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Whole body vibration deals with the biodynamic responses of human body in various postures. Vertical vibration exposure in sitting posture is common situation encountered while driving vehicle or riding motorcycle. We have chosen Wan & Schimmel's 4 DOF biodynamic model for this study by referring the goodness of fit results for various models available in the literature. A single degree of freedom model of motorcycle is used for analysis of whole body vibration on two wheeler. We have neglected pitch, yaw movements of two wheeler for purpose of simplicity. Whole body vibration analysis for human body in sitting posture is described by three terms i.e. Seat to Head Transmissibility (STH), Driving point impendence (DPM) & apparent mass (AP). In order to analyze human response on motorcycle Road to head (RTH), Road to lower torso (RTLT), Road to viscera (RTV), Road to upper torso (RTUT) responses are calculated for different motorcycle suspension natural frequencies.

The three main objectives that a suspension system of an automobile must satisfy are ride comfort, vehicle handling and suspension working space. The aim of this paper is to design and analyze the semi active suspension system models using skyhook, ground hook and hybrid control method. The two degree of freedom (2 DOF) quarter car model is used for analysis of vehicle body displacement, vehicle acceleration and suspension working space and dynamic tire deflection. Simulation of semi active control models are carried out in MATLAB SIMULINK which describes performance of passive system, skyhook on-off and continuous control, ground hook control and hybrid control methods. Time response analysis shows that, for road bump excitation of 70mm vertical displacement, skyhook on-off control improves ride comfort for the results of maximum peak to peak body displacement with 27.53% improvement than that of the passive suspension model.