Ride quality investigation of seat with an active control system to minimize vertical vibrations from seat to human body in a vehicle (3rd report, in the case of an occupant-seat-vehicle system)

Abstract

This paper describes a vibration reduction system that can minimize the vertical vibrations of the human body in a vehicle. This system can control the mechanical properties of the seat cushions and seat back cushions, such as the spring constants and damping coefficients. In previous study, it was estimated a vibration model considering vibrations transmitted from the bottom of the seat and the footrest, and vibration reduction effects of the human body was examined by using this model. However, vibrations transmitted from vehicle body have a frequency characteristic affected by the sprung mass, unsprung mass and engine. Therefore, it is necessary to investigate vibration reduction effects by a model including vehicle system. The purpose of this paper is to clarify the vibration reduction effects for the driver by controlling mechanical properties of the seat. In this study, we design a vibration model of an occupant-seat-vehicle system and a numerical analysis system, and examine the feasibility of the vibration reduction system based on the vibration model of the occupant-seat-vehicle system. Further, a numerical analysis with an optimized algorithm is carried out to calculate the magnitude of vibrations transmitted to the human body. The feasibilities of both the vibration model and numerical analysis system were confirmed by comparing the results of the occupant-seat system between the numerical analysis and the measurement. The vibration reduction system successfully reduced vibrations from the seat to the human body by the analytical results using ISO 8608:1995. In addition, analytical results clearly show differences of the vibration reduction between the model with the steering wheel and the model without the steering wheel.