Automatic Produce Grading System
The development of a machine vision system for automated high-speed produce grading is described. Image processing techniques were used to obtain an estimate of the volume of each item, which was then related to the weight through a closed-loop calibration. Accurate weight estimation led to more accurate and better control over the spread of package weights. This reduced the average package weight by approximately 20%, with a standard deviation of 2.5 g for a nominal 100 g package. Improved processing efficiencies doubled the throughput and significantly increased the profitability of the packinghouse.
A large project such as this is never a one-man effort. My role in the project related to the image and signal processing aspects. The other members of the development team were: Ralph Ball and Harvey Barraclough, who focussed on the mechanical engineering aspects of the project; Ken Mercer, who developed the intelligent actuators; Colin Plaw, who developed the LabVIEW based control system; Andrew Gilman, who investigated high-speed weighing using load cells; and Geoff Lewis from the packinghouse, who provided the test system and copious quantities of asparagus for testing.
We also acknowledge funding for this project from Technology New Zealand through a Technology for Business Growth Grant.
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