Effect of linear and angular accelerations of head on equilibrium sense in vehicle braking motion

In this paper, the relation between vehicle motion and passenger's sensation is examined as an example of deceleration movement while braking. A newly designed experimental setup is composed of a seat with fixed casters and a rail whose direction is variable in the sagittal plane. The motions of a subject's head on equilibrium sense were measured in low deceleration range of about 3m/s². When driving, drivers can take a stance against the inertia force that acts on them due to the vehicle motion because they anticipate the inertia force from their maneuvers while accelerating, steering, and braking. On the other hand, passenger's action is generally not related to the maneuver of the vehicle. In this paper, we examine the effect of deceleration movement on the passenger in order to reduce the influence of the anticipating behavior by the driver. We observed the head acceleration and obtained a hint for designing the vehicle motion. We found that the pitching motion by the driving of the front-side of the seat reduces the linear acceleration on head; therefore, can help improve passenger's ride comfort while braking.