Ultrasonic scanning, imaging and recognition of bottles

A compact machine has been developed to take in returnable bottles. Using ultrasonics, it recognizes up to 150 different bottles. A teaching facility allows store personnel to add new types of bottles to the reference set. The ultrasonic system operates in air and employs a strongly focussing parabolic acoustical mirror in combination with a linear array of three transducers to image the bottle. To reduce artifact, phase-insensitive detection is incorporated. Automatic calibration helps to achieve the relatively high accuracy required. Dedicated recognition software attempts to match the present bottle to one in the reference set. The ultrasonic system and recognition software are discussed. >