Modeling of a Seated Human Body Exposed to Vertical Vibrations in Various Automotive Postures

Abstract

IntroductionIn a seated posture, humans are most sensitive to whole-body vibrations under low-frequency excitation; therefore, biodynamic responses of a seated human body when exposed to vertical vibrations have attracted much attention through the years. Moreover, knowledge of the human responses to vibrations requires an understanding the cause-effect relationships among the transmission of vibrations through the body and its health, comfort and performance. These responses have been widely assessed in terms of seat-to-head (STH) transmissibility, drivingpoint mechanical (DPM) impedance, and apparent (AP) mass. The first function refers to the transmission of motion through the body; whereas the other two pertain to the force and motion at the point of vibration input.The human body is a very sophisticated dynamic system whose mechanical properties vary from one moment to another and from one individual to another. From the results of a large amount of experimental data, various biodynamic models have been developed to describe human motion. According to different techniques, these models can be grouped as lumped-parameter (LP), finiteelement (FE), and multibody (MB) models.An LP model consists of lumped masses, springs and dashpots [1][2][3][4][5][6][7][8][9][10][11][12][13][14] . A variety of experiments have also been implemented by various researchers under widely varying testing conditions, involving vibration excitations, postural constraints, and subject populations. These have, therefore, resulted in significant variations between the different data sets generated. In an effort to define generalized values for characterizing the biodynamic responses of a seated body in the most commonly encountered work environments, Boileau et al.

Whole-body Vibratory Response Study Using a Nonlinear Multi-body Model of Seat-occupant System with Viscoelastic Flexible Polyurethane Foam

“…Despite their advantages, multibody models, especially in more than one dimension, have not been used widely, though there are a few models described in the literature, such as those developed by Nishiyama [5][6][7] Cho and Yoon 8) , Kim et al 9) , Matsumoto and Griffin 10) , Yoshimura et al 11) , Valentini and Vita 12) , Teng et al 13) , and Verver et al 14,15) . The dynamic response of a seated human is affected by a number of conditions, such as hand position 16,17) , pos-ture [17][18][19] , foot support 16,17) , position of the occupant, and most importantly, back support [17][18][19] . The contribution of backrest in the human response to vibration is significant, as observed by Rakheja et al 20) .…”

Evaluation of Vehicular Discomfort Measures Produced by Speed Bumps Using Numerical Simulation

“…The mass, stiffness and damping were based on [10]. The motorcycle suspensions are upside down -type.…”

“…proved that there is a good correlation between the method of analysis and human sensitivity to vibration demonstrated by experimental studies of exposure to all types of vibration, [9,10].…”

Robust Control for Ride Comfort Improvement of an Active Suspension System considering Uncertain Driver's Biodynamics

“…They employed a vertical vibration model of human body together with the plant of the seat suspension system [19]. So far, some human biodynamic models have been proposed by related researchers [20][21][22][23]. Moreover, some of them are standardized in ISO [14].…”