Human response to buffeting in an all-terrain vehicle.

Suitably prepared subjects were exposed to the vibration imposed by driving a personal-type all-terrain vehicle over a heavily plowed track. Acceleration was measured in the Z-axis at the seat of the vehicle, and in the X, Y, and Z axes at the hip and head of the subjects. Acceleration peaks, rates of onset, durations, and frequency ranges were determined and a spectral analysis conducted. Results showed that, for this vehicle under the test circumstances, the subjects respond with a low-frequency (less than 4 Hz) oscillation at approximately 0.5 Gz above nominal, on which are imposed numerous peaks of 1 to 5 G, or higher with rates of onset within the range measured, of 20 to 100 G/s. Although the measurement system did not conform to ISO (International Standards Organization) requirements, the results suggest that continued exposure would exceed the ISO 1-min limit for "health and safety."