P.E.R.C.H.

This page is dedicated to the project work for the senior design group the Picker Enhancement Rover for Careful Harvesting (P.E.R.C.H.).

Introduction:


Joe Rumble owns an orchard in Washington that has grades within the orchard of up to 20 degrees. He currently has each of the workers in the orchard pick the fruit by hand and place it in a bag hanging down the worker’s chest. The worker must move around with this bag and a ladder in order to navigate the trees in the orchard. This can be a dangerous endeavor because the bag can get up to 60 pounds before it is emptied into a bin. There are also time inefficiencies in this process because of the constant re-positioning of the ladder, and the worker emptying their bag every tree or less. This was not only time consuming, but physically demanding on each of the workers. The steep grades in the orchard prevent the current picking platforms to be a viable option. Although the picking will still have to be done by hand because of the delicacy of the fruit, a machine that will aid the workers in their picking, and eliminate the constant movement of an individual ladder is our goal. The current state of the picker working conditions has not been changed in nearly 100 years, and is need of a safer, more efficient option for sloped orchards.

In order to see an orchard and the equipment that was used, the group visited Bishop's Orchard in Garfield, Washington. Although this was not our client's orchard, the sense of the slopes through the orchard were similar. The only power equipment used by this orchard was a picker lift. This was a three-wheeled device that would raise and lower a picker so that the top branches could be reached. The type of bag that was used was the same as a picker climbing a ladder, so the bag had to be emptied manually. This platform was sturdy due to the three-wheeled design, but the maneuverability of the machine was limited because the entire machine would rotate to get the arm with the picker into the correct position. This was clumsily done, and could easily cause damage to the trees because of all the branches it could hit during its movement.

Problem Specifications
Design a machine that:
 * Allows 1-2 pickers to safely and effectively pick fruit or prune trees from heights 6’ to 13’ off the ground
 * Incorporates emergency safety features
 * Propels itself effectively and efficiently on terrain that has grades as high as 20 degrees (36% grade)
 * Provides for stationary picking/pruning and remain stable on grades ranging from 7-35%
 * Incorporates a mechanism or procedure to improve the ease and speed of transporting the fruit from the tree to the bin
 * Transports 4’x4’x30” bins of up to 1100 lbs and can leave full bins behind easily and efficiently
 * Overall improves fruit picking efficiency, safety and range when compared to a traditional ladder

Main Problems

 * 1) Picker Positioning
 * 2) Bin Management
 * 3) Fruit Transport and Bin Filling

Each of these issues have been researched and potential solutions have been found.

Picker Positioning
One of the major problems that needs to be addressed is the picker positioning. The picker must be able to get into each tree to pick all of the fruit without hassle. They must be as maneuverable, or more, than they are currently with the picking ladders that they are using. The picker must be able to get from the very top of the tree, down to about 6 feet above the ground. They also need to be able to get from the near center of the tree, out to the edges to pick the most fruit possible. Current picking platforms have tiered areas where the workers stand and can move from side to side along the tree, however they are not able to reach far into the tree, so the type of orchard it can be used on is very specialized. If the orchard still has circular or oval shaped trees, the worker would be missing a lot of fruit on the inner parts of the tree.

Ladder Mechanism

One potential solution for picker positioning would be a hydraulically operated ladder mechanism. The ladder would be attached to a laterally moving bracket on rails that could move along the P.E.R.C.H.'s sides parallel to the long axis of the machine. The ladder's angle of incline would be manipulated by hydraulic pistons while the axis of rotation for the ladder would be attached to the bracket by a hinge. The ladder could also possibly bend at its midpoint hydraulically to move the ladders axis of rotation out away from the machine to create a smaller angle of incline at lower picking heights. The ladder could include a sliding safety harness that could be moved up and down the ladder to allow picker mobility.

Dual "Cherry Picker" Platforms

This solution would be based off of a normal platform, but would be hydraulically operated in order to reach in many places along the tree. The worker would not have to move along a ladder, and would be on a small platform that could move throughout the tree.

Bin Management
Bin management refers to the way the P.E.R.C.H. will house bins that are being filled and how these bins will be swapped with new, empty bins. One solution is by using forks incorporating a conveyor system much like the Bin Runner made by Crendon Machinery. There would be a set of forks on both the front and back of the P.E.R.C.H. which would incorporate two belts ran by drivetrain. The belts would run in either direction from one set of forks at one end all the way along the machine's long axis to the other set of forks. These forks can also change their angle and incorporate a guard which keeps them from digging into the ground when loading. Using this solution, the empty bins can be loaded from either the front or back of the machine and then deposited on the ground either behind or in front of the P.E.R.C.H.

Fruit Transport and Bin Filling
Transporting the fruit from the picker to the tree to the bin has to be as economic and gentle as possible. Many options have been researched in order to find a solution to this problem. Large picking platforms have been created to solve these problems on level ground, however the issue of slope of the orchard has not yet been addressed. One particular platform uses vacuum suction and tubes in order to transport the fruit from the worker to the machine. The worker has a tube strapped to them so the tube is always readily available. The tube system created by Whoosh Innovations is gentle on the fruit and is able to transport the fruit very quickly. The fruit is then put on a conveyor belt and processed by a bin filling device that deposits the fruit into the bottom of the bin, slowly raising as the bin fills.

Another system that is used currently is a platform called the Pluk-O-Trak. The picker is on a fixed platform and places the picked fruit on a conveyor belt. This small conveyor belt has cleats which separate the fruit from one another, and prevent the fruit from rolling and damaging themselves. The conveyor will lead to a larger conveyor that gathers the apples from four pickers situated at different points on the platform. The apples are then fed into a flexible vertical conveyor in order to fill the bin. The bin is rotated constantly so that the bin will fill evenly on all sides. The workers are not required to level the fruit in the bin because of this innovation.

Although both of these platforms have great innovations for harvesting fruit, the technology is new and therefore, expensive. To incorporate even part of these inventions, it would be tens of thousands of dollars. For the P.E.R.C.H. these ideas will be kept as inspiration, and alternative solutions are being considered.

For other ideas for solutions, a paper by William Messner and Brian Kliethermes on Augmented Fruit Harvesting was consulted. They present several solutions on how to handle fruit when filling bins and when transporting the fruit from the tree. Bin filling is a large issuer because this is when there is a large amount of fruit in one spot, with the greatest potential for damage. The fruit cannot be dropped into the bin, so an alternative method must be used. When commenting on conveyor systems, Messner and Kliethermes note that nearly 100% fruit singulation can be attained. This is ideal so that fruit will not be damaged by other fruit during its transportation.

Conveyor belts

Conveyor belts could be used in our design to transport the fruit away from the picker. Cleats would be incorporated on our conveyor because the picker would be up on a ladder, and the angle of the conveyor would be very steep. The picker could pick the fruit and place it on the conveyor. This would eliminate the use of bags, and would cause much less strain on the worker. The picker would also be more productive because there would be no need to climb down from the ladder to empty a bag. A conveyor belt could also be useful when collecting the fruit from several pickers and transporting it into the bin. The conveyor could have several smaller conveyors deposit onto it, and then travel to the bin.

Gravity-Fed Tubes

Since the pickers will usually be higher than the bin, a tube using gravity could feed the fruit away from the picker. A semi-flexible tube could be attached to the picker, and they could simply drop the fruit into the opening. Gravity would pull the fruit down to the bin. To slow the fruit, baffles within the tube could be placed to slow the fruit as it falls. This is a very simple solution, but would not work it the picker was level to, or below the bin they are filling.

Bin Fillers

There are several solutions on how to fill a bin with fruit quickly and gently. The vertical conveyor that is on the Pluk-O-Trak is a great solution and would only require the workers manually crank the filler to the bottom of the bin. After that sensors would take over and slowly raise the bin as the fruit filled it. Along the same idea, a sensors could be installed on a large flexible fan that would rotate and deposit fruit as it spun.

Design
The design of the PERCH has progressed continuously from an original sketch from Joe Rumble to current designs. The design has incorporated a system of the ladders to pivot at the base in order to adjust to changing slopes of any orchard. This would allow the main body of the machine to stay unadjusted on the ground, while the ladder with an orchard worker would be adjustable to the particular needs of that tree. The ladders would be able to adjust will the slope of the orchard as well as angle away from the machine to reach each individual tree. Both of these adjustments would be hydraulically operated so that operation would be smooth and effortless.

The bin runner design would also be incorporated into this design so as the PERCH was moved, the bins could be picked up, filled, and dropped off to decrease adjustment time in between bins. It would ideally hold 2 bins at once so that an empty bin could be ready the moment the first bin was full. This would make it so there would be no delay in dropping off of one bin and picking up of the next. The workers could almost work continuously without having to backtrack after replacing the bin. This would also allow more flexibility in the spacing of the bins because the amount of fruit picked from a particular section can not be estimated exactly. The preparation before picking would not have to be as precise if the machine could have a bin ready whenever it was needed.

The picker would have a conveyor belt next to the ladder so that fruit could be deposited easily. The fruit would travel down the conveyor, onto another conveyor to combine with the fruit from the other side of the PERCH and then into the bin filler fan.