Committee: ISO/TC 22/SC 33/WG 2 - Vehicle dynamics of passenger cars
• Current Stage: 9093 - International Standard confirmed
• Start Date: 16-Aug-2023
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 17288-2:2004 - Passenger cars - Free-steer behaviour - Part 2: Steering-pulse open-loop test method
• Effective Date: 04-Feb-2009

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.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 17288-2
Second edition
2011-02-15
Passenger cars — Free-steer
behaviour —
Part 2:
Steering-pulse open-loop test method
Voitures particulières — Comportement volant libre —
Partie 2: Méthode d'essai en boucle ouverte avec impulsion au volant

Reference number
©
ISO 2011
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ii © ISO 2011 – All rights reserved

Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 Normative references.1
3 Terms and definitions .1
4 Principle.1
5 Variables.2
6 Measuring equipment.2
7 Test conditions .3
8 Test procedure.3
9 Data analysis.4
Bibliography.13

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 17288-2 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 9, Vehicle
dynamics and road-holding ability.
This second edition cancels and replaces the first edition (ISO 17288-2:2004), of which it constitutes a minor
revision.
ISO 17288 consists of the following parts, under the general title Passenger cars — Free-steer behaviour :
⎯ Part 1: Steering-release open-loop test method
⎯ Part 2: Steering-pulse open-loop test method
iv © ISO 2011 – All rights reserved

Introduction
The main purpose of this part of ISO 17288 is to provide repeatable and discriminatory test results.
The dynamic behaviour of a road vehicle is a very important aspect of active vehicle safety. Any given vehicle,
together with its driver and the prevailing environment, constitutes a closed-loop system that is unique. The
task of evaluating the dynamic behaviour is therefore very difficult since the significant interaction of these
driver-vehicle-environment elements are each complex in themselves. A complete and accurate description of
the behaviour of the road vehicle must necessarily involve information obtained from a number of different
tests.
Since this test method quantifies only one small part of the complete vehicle handling characteristics, the
results of these tests can only be considered significant for a correspondingly small part of the overall dynamic
behaviour.
Moreover, insufficient knowledge is available concerning the relationship between overall vehicle dynamic
properties and accident avoidance. A substantial amount of work is necessary to acquire sufficient and
reliable data on the correlation between accident avoidance and vehicle dynamic properties in general and the
results of these tests in particular. Consequently, any application of this test method for regulation purposes
will require proven correlation between test results and accident statistics.
INTERNATIONAL STANDARD ISO 17288-2:2011(E)

Passenger cars — Free-steer behaviour —
Part 2:
Steering-pulse open-loop test method
1 Scope
This part of ISO 17288 specifies a procedure for determining the free control stability of a passenger car as
defined in ISO 3833, by measurement of the transient behaviour following steering pulse input, starting from a
straight-ahead, steady-state status.
NOTE The open loop manoeuvre specified in this part of ISO 17288 is not representative of normal driving
conditions, but is useful for obtaining a measure of vehicle transient behaviour.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
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 — Part 1: General conditions for
passenger cars
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 3833 and ISO 8855 apply.
4 Principle
This test is intended to evaluate the ability of the vehicle to return to a straight path following a steering pulse
input from a straight-ahead, steady-state driving initial condition.
Oscillation of the vehicle is initiated by the application of a single pulse steering input. This is followed by
release of the steering wheel and a period during which the steering wheel is free. The steering-wheel angle
and the vehicle response are measured and recorded. From the recorded signals, characteristic values are
calculated.
5 Variables
5.1 Reference system
The provisions given in ISO 15037-1:2006, 3.1, apply.
5.2 Measurement
Measure the following variables (see ISO 8855):
a) longitudinal velocity (v );
X
b) lateral acceleration (a );
Y

c) yaw velocity ()ψ ;
d) steering-wheel angle (δ ).
H
6 Measuring equipment
6.1 Description
All variables shall be measured by means of appropriate transducers, and their time histories shall be
recorded by a multi-channel recording system. Typical operating ranges, and recommended maximum errors
of the transducer and recording system, are given in Table 1.
Table 1 — Variables, their typical operating ranges and recommended maximum errors
Recommended maximum error
Variable Typical operating range of the combined transducer
and recorder system
Longitudinal velocity 0 m/s to +50 m/s ±0,3 m/s
2 2 2
Lateral acceleration
−15 m/s to +15 m/s ±0,1 m/s
Yaw velocity
−50°/s to +50°/s ±0,3°/s
±2° for |δ | u 180°
H
Steering-wheel angle −360° to +360°
±4° otherwise
Transducers for measuring some of the listed variables are not widely available and not in general use. Many
such instruments are developed by users. If any system error exceeds the recommended maximum value,
this and the actual maximum error shall be stated in the test report given
...