Rapid sorting machine sends tomato plant to the right exit

The plant grower Westland Plantenkwekerij started sorting tomato seedlings automatically last year.

This three-dimensional sorting technology is much more reliable than 2D techniques.
Erik van der Arend, director/owner of Westlandse Plantenkwekerij

Every second, five tomato plants go on the sorting machine's conveyor belt. There, a computer makes a 3D inspection and sorts the plant into one of three categories, or possibly into the fourth category, "rejected," if the judgement is negative.

Erik van der Arend, the director and owner of the plant growing company, installed the machine at the WPK location in Made. He explains how the machine works. 'A robot arm tilts the seedlings out of a tray and places them on the sorting belt. Then, at a rate of 18,000 an hour, the plants disappear into a "box", where ten cameras take a picture of them. Based on the photos, the computer calculates the mass of each plant. Then the plants are sent to the appropriate exit. This three-dimensional sorting technology is much more reliable than 2D techniques, which only look at the plant's height and width and give much less accurate results.'

The sorting machine sorts tomato seedlings automatically

Sorting tomatoes on Plant's mass

The machine comes out of the MARVIN project, which is financed by a consortium of plant growing and breeding companies and the branch organisation Plantum. Wageningen University & Research Food & Biobased Research developed the technology, and Flier Systems built the machine, which at present only sorts based on the plant's mass. Van der Arend says, 'Originally, the machine was supposed to be able to sort on many more characteristics. Some tomato varieties can have very specific defects. The ultimate goal is that the machine can sort the plants on that basis too. But for the time being, the decision was made to sort just on the basis of mass.'

The reason for this is simple. Tests have shown that the machine didn't know what to do with the more than seventy sorting variables. Van der Arend says, 'It turned out that it was still too complex technically for the machine to be able to sort on the basis of all those different variables at a high speed.'

High quality gains

The researchers at Wageningen University & Research want to take the final step within the European Plant Phenotyping Network, a European follow-up project to the MARVIN project. The goal is to fine-tune the machine so that it can sort based on all the relevant characteristics. But the gain in the quality of sorting is already huge, says Van der Arend. And what is also important, he will earn back the purchasing costs within five years.

This technology can be used for much more than just sorting tomatoes. In fact, the tomato is a relatively complex plant. For this reason, the researchers at Wageningen University & Research Food & Biobased Research are also testing relatively simpler crops such as cabbage, cucumber, and sweet pepper.

This testimonial was first published in Dutch in the Food & Biobased newsletter of January 2012.