Automatic Curve Deceleration System Using Enhanced ACC with Navigation System 2008-01-0922

We have developed a system for automatic deceleration upon entering curves to prevent collisions on tight curves on high-ways. The navigation system is used to determine safe speed negotiating the curve, defined as a speed that will keep lateral acceleration within a settled value. The navigation system sends the curve radius to a controller, which calculates the safe speed for the curve. The controller then sends the speed command to the ACC system, which adjusts the vehicle speed. One of the important features in this system is the estimation of the vehicle position, in terms of its distance from the curve entrance. Navigation systems have a certain amount of dispersion in positional accuracy. A front camera is used in our system to decrease this dispersion. This camera detects lane markers (white lines, raised pavement markers, etc.) using our line recognition technologies¹⁾. The change in the curve radius is detected by the lateral displacement of the markers to estimate the position of the curve entrance. The proposed technique in this estimation is to use a transient curve model. The lateral displacement of the markers changes according to the clothoid function in the curve entrance. By curve-fitting the data from the lateral displacement of the markers, which was obtained by the front camera, and by comparing the data with the clothoid function, the precise position of the curve entrance can be estimated. The developed system has been installed in a prototype vehicle. Safe deceleration upon entering curves has been demonstrated successfully. The demonstration video will be shown in the presentation.