The Geiger Lund Selective Asparagus Harvester
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Tractor-pull type selective mechanical asparagus
harvester. Designed as a three or four row machine, but with
only one header mounted. Sorting station on the back where a worker
can sort and crate the asparagus. |
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We ran the harvester in Pasco Washington in the spring of 2007. The machine does a pretty nice job of harvesting the spears that are ready to be cut, typically recovering about 75 percent of the marketable spears on the bed. However, the machine damages too many of the spears that are not yet ready to be harvested, what we call "collateral damage". Especially the spears that have not yet emerged from under the ground. Because of all the missing spears from the collateral damage on previous days, our yield drops to less than 50% of what a hand crew would harvest. This last season (spring 07) Washington State University also tested the Oraka machine. The Oraka machine (from New Zealand), a robotic type harvester, uses a very similar method to cut the spears, a blade mounted on the piston rod of an air cylinder. Their blade was slightly narrower than ours and the Oraka machine only has the one blade. It centers the blade on the spear an inch or so back. Once the blade is in position, the cylinder extends, pushing the blade through the spear and into the ground. Nearly identical to the way our machine cuts. The Oraka machine caused far less collateral damage than our machine and was comparable to ours in dropped or missed spears. The Oraka machine was getting yields compared to hand on some days of 80% and higher, even exceeding 100% at least once. Even with such impressive yields the Oraka machine is currently much too slow to be economically viable. The Oraka machine clearly demonstrates that with a few changes, our cutting method can be used without the collateral damage problem. There are three main differences between the Oraka machine and the Geiger Lund machine that relate to the collateral damage problem; 1. Our blades are wider. 2. We fire too many blades at a time. 3. Our blade angle is too high. Our solutions: 1. We have designed custom air cylinders that will reduce the blade width from the current 2-1/2", wide to 1-3/4" wide. (The Oraka machine has a blade 2-1/4 inches wide.) 2. Our spear detectors have too wide of a field-of-view, and so a single spear often sets off three blades. (equivalent to a blade over 7 inches wide) We've re-designed the detectors for the proper the field-of-view for the new blade width. The Machine will fire one blade to cut a spear, or two adjacent blades if the spear lies between two blades, but it will never fire three blades at a single spear. 3. We've allowed for a lower blade angle. With these changes we expect yields of better than 70%. Unfortunately, Washington State University has decided not to continue our funding for next season. If we can find a source of
funding we will make the changes to the header, and we feel at that
point we will have a marketable machine. Or visit YouTube and search for "Asparagus Harvester". |
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About the harvester:The Geiger Lund selective mechanical asparagus harvester is primarily intended to harvest fresh market asparagus with a length of nine inches of green. An optical spear sensing system senses any spears long enough to cut and the location of the spear is fed to the electronic control system. The Control system takes a speed input off of one of the tires, and then fires the appropriate air cylinder at the right moment no mater what speed the machine is going. The machine cuts the spears at or slightly below ground level. The spears are grasped by soft rubber fingers and lifted to conveyors which transport the spears to the rear of the machine where it is sorted by one or two workers and packed into suitable containers. We've been experimenting with the machine for the past few seasons with financing from Washington State University. Here are links to some of Washington State University's pages about the asparagus harvester from past years, when it was self-propelled. http://www.agribusiness-mgmt.wsu.edu/AgbusResearch/Asparagus_harvester.htm
http://www.agribusiness-mgmt.wsu.edu/AgbusResearch/asp_selective_harvester03.htm
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