| 摘要 |
PROBLEM TO BE SOLVED: To provide a two-dimensional position detector for vehicles, capable of detecting the two-dimensional position of a vehicle from an obstacle. SOLUTION: A control unit 5 actuates two piezoelectric elements 11, 12 of each ultrasonic wave sensor 1-4 one after the other for only a fixed time to radiate an ultrasonic wave and receive its reflected ultrasonic wave, thereby obtaining the calculated position of an obstacle, based on the time difference between them. The piezoelectric elements 11, 12 are mounted and oriented in directions different 90 deg. and hence only the distances can be detected from input/output signals of the piezoelectric elements but the position can be obtd. as an intersection point of concentric circles with the radii of the distances.
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