Image Analysis of Pellet Size for a Control System in Industrial Feed Production

Martin Georg Ljungqvist,Stina Frosch,Bjarne Kjær Ersbøll,Michael Engelbrecht Nielsen,Guy J-P Schumann

doi:10.1371/journal.pone.0026492

Martin Georg Ljungqvist, Stina Frosch + Show 3 more

Open Access

https://doi.org/10.1371/journal.pone.0026492

Copy DOI

Journal: PloS one	Publication Date: Oct 21, 2011
Citations: 30	License type: CC BY 4.0

Affiliation: Technical University of Denmark

Abstract

When producing aquaculture fish feed pellets, the size of the output product is of immense importance. As the production method cannot produce pellets of constant and uniform size using constant machine settings, there is a demand for size control. Fish fed with feed pellets of improper size are prone to not grow as expected, which is undesirable to the aquaculture industry. In this paper an image analysis method is proposed for automatic size-monitoring of pellets. This is called granulometry and the method used here is based on the mathematical morphological opening operation. In the proposed method, no image object segmentation is needed. The results show that it is possible to extract a general size distribution from an image of piled disordered pellets representing both length and diameter of the pellets in combination as an area.

Highlights

In the aquaculture industry it is of outmost importance that the fish get feed of proper size
In the initial image analysis of single pellets, the size of 24 pellets at production start was compared to the size of 24 pellets at production stop, see Figures 8 and 9
For robust results of the size measurement, the image contrast should be as high as possible. Previous work in this field has used segmentation before the morphological opening step, which could be a source of error and it consumes computation time

Summary

Introduction

In the aquaculture industry it is of outmost importance that the fish get feed of proper size. The feed is usually in pellet form, where the pellets contain the nutrients that the fish need to grow and stay healthy. It has been shown that growth rate of fish is closely related to the pellet size of feed [1,2,3]. When producing feed pellets for aquaculture there is a need to control the size of the output product, and this is a challenging task. An extruder machine is commonly used for fish feed production. The feed material is extruded through a die plate with holes of a certain diameter which determines the diameter of the pellets. The length of the pellets is affected both by the velocity of the knives and the pressure inside the machine

Objectives

Methods

Results

Conclusion