Passenger cars -- Free-steer behaviour
ISO 17288-1:2011 specifies an open-loop test method for determining the free control stability of a passenger car as defined in ISO 3833, by measurement of the transient behaviour following steering release, starting from a steady-state cornering status.
Voitures particulières -- Comportement volant libre
Standards Content (sample)
Passenger cars — Free-steer
Steering-release open-loop test method
Voitures particulières — Comportement volant libre —
Partie 1: Méthode d'essai en boucle ouverte avec relâchement du
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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 part of ISO 17288 may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 17288-1 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 9, Vehicledynamics and road-holding ability.
This second edition cancels and replaces the first edition (ISO 17288-1:2002), of which it constitutes a minorrevision.
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
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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 interactions 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 differenttests.
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 dynamicbehaviour.
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 purposeswill require proven correlation between test results and accident statistics.
iv © ISO 2011 – All rights reserved
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INTERNATIONAL STANDARD ISO 17288-1:2011(E)
Passenger cars — Free-steer behaviour —
Steering-release open-loop test method
This part of ISO 17288 specifies an open-loop test method for determining the free control stability of a
passenger car as defined in ISO 3833, by measurement of the transient behaviour following steering release,starting from a steady-state cornering status.
NOTE The open-loop manoeuvre specified in this part of ISO 17288 is not representative of normal driving
conditions, but is nonetheless 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 referenceddocument (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 forpassenger 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 for evaluating the ability of a vehicle to return to a straight path following steering-wheelrelease from a steady-state turn.
The initial conditions are defined by a steady-state circular motion. During the test, the driver releases the
steering wheel. The steering-wheel angle and the vehicle response are measured and recorded. From therecorded signals, characteristic values are calculated.
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5.1 Reference system
The provisions given in ISO 15037-1:2006, 3.1, apply.
Measure the following variables (see ISO 8855):
⎯ longitudinal velocity (v );
⎯ lateral acceleration (a );
⎯ yaw velocity (ψ );
⎯ steering-wheel angle (δ ).
6 Measuring e