Abstract: The quantity description method of human thinking fuzziness is introduced in the evaluation index of handling and stability of driver/vehicle/road closed-loop system. The ftizzy cognition of driver on prediction distance is firstly introduced in the evaluation index of driver/vehic!e/road closed-loop system. Then, the objective analysis and reasoning are conducted, Finally, the possibility distributed set and its three explicit expressions of the fuzzy evaluation on handling and stability of driver/vchicle/road closed-loop system are given. The optimization and simulation experiment are conducted on the basis of (he theoretical analysis. The results show that the upper and lower bounds of fuzzy possibility distribution interval of the lateral displacement response are distinct as the confident level on fuzzy set "long prediction distance" is of larger. And the tracking performance of fuzzy possibility distribution interval of the lateral displacement response to desired path is good. The upper and lower bounds of fuzzy possibility distribution interval of the lateral displacement response have a cross point as the confident level on fuzzy set "long prediction distance" is of smaller. And the tracking performance of the upper bound of fuzzy possibility distribution interval of the lateral displacement response to desired path is good. The tracking performance of lower bound of fuzzy possibility distribution interval of the lateral displacement response to desired path is bad. The contribution of this study is that the effect of subject factor to object evaluation index is developed, and the mathematical description of the effect is given.

Key words: Driver/vehicle/road Handling stability Fuzzy evaluation Simulation