An attempt to measure the vibration of the occupant of the vehicle seat with the non-contact measurement method

Abstract

In our previous study, we aimed at achieving human-adaptive vibration design in a vehicle cabin on the basis of the passengers’ sensory characteristics. To this end, the passengers’ psychological stress caused by seat and floor vibration in a commercial vehicle was analyzed. However, we measured the vibrational acceleration of each occupant by employing a vibrational acceleration sensor directly attached to the occupant’s body. Hence, there is a possibility that attaching the sensor to the occupants’ bodies induced psychological stress. Based on this rationale, in this study, we measured the vibrational acceleration of an occupant’s body without attaching a sensor by incorporating a non-contact measurement method. We employed a laser displacement sensor for measuring the vibrational acceleration of the occupant’s body because such a sensor has higher temporal and spatial resolutions. We simultaneously measured the displacement of the occupant’s body and the corresponding vibrational acceleration of the laser displacement sensor. Subsequently, we estimated the vibrational acceleration of the occupant’s body by incorporating the difference between the second derivative of the measured displacement with respect to time and vibrational acceleration of the sensor. The obtained results indicate that within a low-frequency range, the estimated vibrational acceleration of the occupant’s body is nearby identical in value to that of the previous vibrational acceleration sensor, which was directly attached to the occupant’s body.