Abstract
An adaptive cruise control (ACC) system has been developed by using an electronically controlled vacuum booster for smooth brake control and millimeter-wave radar that operates effectively even in rainy weather. The headway control unit was designed based on an analysis of driving behaviour characteristics and achieves natural vehicle behaviour that does not seem strange to drivers. This paper presents an outline of the system along with the results of simulations and driving tests. The effectiveness of the system was evaluated with a driving simulator and in vehicle tests, and the results verified that it reduces the driver's workload. (A)