Foreign-object inspection inside returnable glass bottles

Need

The camera looks through the narrow bottle mouth: the whole base is seen within a small angle and the sidewall darkens the image edge. Water droplets left after washing, the knurled base ring and the base dome also cast shadows; solid objects and pooled residual liquid must be told apart from them.

Solution approach

The base is lit from below with transmitted light: the glass appears bright, anything inside as a dark silhouette. A long-focal-length camera looks straight down the bottle axis and images the base disc the mouth allows. Dark blobs are classified by area and shape: a compact blob is a solid object, a low-contrast ring is residual liquid; knurling and dome are masked.

Process steps

1. 01

   Infeed

   Washed empty bottles arrive at the station in single file.

2. 02

   Transfer

   The trigger photo-sensor sees the bottle; side belts grip it by the body, leaving the base clear above the light.

3. 03

   Acquire

   As the bottle arrives over the light, the base light strobes and the camera images the base through the mouth.

4. 04

   Analyse

   The bright base image is searched for dark blobs; by area and shape they are classified as solid object or residual liquid.

5. 05

   Decide

   Blob area is compared with the threshold; a contaminated bottle is pushed off.