Abstract
Although various research to improve vehicle driving stability has been performed, it has not been sufficiently explained what information from the multiple types of movement that occur during driving is used by vehicle occupants when evaluating driving stability. Moreover, various devices for vehicle dynamics control have been developed recently, making it more and more possible to control the character of vehicle dynamics freely. Methods of vehicle dynamics control based on these developments have begun to be proposed. However, the details of what vehicle dynamics characteristics should be targeted to create a comfortable driving experience for occupants have yet to be clarified. In order to find a solution for these issues, it is important to understand the occupants´ visual and motion sensitivity to vehicle behavior. Therefore, the first step of this study involved the development of human sensitivity evaluation system.
Developed evaluation system is composed of a highly responsive six-degree-of-freedom (6-DOF) motion device and a visual device with high spatial frequency resolution. And this system enables the test subject to experience motion as body sensory information and images as visual information to simulate the type of vehicle behavior. The 6-DOF motion device is made up of three five-bar link (parallel link) mechanisms, therefore, this motion device is small, but its working area is larger than that of the Stewart platform. Moreover, for the purpose of achieving high response, the motion base has been simplified to meet minimum requirements to reduce its mass, and each element and joint of the device have been designed to achieve sufficient stiffness. In particular, the shape of the links driven by the AC servo-motors were optimized based on FEM analysis.
The first human sensitivity analysis performed with this system involved the studying of visual sensitivity to single motions. The type of visual sensitivity discussed here are motion recognition and motion discrimination. Motion recognition means the perception of the direction of a movement, and motion discrimination means the perception between different movements. As a result, it was found that (1) rotational motion is recognized and discriminated by the amplitude of angular velocity, and (2) translational motion is recognized and discriminated by the amplitude of velocity.
Keywords:Vehicle dynamics, human sensitivity, evaluation system, perception, experiment.