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Emerald Group Publishing Limited
Copyright © 2010, Emerald Group Publishing Limited
Do not squeeze the fruit, just grade and pack
Article Type: Mini features From: Industrial Robot: An International Journal, Volume 37, Issue 1
Kiwi fruit growers and marketers in New Zealand (NZ) now have robotics to help them improve product quality and reduce costs of grading and packing fruit for shipment around the world. Close behind, apple growers in New Zealand and Washington State, the USA will also be packing apples with robots.
Zespri, a kiwi fruit marketing organization based in Mt. Maunganui, NZ, turned to the School of Engineering and Technology at Massey University in Auckland, NZ for help with solving both a labour shortage and a quality control problem. Zespri, who markets to more than 60 countries, estimates that more than 19 million dollars (NZ) per year is being lost due to offshore returns of problem fruit. The fruit marketing group is also concerned by the growing shortage of labour available to process kiwi fruit.
Dr Rory Flemmer, a Professor at the school, led the team of staff and students who designed and constructed the robotic weighing, grading and packing system. The unit can weigh each kiwi to within 0.1 g. A vision system coupled with an artificial intelligence software package can evaluate blemishes and soft spots on each kiwi against Zespri product quality standards. Three cameras scan the fruit as it passes by. An HMI display panel enables the operator to observe the vision system images and control the system (Figure 1).
Next a label is applied and each kiwi is carefully packed in trays for shipment. Fruit, which does not meet standards, is allowed to go to the end of the conveyor and into a reject tote. The computer tabulates data on the fruit processed and where necessary, can custom pack fruit for specific market requirements. Knowing the ripeness of fruit permits the cold storage warehouse staff to determine which fruit to ship and at what time. Growers will also be able to obtain feedback on product size, degree of ripeness and blemishes. Apple growers are also working with Professor Flemmer and the Massey University team to adapt the Massey technology to apple packing.
Fruit moves through the system on a rotating soft roller conveyor system. The rollers turn while moving the fruit across the weighing station to inspection, labeling and to packing. The vision system both grades and locates each piece of fruit. Software then creates real time commands to direct the labeling arm and the SCARA style robot pickup arms. The roller conveyor system also singulates the fruit so each piece can be examined separately (Figure 2).
At the end of the line a custom deigned vacuum end-of-arm gripper gently picks up each piece of fruit and transfers it to the shipping container. The control computer keeps track of the packing scheme to insure a “full pack” for each shipping tray. A complete grading and packing system consists of nine robots serving four lanes with a capacity of 250-400 trays/h.
An interesting twist on utilization of the system is that plans are underway to transport the kiwi packing systems back and forward between New Zealand and Italy. Both countries grow kiwis but harvest six months apart since they are on opposite sides of the equator and their winters and summers are different.
Zespri and Dr Flemmer are not content with just grading and packing kiwi or apples. Work is under way to develop a robotic kiwi picking system. Kiwi grows in bunches on vines much like grapes. The picking unit will operate underneath the “roof” of vines where kiwi grow, further reducing the amount of direct labour necessary to get fruit from field to market.