Apple of your eye

Citation

(2003), "Apple of your eye", Industrial Robot, Vol. 30 No. 6. https://doi.org/10.1108/ir.2003.04930faf.001

Apple of your eye

Apple of your eye

Keywords: Inspection, Agriculture, Fruits, Robots

A robot has been developed to take over the laborious task of packing apples for supermarkets, reducing costs by almost 60 percent and freeing up key workers for other vital duties at harvest time. Core to its operation is the control of Hoerbiger-Origa precision electric linear drives via intelligent information generated by a state-of-the-art vision system (Plate 1).

Supermarkets insist that the attractive side of the apple is displayed to the customers, so their buyers require the suppliers to undertake this responsibility during the packing processes. To date this has meant huge expense in packing millions of apples manually one-by-one. But at this year's Hanover Fair the first credible alternative, Apfelrobo, was displayed by Hoerbiger-Origa.

Apfelrobo was developed in conjunction with Hermann Schuster, an Austrian company specialist in fruit technologies and since the show it has entered series production. It is expected that about 25 robots will be deployed into the logistic chain this year, and a further 50 next year.

The machine works in several discrete stages. Apples are delivered via a conveyor and each is individually picked up by a suction cup on a belt-driven actuator, then an air stream is used to rotate the apple until the stalk stands vertically upright.

Next comes Apfelrobo's core function: the apple is rotated through 360° under the watchful eye of the vision system, which is looking for the reddest area.

This is determined in real time and the apple rotated, backwards or forwards, as the apple is transferred and lowered onto the packaging pallet. For absolute perfection the stalks of all the apples are arranged to point backwards, away from the final customers' viewing position in the supermarket Apfelrobo finally packs the filled pallets into boxes and places them onto an exit conveyor belt to continue their journey to the high street.

All movement axes are based on Hoerbiger-Origa OSP-E electric liner drives. In this case, belt drive models are used in preference to ballscrew units because their robust construction requires minimal maintenance. In fact the maintenance interval is 3,000km of travel far greater than that of any comparable actuator on the market, and this comes around remarkably quickly as the robot is likely to be working 16 or 20h a day, 7 days a week.

During development of Apfelrobo, ballscrew drives were used, but Schuster was delighted that Hoerbiger could replace these with belt units for field deployment, as simplicity of design is very attractive in agricultural and related environments. Similarly the original servo motors were replaced with steppers on the final design.

High speed and precision was required of the drive axes, as throughput is high. Similarly the vision system was required to work in real-time, as no delays could be tolerated. In fact the inspection rotation of the apple, the analysis to determine its best aspect and subsequent rotation to its final position has to be undertaken within 500 ms.

The total time allowed for Apfelrobo to complete all its functions is 2.5 s per apple, so that a productivity of 300 kg/h can be maintained. This is roughly equal to the performance of a person working at their best, without stopping for breaks or slowing down due to fatigue, a target figure often used when converting a manual process into an automated one so that bottlenecks are not created further downstream. It is expected that speed increase will follow over a period of time as the industry becomes used to automation. Additionally, the machine is about twice as accurate as a person.

Packaging costs have been reduced by about Euro 0.02 per kg (i.e. 1.5p per kg) - a saving of £4.50/h or up to £750/week and gives a payback time measured in months.

For more information, please contact: Ray Barnes, Hoerbiger-Origa Limited, Tewkesbury Industrial Estate, Tewkesbury, Gloucestershire, GL20 8ND. Tel: 01684 850000; E-mail: ray.barnes@hoerbiger-origa.com; Web site: www.hoerbiger-origia.com

Plate 1 Vision and movement: arranging thousands of apples an hour for best presentation