ISO 7401:2011 pdf download

The primary object of these tests is to determine the transient response behaviour of a vehicle. Characteristicvalues and functions in the time and frequency domains are considered necessary for characterizing vehicletransient response.

lmportant characteristics in the time domain are:

a) time lags between steering-wheel angle, lateral acceleration and yaw velocity;

b) response times of lateral acceleration and yaw velocity (see 10.2.1 and 10.2.2;
c) lateral acceleration gain (lateral acceleration divided by steering-wheel angle);
d) yaw velocity gain (yaw velocity divided by steering-wheel angle); and

e)overshoot values (see 10.2.3).

These characteristics show correlation with subjective evaluation during road driving.

lmportant characteristics in the frequency domain are the frequency responses, i.e. amplitudes and phases of:

—lateral acceleration related to steering-wheel angle; and

-yaw velocity related to steering-wheel angle.

5.2 Test methods

There are several test methods for obtaining these characteristics in the domains of time and frequency, theapplicability of which depends in part on the size of the test track available.

a) Time domain:

1) step input; and

2 sinusoidal input (one period).b)Frequency domain:

1) random input;
2) pulse input; and

3) continuous sinusoidal input.

These test methods are optional, but at least one of each domain type should be performed.The methodschosen shall be indicated in the general data specified in Annex A and in the presentation of test resultsspecified in Annex B.