Patent ID: 8633832

Claim:
A method of detecting an obstacle present on a road on which a vehicle travels, said vehicle having an electromagnetic wave transceiver that transmits an electromagnetic wave in a course of travel of the vehicle and receives reflection waves reflected from at least one reflection object successively, comprising the steps of: successively scanning a plurality of first detection regions, said first detection regions being vertically adjacent one another and disposed generally parallel to a surface of the road; determining whether a high reflection wave, whose reflection level exceeds a high detection threshold value, exists in the received reflection waves in any one of said plurality of first detection regions reflected from one of said at least one reflection object; when said high reflection wave is determined to exist in said any one of said plurality of first detection regions such that said high reflection wave can be associated with a first of said at least one reflection object, further determining whether a low reflection wave, whose reflection level exceeds a low detection threshold value set lower than the high detection threshold value, exists in another of the received reflection waves in other of the first detection regions that is different from the any one of said first detection regions in which the first high reflection object is determined to exist, and when said low reflection wave is determined to exist, setting the reflection object corresponding to the low reflection wave as the obstacle; and when the high reflection wave is determined to exist in any one of said first detection regions and said low reflection wave is not found to exist in in the received reflection waves in said plurality of first detection regions, comprising the further steps of: increasing the low detection threshold value and operating the transceiver to scan second detection regions successively, the second detection regions being laterally adjacent one another and disposed generally perpendicular to the surface of the road; and determining whether the low reflection wave reflected from a second reflection object exists in any waves reflected from the second detection regions, and upon determining the existence of low reflection waves corresponding to the second reflection object, determining the second reflection object as the obstacle.