P19762: Agriculture Value Chain
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Detailed Design

Table of Contents

Team Vision for Detailed Design Phase

For this phase, we had planned to do more testing on individal parts of the system like the hand pump, solids filter, and testing for each individal sensor. Testing for most of the sensors has been done, but both the hand pump and filter need more testing. Oxygen depletion in stagnet water also needs to be tested as well. Test plans have been created for each part of the system and a general schedule has been set up for next semester. The CAD work has been finished since last review.

Progress Report

Team progress reports will also be posted here

Prototyping, Engineering Analysis, Simulation

Oxygen Sensor

O2 sensor was borrowed from Professor McCalley and we know how to use it

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Hand Pump

Since the last review, we built and tested DIY check valves. The design we choose used a bouncy ball as the seal that would block water flow in one direction and a nail was used as a retaining bar to keep the bouncy ball from being pulled into or expelled from the pump.

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We tested two bouncy ball types. One was fairly soft and the other fairly hard rubber, but both were ¾” in diameter. The tutorial we follow said to cut the bouncy ball flat on one side. It is unclear to us what the benefit of that would be, but we tested both cut and uncut designs. None of the check valves designs worked. The cut, soft bouncy ball was expelled out of the pump and the uncut, soft bouncy ball could also move out of position and get lodged in the pipes. The uncut, harder bouncy ball did not create a good enough seal to create the vacuum of the pump and the cut version was no better. Following testing, we purchased check valves in order to keep moving forward with the testing plans for next semester. We also purchased an extra check valve we will use to reverse engineer and attempt to make a new DIY design that will work.

The purchased check valves worked as expected.

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Tank Cutting

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Above is one of the 55-gallon tanks that will be used to house the fish for our system. The top was cut off with a jig-saw on the inner edge to allow for access to tank while keeping outer strength of the tank.

Drawings, Schematics, Flow Charts, Simulations

Sensor System

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This first image show in somewhat simple detail the basic ways that all of the sensors and auxiliary components will be connected together. All of the sensors use various different types of interfaces that all can be accounted for and interfaced with using the Arduino.

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This image shows, in greater detail, exactly how our current prototype is wired together. A breadboard is used to allow other components, such as switches and LEDs, to be connected to show some status of the board. This allows further designing, implementation, and testing to be made easy until a final design is decided upon and can then be built more permanently.

Bill of Material (BOM)

BOM

The table below shows all components in the current design

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A link to the current purchased materials can be found here: | Current Purchased Materials

Budget

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The above image shows the current balance as of December 3th, 2018.

Test Plans

The test plan can also be found here: Test Plan

Sensor Functionality

Objectives:

  1. Verify the accuracy of the sensor system

Engineering Requirements Addressed:

  1. ER01 - Ability to sense and record pH
  2. ER02 - Ability to sense and record temperature
  3. ER04 - Ability to sense and record turbidity

Assumptions: None

Test Setup:

  1. Set up water samples of various pH, temperature, and turbidity

Test Method:

  1. Measure pH of a water sample using the sensor system.
  2. Measure pH with a secondary, more precise tool.
  3. Compare values. Is the pH sensor in its tolerance range?
  4. Measure the temperature of a hot and cold water sample using the sensor system.
  5. Measure the temperatures with a secondary, more precise tool.
  6. Compare values. Is the temperature sensor in its tolerance range?
  7. Measure the turbidity of a clear and cloudy water sample using the sensor system.
  8. Measure the turbidity with a secondary, more precise tool.
  9. Compare values. Is the turbidity sensor in its tolerance range?

User Interface Functionality

Objective:

  1. Verify user interface works and is user-friendly.

Engineering Requirements Addressed:

  1. ER21 - User interface is simple and intuitive.

Assumptions:

  1. Testers represent the average user’s familiarity with technology.

Test Setup:

  1. Full setup of system with sensors fully setup.

Test Method:

  1. Bring in several people with zero knowledge of sensor system.
  2. Allow them to explore sensor UI and comment on pros and cons of system.
  3. Ask them yes/no if the UI is simple and intuitive.
  4. Ask for potential improvements to UI and system.

Evaporation and Leakage

Objectives:

  1. Ensure there are no leaks in the system.
  2. Determine evaporation rate during a warm, sunny week in Rochester.

Engineering Requirements Addressed:

  1. ER05 - Water volume replaced per week.

Assumptions:

  1. Climate differences between Colombia and Rochester on a warm, sunny day will not have a significant effect on the evaporation rate.

Test Setup:

  1. Setup plant bed with both fish tanks underneath in an unshaded area.
  2. Add water to plant bed and tanks.
  3. Float foam raft in the plant bed with no holes or holes plugged to mimic plants being in place.

Test Method:

  1. Mark the initial height of the water in the plant bed and both fish tanks.
  2. Leave the system untouched for a week.
  3. Mark the final height of the water in all three tanks.
  4. Calculate the difference in volume.
  5. Add any rain totals from the week to the water loss total.

Solids Filter

Objectives

  1. Make sure the solid waste filter can catch debris
  2. Use filter material that is easily cleanable

Engineering Requirements Addressed

  1. ER12 - Ability to dispose of undissolved solids

Assumptions

  1. A mix of solid fish food and dirt is an acceptable equivalent to solid fish waste for the purposes of this test.

Test Setup

  1. Fill the filter with filtering materials
  2. Close up the filter leaving only the ends open

Test Method

  1. Add solid fish food and dirt to a cup of water.
  2. Measure the turbidity.
  3. Pour most of the water through the filter, leaving some of the water in the cup.
  4. Catch the water coming through the filter in another cup.
  5. Visually compare if any solid waste made it through the filter.
  6. Measure the turbidity.
  7. Is the resulting turbidity less than or equal to 300ntu (100mg/l)?

Pump

Objectives:

  1. Determine the flow rate of the hand pump when used by the average person.
  2. Determine how the flow rate changes over long lengths of time pumping.
  3. Determine the amount of time needed to follow the possible cycling schedules.
  4. Recommend the most efficient and feasible cycling schedule.

Engineering Requirements Addressed:

  1. ER23 - Farmer interaction time per day

Assumptions:

  1. The average of the results from each team member performing the test is equivalent to the average person’s ability.

Test Setup:

  1. Fill a 55 gallon drum with water.
  2. Insert pump inlet into drum.

Test Method:

  1. Perform 20 strokes (up and down) of the hand pump.
  2. Measure and record the amount of water that comes out, and divide by 20 to find the # volume displaced per stroke.
  3. Return the water to the 55 gallon drum.
  4. Pump the water out without stopping until only air is coming out.
  5. Count strokes per minute.
  6. Record overall time.
  7. Repeat all steps with a different tester.

Short-term No-fish No-plants

Objectives:

  1. Determine if there are any obvious issues with the system.
  2. Do parameters stay in the acceptable ranges?
  3. How long does daily maintenance take?
  4. What contaminants (if any) get in the system?
  5. How much water volume is lost over the course of testing?

Engineering Requirements Addressed:

  1. ER05 - Water volume replaced per week.
  2. ER06 - Can maintain O2 level (with user interaction).
  3. ER07 - Can maintain pH level (with user interaction).
  4. ER08 - Does not create sudden pH changes in water.
  5. ER09 - Prevents contaminants from entering water.
  6. ER17 - Reliable in hot weather.
  7. ER18 - Resistant to rain.
  8. ER19 - Set-up and tear-down time.

Assumptions: None

Test Setup:

  1. Acquire all materials required for a full system build.

Test Method:

  1. Build full system.
  2. Record time it took to build.
  3. Make note of starting water volume.
  4. Record parameters from sensor system.
  5. Conduct daily pumping that would be required of a full system.
  6. Record parameters again.
  7. Make note of the weather for the day.
  8. Record any additional observations about the state of the system.
  9. Repeat steps 4 to 8 for at least a week.
  10. Record water volume loss.

Medium-term No-fish With-plants

Objectives:

  1. Test bacteria’s ability to convert ammonia at the level we expect the fish to create ammonia.
  2. Test if the converted ammonia is enough nutrients for the amount of plants we are using.

Engineering Requirements Addressed:

  1. ER05 - Water volume replaced per week.
  2. ER06 - Can maintain O2 level (with user interaction).
  3. ER07 - Can maintain pH level (with user interaction).
  4. ER08 - Does not create sudden pH changes in water.
  5. ER09 - Prevents contaminants from entering water.
  6. ER13 - Ability to dispose of dissolved solids.
  7. ER14 - Ammonia levels.
  8. ER17 - Reliable in hot weather.
  9. ER18 - Resistant to rain.

Assumptions: None

Test Setup:

  1. Use full system from previous test.
  2. Add plants to plant bed.
  3. Make note of starting water volume.

Test Method:

  1. Record parameters from sensor system.
  2. Add ammonia to fish tanks.
  3. Conduct daily pumping that would be required of a full system.
  4. Record parameters again.
  5. Make note of the weather for the day.
  6. Record any additional observations about the state of the system.
  7. Repeat for 2-3 weeks..
  8. Record water volume loss.

Long-term With-fish With-plants

Objectives:

  1. Test the full system.
  2. Determine if the chosen parameter ranges keep the fish healthy.
  3. Determine if the harvest output will be what is expected.

Engineering Requirements Addressed:

  1. ER05 - Water volume replaced per week.
  2. ER06 - Can maintain O2 level (with user interaction).
  3. ER07 - Can maintain pH level (with user interaction).
  4. ER08 - Does not create sudden pH changes in water.
  5. ER09 - Prevents contaminants from entering water.
  6. ER10 - Allows fish access to a light source.
  7. ER11 - Fish density.
  8. ER12 - Ability to dispose of undissolved solids.
  9. ER13 - Ability to dispose of dissolved solids.
  10. ER14 - Ammonia levels.
  11. ER17 - Reliable in hot weather.
  12. ER18 - Resistant to rain.
  13. ER23 - Farmer interaction time per day.
  14. ER26 - Protein output.
  15. ER27 - Carbohydrate output.
  16. ER28 - Fat output.

Assumptions:

  1. A month is a long enough time frame to determine if the system is viable.

Test Setup:

  1. Use full system from previous test.
  2. Add fish to fish tanks.
  3. Make note of starting water volume.

Test Method:

  1. Record parameters from sensor system.
  2. Record water volume loss.
  3. Add water if needed.
  4. Clean filter if needed.
  5. Conduct daily pumping.
  6. Record parameters again.
  7. Adjust pH, oxygen levels, etc. as needed.
  8. Feed the fish.
  9. Record farmer interaction time.
  10. Make note of the weather for the day.
  11. Record any additional observations about the state of the system.
  12. Repeat for a month.

Test Ways of Adjusting pH, oxygen levels, etc.

Objectives:
  1. Determine best way to adjust pH.
  2. Determine best way to adjust oxygen level.
  3. Determine best way to adjust turbidity.
  4. Determine best way to adjust ammonia level.

We are holding off on making this detailed test plan until we talk to Marty from the Greenhouse Cafe to get his input on how he maintains the parameters in his system.

Risk Assessment

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The risk assessment document can be found here

Design Review Materials

The pre-read for the Detailed Design Review can be found here

The testing plan document can be found here

Plans for next phase

January to Spring Break

Spring break to Imagine

The schedule for next semester can be found Here


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