To detect the change of a road surface state accurately by a device for judging the road surface state.
The side slip angle of a car body is estimated at every assuming road surface state by giving each tyre characteristic and a detected state amount to a vehicle operation model. The side slip angle of the car body at every assuming road surface state estimated at present is corrected based on the present state amount and the side slip angle of the car body before one estimate time. The said processing is carried out by modeling calculation units 10, 12. In a differentiation calculation units 14, 16, the side slip angular velocity of the car body at every assuming road state is calculated as an estimation value based on the side slip angle of the car body at every assuming road surface state after correction. While, in the calculation unit 18, the side slip angular velocity of the car body is calculated as the detection value based on the detected state amount. The present road surface state is judged by the comparison of the detection value with the estimation value at every assuming road surface state.
ASANO KATSUHIRO
TOUTSU KENJI
ITO TAKAYUKI
AISIN SEIKI