Patent ID: 7271880

Claim:
An object recognition apparatus for a vehicle, comprising: a radar working to emit a plurality of radar waves over an angular range defined in front of a vehicle equipped with the object recognition apparatus, said radar receiving returns of the radar waves reflected by an object to produce receive signals as functions of intensities of the returns of the radar waves; a time measuring circuit working to measure times required by respective radar waves to travel to and return from the object; an intensity determining circuit working to determining the intensities of the returns of the respective radar waves using the receive signals; an object recognition circuit working to recognize the object based on the radar waves emitted by said radar and the returns received by said radar; and a dirt detecting circuit working to detect adhesion of dirt to said radar, said dirt detecting circuit determining that the dirt is adhered to said radar when a first condition is met, wherein the first condition is when a number of the respective radar waves is greater than or equal to a first value, the respective radar waves having times shorter than a predetermined period of time and having intensities of the returns greater than a predetermined value, the times being measured by said time measuring circuit, the returns being determined by said intensity determining circuit, wherein when said number of the respective radar waves decreases below a second value smaller than the first value after a determination is made that the dirt is adhered to said radar, said dirt detecting circuit cancels the determination that the dirt is adhered to said radar.