Machine vision reads electricity meters

The Shanghai Power Corporation (Shanghai, China) has undertaken a 5--10-year program to replace old kilowatt/hour meters with more accurate models, but to do so the utility must record and store the final readings from the old meters. In 2005, the utility contracted with Microview Science & Technologies (Beijing, China; www.microview.com) to develop a vision system that images the old meters after they have been packed in cartons.

Feb 5th, 2007

The Shanghai Power Corporation (Shanghai, China) has undertaken a 5--10-year program to replace old kilowatt/hour meters with more accurate models, but to do so the utility must record and store the final readings from hundreds of thousands of the old meters. In 2005, the utility contracted with system-integrator Microview Science & Technologies (Beijing, China;www.microview.com) to develop a vision system that images the old meters after they have been packed in cartons. "One of the essential requirements," says Yu Zhao, applications engineer at Microview, "was to capture images of the meters and read the data simultaneously-both the barcode and the numeric characters-and store the results in a database."

The cartons are moved by conveyor to one of three workstations, where an operator shunts the camera into position using a three-axis manipulator. Microview's vision system uses an IBM Server X346, three Dell 5150n workstation computers, three Iris P1200 smart cameras from Matrox Imaging (Dorval, QC, Canada;www.matrox.com) fitted with a CCTV 12-mm lens, and three OEM light sources. Image analysis is performed by the Code Reader and String Reader modules from the Matrox Imaging Library. The barcode and numeric digits that determine electricity usage are processed and compared with old data and stored in a database. When the procedure is complete for all the meters in a carton, the carton is moved to the end of the line where the meters are sorted-some are destroyed and others are sent to smaller cities to be re-used.

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