Recent progress in vehicle stability and controllability during straight running at high speed realized a small compact car as well as a low energy consumption. The design of these performances requires the consideration of taking the human drivers sensitivity into account. As for the vehicle stability at high speed, the characteristic of detectable yaw-motion is one of the important evaluational properties.

In this study, the human sensitivity for yaw-motion and the threshold characteristics for the change in amplitude are examined using an electric shaker with 6 degrees of freedom to clarify the human sensitivity for rotational sensation.

According to the experimental results, 1) Human sensitivity for yaw-motion is recognizable for low frequency regions below 0.1Hz, and moreover,
2) Even for these low frequency regions, human sensitivity for the detecting abilities of the amplitude changes are evident and the threshold values obeyed Weber's law.

From these facts based on experimental data, the evaluation of stability and controllability of a vehicle is more understandable by taking the human response characteristics into account.