Theory of Ground Vehicles, 5th Edition

7Vehicle Ride Characteristics

Ride quality is concerned with the sensation or feel of the passenger in the environment of a moving vehicle. Ride comfort issues mainly arise from vibrations of the vehicle body, which may be induced by a variety of sources, including surface irregularities, aerodynamic forces, vibrations of the engine and driveline, and non‐uniformities (imbalances) of the tire/wheel assembly. Usually, surface irregularities, ranging from potholes to random variations of the surface elevation profile, act as a major source that excites the vibration of the vehicle body through the tire/wheel assembly and the suspension system. Excitations by aerodynamic forces are applied directly to the vehicle body, while those due to engine and driveline vibrations are transmitted through engine/transmission mounts. Excitations resulting from mass imbalances and dimensional and stiffness variations of the tire/wheel assembly are transmitted to the vehicle body through the suspension.

The objective of the study of vehicle ride is to provide guiding principles for the control of the vibration of the vehicle body so that the passenger’s sensation of discomfort does not exceed a certain level. To achieve this objective, it is essential to have a basic understanding of the human response to vibration, the vibrational behavior of the vehicle, and the characteristics of surface irregularities.

7.1 Human Response to Vibration

In general, passenger ride comfort (or discomfort) boundaries ...