Smart fruit grading equipment

Supermarkets like to display boxes full of high quality, consistent looking fruit. So, to help them make the grade, New Zealand fruit exporters are employing increasingly sophisticated technology in the packhouse.

A joint project between fruit grading equipment manufacturer Horticultural Automation and Industrial Research has produced machine vision technology that enables immediate identification of surface defects and colour characteristics. Improved grading means better product differentiation and therefore better financial returns to growers.

Horticultural Automation’s managing director Hamish Kennedy says colour and defect grading represent the most labour intensive parts of the packhouse.

"In terms of the market there is an increasing need by our customers to have more accurate, more consistent and more cost effective ways of sorting fruit," he says.

"We found that apples are one of the most difficult fruit to grade because of the variation in colour, so if you can do apples you can do most other fruit."

Horticultural Automation had already begun developing a system that could grade apples based on colour using video cameras. With Industrial Research’s help in a project part-funded by the Technology for Business Growth Scheme this has been extended to include surface defect detection.

The defect grading system is based on a number of cameras mounted above a section of the conveyor belt carrying the fruit. The fruit is rotated as it travels along enabling all of the fruit’s surface to be viewed by the cameras. Several overlapping photos are taken and pieced together by the computer to form a complete image of the fruit. The computer automatically grades it according to parameters set by the packhouse.

All this takes just one-fifth of a second per fruit to complete.

Chris Bowman of Industrial Research says one of the most difficult parts of the project was differentiating the apple’s stem and calyx features from true defects. The calyx is the remnant of the flower on the underside of the apple. While this has mostly been solved, the machine is set up so that whenever it is not sure it will run the fruit past an operator for checking.

As well as Australasian sales, Horticultural Automation's Hamish Kennedy expects to sell the sophisticated grading equipment in Europe within the next twelve months

Hamish Kennedy says the defect grading component is priced from $100,000 up depending on the sophistication required, while a complete grading system costs anywhere from $100,000 to $1 million. Systems are tailored to suit customers’ operations with about 90 percent of the components being common to all.

"It’s a little bit like a Lego set that you can put together in lots of different ways." He predicts a large percentage of their machines will incorporate the defect and colour technology in the future. The new system can also be attached to most older machines as an add-on.

Horticultural Automation are continuing to refine the system using their own in-house R&D staff.

"Industrial Research has given us the step up and now we’ve got our own skilled people continuing to work on it. IRL’s input was invaluable in getting the knowledge base together," Hamish Kennedy says.

At present the defect grader is being trialed on apples at a Hastings packhouse, with another already installed in Australia to grade washed potatoes. There has also been strong interest from Europe in the defect grader and exports to this region are expected within the next 12 months.