Paper 5: The Correlation between Subjective Assessments and Physical Measurements of the Vibratory Motion in a Saloon Car

Panels of observers travelled short distances in three vehicles, which were identical except for suspension components. The motion experienced by the observers was varied by alterations to tyre pressures, spring rates, dampers, and types of road surface, and was measured by accelerometers and a gyro feeding a magnetictape recorder or a galvo-recorder.

Good correlation was found between subjective assessments and simplified data obtained from detailed frequency analyses of the recorded motions of the vehicles. It is shown that the average vertical acceleration passed by a 0·75-6-c/s filter as measured by an accelerometer placed between a passenger and his seat is a good measurement of how subjects react to the low-frequency ride of a vehicle. Higher frequency floor motions, measured as the average acceleration passed by a 7-50-c/s filter, also showed good correlation with subjective assessments. The average angular displacement in pitch passed by a 0·75-6-c/s filter showed some relationship with subjective assessments of pitching of the vehicles, but roll was seldom commented on by the subjects.

The simplified measurements of linear and angular motions in two relatively wide frequency bands yield useful ride quality data; the information can be obtained by the use of relatively simple and inexpensive equipment.