| 摘要 |
In an object sensing member M 1, while electromagnetic waves are transmitted from transmission members 1 and 2 to a predetermined region, based upon a result of receiving electromagnetic waves reflected from an object by reception members 3 and 4, a distance detecting member 5 detects at least a distance of the object. An abnormal condition judging member M 2 judges that the object sensing member M 1 is under abnormal condition, if a difference between a maximum value of reception levels of the electromagnetic waves received by the reception members 3 and 4, and a minimum value of these reception levels for a predetermined time measured by a time measuring member M 3 is smaller than a predetermined threshold value. As a result, the abnormal condition judging member M 2 can surely judge the abnormal condition even, if the vehicle is driven on a desert road where objects to be sensed are occasionally present. |
