Relation Between Seated Person Vibrations and the International Roughness Index

Abstract

Vertical vehicle feet/floor interface vibrations are typically not used to indirectly estimate road roughness. The relation for vehicle floor vibrations, the International Roughness Index (IRI), vehicle speed, and road roughness vertical displacement spectrum according to the ISO 8608: 2016 standard was previously derived only for the simulation of a reference quarter-car model. It was estimated using the in situ measurement of vibrations of a person sitting in a passenger car for different vehicle and road categories, vehicle speed, and road roughness. Vibrations at the feet/floor interface and seat surface of a seated passenger were evaluated with the frequency-weighted root-mean-square vertical acceleration according to the ISO 2631-1: 1997 standard. The results indicated that the simulated results for the quarter-car model may have substantially underestimated the ratio between the vehicle floor vibrations of a seated person and the IRI, but they were similar to seat surface vibrations.