FETCH

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Team Members

Kora Barnes

Kora Barnes hails from the state of Montana. Her interest in all things outdoors as well as control systems and electronics attracted her to F.E.T.C.H. She is a senior in Electrical Engineering looking at graduating in December 2013. After receiving her Bachelors she will either look for jobs in embedded design or head to graduate school. When she finds a bit of free time she enjoys skiing, rugby, soccer, rock climbing, or board games.

Joshua Burns

Elliot Dickison

Elliot is a senior in Computer Engineering hoping to graduate this fall. He signed up for F.E.T.C.H. because of an interest in quadcopters and a love for the outdoors. He is currently working as a web developer at Economic Modeling Specialists International. He enjoys speaking spanish, skiing, photography, and the web.

Eric Johnston

Eric Johnston is a Senior in Electrical Engineering with an expected graduation in spring of 2014. He signed up for F.E.T.C.H because he loves working with microcontrollers and small electronics, as well as being outdoors. He is currently involved in research for the Advanced Pedestrian Crossing system and with the school’s Electromagnetic Accelerator project, in addition to being a tour guide for the University. In his free time he likes to ski, camp, play video games, and target practice.

Brian Lee

Brian Lee is a Computer Engineering Major at the University of Idaho. He has focused mainly on embedded systems. Has worked in retail, IT, and horse training.

Colby Rush

Colby Rush is a Senior undergraduate majoring in Computer Science, with an expected graduation in Spring 2014. He signed up for the FETCH project because he was interested in the unique application of CS in regards to this project, and the opportunity to design his own software. He is handling the local application aspect of data storage, in tandem with Gresham Schlect.

Gresham Schlect

Gresham Schlect is a senior studying Computer Science. He enjoys the FETCH project because it gives him the opportunity to work in engineering fields other than CS, but where similar problem-solving skills are required.

Problem Definition

Stakeholders

Stakeholders: The stakeholders in this project are the sponsoring College of Natural Resources, the University of Idaho, and any future students who may need sun foliage research material.

Target Specifications

  • Quad-copter design for stability, ease of assembly, and portability
  • LEDs mounted on the quad-copter to provide for low-light circumstances
  • Integrated GPS flight board functionality to maintain quad-copter location information and aide in directing
  • Mounted cameras for added flight visibility
  • Lattice-work extendable arm for variable extension lengths
  • Cut-and-hold sheers for foliage sample retention
  • Off-the-shelf parts for easy repair
  • LiPo 3 cell batteries and charger for thrust and flight power
  • Basestation device to store relevant data on an application about the retrieved sample while in the field, as well as a server to store the collected data for later analysis.

Background

The University of Idaho College of Natural Resources (CNR) does extensive research into various types of trees throughout Idaho state. However, in order to conduct some areas of study, students must gather hard-to-access materials for research. Some of these materials include samples of "sun foliage." This term constitutes the upper-most branches of a tree which have the most exposure to sunlight. Because of this exposure, they are the most optimal specimens to use in researching the tree itself. Currently, there are three common methods used to extract this type of foliage:

1. Transported Crane - The most expensive current method involves transporting a crane onto the scene with the desired trees. Using a crane means that the sun-foliage of even the highest trees is usually easily accessible. However, this involves renting and transporting a crane, as well as hiring a crane operator to help with sample gathering. It also limits the amount of trees that are easily accessible, as the body of the crane must be moved whenever a tree is out of reach. Thus, while it may be useful in a small clearing, where one can easily reach various different trees, it is not as efficient in a remote, tightly forested area.

2. Tree Climbers - This method involves individuals climbing the trees to the very top where individual samples will be collected. With the proper safety training and harnesses, this can be a very fruitful method. The time required to ascend and descend each individual tree is extensive, though, meaning that it may take an inordinate amount of time to gather a respectable amount of samples. It also involves risking the individual climber, as the samples are often collected directly before the dawn hours when sight may be limited.

3. Shotgun - Using a shotgun is the most common method employed by the University of Idaho in collecting sun foliage. It envolves an individual standing at the base of the tree and shooting upwards, aiming at the particular branch desired. This method is relatively inexpensive, and only requires one collector in the field. It is not the most efficient collection method, however, as it usually involves multiple shots with even the most skilled individual. Even when the branch is finally cut by the bullet, it is not guaranteed that it will fall to where the researcher can collect it.

Goal

The project goal is to produce a fully working prototype by the end of Fall 2013. This prototype will be able to fly and reliably cut the uppermost branches of the trees researched by the CNR department.

Team Makeup and General Planning

The team will include six students, from electrical engineering, computer engineering, and computer science. Hardware development will include ordering the proper materials in order to construct a portable quadcopter, and the lattice arm attachment that will contain the clippers to gather the top-most branches of trees. Software wise, microgrid controllers will be programmed to lower and raise the arm, close and open the clippers, and control the direction of the quadcopter's flight. There will also be an application on a laptop to be taken in the field, used to store information about the samples collected. Once back at the lab, the data will be transferred to a server for later analysis and documentation.

The first semester of this project included six students. These students represented the electrical engineering, computer engineering, and computer science departments from the University of Idaho. The second semester of the project included seven students, replacing the two computer science students and adding a new electrical engineering student.

In the course of developing the hardware for this project, the team decided that power, visibility, and accuracy would be the most important design features for the F.E.T.C.H. product. Power is necessary in order to provide the force necessary for the quad copter to fly. Visibility is required in order to ensure device safety. Accuracy must be high in order to prove that the quad copter to more effective than current methods.

The process of hardware development has included putting together and ordering a list of needed materials. These materials were chosen for their physical and computational power, so that they might better contribute to the strength of the design. The materials have been ordered are on route to the University of Idaho, where they will be assembled into the quad-copter and its lattice-work arm attachment.

For software, the final product will include both a flight controller fully programmed microcontroller, the application, and the server. The flight controller has been pre-programmed to help the operator correct for balance in higher altitudes, and also includes a GPS for easy location. The microcontroller will control the lattice-work arm and it's cutting implement. Currently, the flight controller is in transit with other quad-copter hardware. The microcontroller has been programmed to light the quad copter LEDs with push-button control, and control DC motor movement with RC controller signals.

The 2nd semester computer science students will be responsible for an auxiliary software application to store and index sample data, to help researchers keep track of the samples that they collect using the quadcopter. The application is nearing completion and the server is ready receive the data.

Concepts

Functional Requirements

  • Payload: Ability to carry small foliage samples (approx 20cm in length, 2.5cm in width)
  • Transportation: Must be able be carried in a common automotive vehicle.
  • Location: Must operate in remote areas that may have dense or sparse tree populations
  • Battery time: Between 3 and 4 hours, if at all possible.
  • Webcam: extremely desirable, in order to see what branches are optimal
  • Range minimum: 4 meters
  • Range maximum: 50-75 meters+
  • Number of operators: 1
  • Training: 2 hours maximum for an operator.
  • Flight times: Able to fly in low-to-no light conditions

Beginning Project Concepts

The Flying Device

  • Helicopter - For weight management and power conservation the team originally considered using a simple helicopter design. However, high altitudes, wind conditions, and payload weight might upset the balance of the single propellor.
  • Quadcopter - The strength of the quadcopter lies in its cross design, which provides a central point of strength in the middle. With four propellors, it also is easier to maintain balance in flight.
  • Octocopter - Octocopters are also well balanced, as there are many propellors to correct any problems during flight. They are also generally heavier than other flight device, due to the added motors. They are also more expensive.

The Arm

  • Hinge extension - This would involve the arm being a single length that was lowered from a hinge joint on the flight device This is a simple, efficient design, that can be very light weight. It is also fragile, and has the possibility of throwing off the balance of the flight device during extension.
  • Telescoping extension - Using this method, the arm would consist of layers of tubing nested within one another, which extended in a manner similar to a telescope. This is a lightweight mechanism, but also fragile and complicated.
  • Lattice work - This mechanism consists of a latticework arm framework, controlled by a gear rack. As this gear rack decremented or incremented, the ends of the framework would contract or expand, with would in turn retract or extend the arm. This design is heavier, but also more sturdy. It also provides easy length variability.
  • Extend from side - The idea behind this design would be that the arm would extend to one side of the flight device, which would in turn fly next to a tree. This is easy to understand, but will likely be detrimental to the flight device balance.
  • Extend from bottom, then side - To correct for the possible weight imbalance, and provide more distance between propellers and tree limbs, this design would drop below the flight device. Once it had extended a certain amount, it would then reach out sideways towards the tree. This is a more functional design, but there exists a problem in different branch angles.
  • Extend straight down - This design would optimize both balance and branch-cutting angle. By extending straight down from the flying device, it could easily cut branches. However, if the flight device looses control, the arm will be more likely to hit the tree it is sampling. In this case, it will probably break.

The Cutting Attachment

  • Saw - This method would see the use of a small saw in detaching sun foliage branches from the tree. Miniature saws provide quick cutting motion, and are easy to replace if damaged. On the other hand, the teeth of the saw might get caught in the branch and upset the balance of the flight device.
  • Shears - Using shears would require them to be mounted at the end of the arm attachment, and operated using the force of some separate mechanism. This provides a steady cutting force, provided that the shears are sharp. There is also the possibility of being able to maintain grip of the sample branch. There is the opportunity for rusting, though, and shears are far heavier than saws.

Concept Selection Process

The Flight Device

In the final design concept, a quadcopter was chosen. Functionally, this is because a quadcopter provides the most balance with the least amount of weight. Economically, it is also the most affordable, stable structure that Team FETCH can afford.

The Arm

A lattice-work arm extending straight below the quadcopter was decided on. Though it is slightly heavier than other design possibilities, it is also the least fragile and easiest to fix. Extending straight down will also give the propellors a wide berth in their operation, which is a good safety feature for the quadcopter hardware.

The Cutting Attachment

Shears, specifically cut-and-hold pruners, were the chosen solution for collecting branch samples. This is because they provide a steady, easily controlled cutting motion that saw blades cannot quite achieve. Cut-and-hold shears also come with an added plastic attachment that provides the operator with the ability to maintain their grip on the branch samples for easy collection.


Design

Quadcopter Design

  • Frame - Turnigy Talon V2
  • Motors - NX-4008 620kv
  • ESCs - Turnigy Plush 40amp
  • Servo Wire - Flat 26AWG
  • Flight Controller - DJI Naza
  • Battery - Turnigy 2200mAh 3S 30C
  • Battery Charger - Duratrax Onyx 245
  • Propellors - APC 10x4.7 SF
  • CR Propellors - APC 10x4.7 SFP Pusher
  • Low Voltage Alarm - On Board Lipoly
  • Battery Connectors - Traxxas Style Male & Female
  • Battery Wire Shrink Wrap
  • Servo Wire Shrink Wrap
  • Bullet Connectors

Arm Design

  • Lattice Work Structure - Plastic C-Tubing
  • Lattice Work Connectors - Nuts, bolts, washers
  • Extender Motor - Linear Stepper Motor
  • Cuttng Motor - Linear Stepper Motor
  • Shears - Cut and Hold Garden Shears

Software Design

  • Camera - 2 Wireless Cameras, attached to copter and arm
  • Screen - Windows 7 Laptop with USB Ports