A study of roadside passive reflectors for improvement in the radar reliability on curves and at intersections

Abstract

The use of radar in automotive applications such as adaptive cruise control is limited to detecting target vehicles directly in front of the host vehicle. Vehicles around a curve on a highway and cross-traffic vehicles at an intersection cannot be detected by current radar systems. This is primarily due to the limited beam width angle of the radar. This paper examines and evaluates the novel concept of using passive roadside reflectors (PRRs) to increase the utility of the radar system. PRRs on the shoulder and the median of a road are designed which would enable the radar system to pick up cross traffic at highway intersections. Both simulations and experiments demonstrate that this concept could be effectively used for cross-traffic distance measurement. A limitation of this technology is that cross traffic cannot be detected when the radar-equipped vehicle is close to the intersection, owing to the lateral offset of the radar from the location of the PRR. However, the system is still valuable for providing future warning of cross traffic at rural intersections. A number of options are explored for the use of PRRs to improve radar measurements on highway curves. These include the use of tangential flat-plate reflectors, skewed flat-plate reflectors, and convex reflectors. Algorithms for distance measurement with each of these options are derived and evaluated through simulations. The use of skewed flat-plate reflectors is also evaluated experimentally and found to work effectively. The effective range of the radar on highway curves could be doubled by the use of the developed system.