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Section 2 Final Presentation

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SMART GOAL

By May of 2021, we as JMU Sophomore Engineering Students will have worked with Northrop Grumman to develop an energy harvesting buoy. This will have a self-locating structure with a communication system which is able to support the sensor systems of our users that track oyster habitats in the Chesapeake Bay and turtle populations along the Florida coastline. This data will then be used by our stakeholders to help address the ecological problems that they work to solve.

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Final Design Solution

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Comms

Structure

Energy

Structure

Communications

Energy

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Structure Requirements

Buoy will be stable in water
Buoy will be lightweight for transportation
Buoy will be small in size for transportation
Buoy will be able to hold desired weight of Comms & Energy components

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Structure Subsystem Evolution

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Structure Experiments and Results

Maximum Weight Test (157 lbs.)

Inclining Test with 70 lbs with a 6° Rotation

34°

6°

Maximum Angle Test (34°)

Matt: In our experiments and tests, we performed a Maximum weight test, stability test, and maximum angle test. From the maximum Weight Test was can understand the weight the buoy can support until it fails. We found this to be 157 lbs.

An Inclining Test is a stability test where a structure is intentionally moved to become angled in the water based on certain applied weights on either side. The moment caused from this and the angle created are then used to measure the center of gravity and stability represented by GM. We found that when 70 lbs were placed on the left side of the buy there was a 6 degree rotation and as a result our GM was 0.451.

A Maximum Angle Test is based on understanding the Douglas Sea Scale and the wave height our buoy can withstand. When placing it at 34 degrees, we found that using trigonometry the buoy could roughly withstand a 0.6 meter wave, placing it at a sea scale of 3.

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Structure Final Design

Matt: After our design was finished, we looked back to see if we met our design requirements stated in our “structure requirements slide”. Our first requirement was for the buoy to be stable. This requirement was found and shown to be a success. Not only could our buoy hold 70 pounds on one side with only a 6 degree angle of rotation, but the GM, discussed in the previous slide, was .451, therefore meaning our buoy was stable. The second requirement set was in terms of weight. We stated that our buoy needed to be lightweight for transportation. Our definition for lightweight is less than 50 pounds. This requirement was not met due to our total weight being 53.682 pounds. Though this was very close to our original requirement we counted this as a failure. The third requirement was for the buoy to be small in size for easy transportation. We defined “small in size” as taking up a space smaller than 50 x 50 x 50 cubic inches in volume. Our final design, while easily transportable with 2 or more people, does takes up a volume of 49 x 50.5 x 18 cubic inches so it does not meet our initial requirements. Lastly, our final requirement was for the buoy to be able to hold the weight of the required comms and energy components, these required components have a total weight of 36.25 pounds. And our buoy can hold an absolute maximum of 157 pounds, meaning that we achieved this initial requirement.

I’ll now pass it over to Tyler for the Energy

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Energy Design Requirements

Buoy must be able to power its components for 7 days
Buoy must be able to store energy to power components
Buoy must be able to produce power by harvesting energy from its environment

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ENERGY SUBSYSTEM EVOLUTION

-Two solar panels

-linear regulators independently powering the comms equipment

-one solar panel

-switching regulator powering a raspberry pi

-Jumper cables powering pi

-one solar panel

-switching regulator

-USB C powering pi

-organized components

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10 gauge wire

14 gauge wire

USB C

Charge controller

panel

battery

DC load

12 V to 5 V regulator

12 V

35 Ah

battery

Raspberry pi 4

50 watt solar panel

Final design

�

Energy Final design

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Communications Design Requirements

Buoy will be able to identify location

Buoy will be able to transmit location data

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Communications Evolution

2.1 miles

Longitude and Latitude

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Comms Final Design

LoRa Chip

433MHz

Arduino

ATmega32u4

Raspberry Pi 4B

ARM Cortex-A53 1.4GHz

Ultimate GPS

Radio Antenna

3dBm

GPS Antenna

28dBm

Connections Key:

-uFL to SMA

- micro USB

to USB

Power In

-165dBm

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Section Integration

10 gauge wire

14 gauge wire

Key

Micro USB to USB
uFL to SMA
USB C
10 gauge wire
14 gauge wire

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Section Integration

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Strategy for implementation

Charging during the day, comms running at night

This model assumes that the comms team is drawing .4A (conservative estimate) between the hours of 7pm to 7am. The highlighted area indicates the discharging window. The battery should finish charging by 1pm. (To get % battery remaining, take the existing Ah, divide by 35, multiply by 100)

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Validation

	Our Goal	Products Specced	Ideal Goal	Actual
Weight Limit	36.25 lbs	-	-	157 lbs
Stability	GM > 0	-	-	0.451
Total Weight	50 lbs	-	-	53.682 lbs
Size of Buoy	50 in x 50 in x 50 in	-	-	49 in x 50.5 in x 18 in
Charge Storage	150 Amp Hours	35 Amp Hours	-	35 Amp Hour battery pulling 0.4 amps
Power Produced	120 Watts	50 Watts	-	16.9 Watts (Average)
Battery Life	7 Days	-	-	Dependent on deployment strategy
Distance	1 mile	9 miles	12 miles	2.1 miles
Bandwidth	10kbps	37kbps	-	1.4kbps
Location	Longitude, Latitude	Longitude, Latitude	Longitude, Latitude	Longitude, Latitude

Matt: Based the design requirements set by each of our subteams and provided to us by Northrop Grumman our team, reflected on how our design compares. Some of the experimental values we found exceeded the goals set at the beginning of the semester such as the external weight the buoy would be able to hold. While other design requirements were not met such as the range our radio system could transmit which we found to be a maximum of 2.1 miles. We recognize that some of these goals fall short that were established by Brevard County Zoo and the Chesapeake Bay Foundation. More specifically the total weight of the buoy, the charge storage, the charge power, the transmitting distance, and the bandwidth. As a result, Our buoy currently, would not last a prolonged period of time out on the water.

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Design Scale Up

How to make the buoy last for a prolonged period in the ocean?

Improve Sea State level by widening base
Protective layer over pool noodles to address UV deterioration
Buy a battery with a longer life span

How can the buoy support additional loads?

Increase amp-hour rating of battery or amount of solar panels
Buy a larger junction box with same rating

How can the buoys communication system transmit data a longer distance?

Switch antennas to directional antennas
Create a buoy network to communicate with each other

How can the buoy maintain temperature control?

Implement an active cooling system

How can the buoy include a fail-safe plan?

Code radios to send message when battery depletes to certain amount

Matt: We have come up with some suggestions when scaling up the design in order to achieve these goals. Some suggestions include:

Improving the sea state of the buoy we can widen the base to allow it to handle larger waves as well as enclosing the base in a hard protective layer to prevent the material from deteriorating. We also know that additional loads will be added to the buoy for research purposes so if more power is needed a larger battery or additional solar panels could be added and it is also recommended to consider a larger junction box to fit more items inside. The radio system was not able to transmit the 12 miles that was originally asked. A directional antenna could be added to increase that range or creating a buoy network to communicate to one another in shorter distances could also be created. We believe as our design currently stand there would be some problem with temperature control especially down in Florida so an active cooling can be added as well. The final aspect our team considered was a fail safe plan in case the buoy died which meant it was no longer able to send data including location so a adjustment to the code to recognize when the battery dips below a certain point can also be used.

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Section Retrospective

That concluded our final design for the buoy and as our semester drew to a close we ended with a retrospective as that is the final part of the SCRUM process we followed for designing. Each of our subteams reflecting on what went well for them and what didn't go well for them throughout the semester and then as a class we discovered and discussed the overlaps we had between teams. Examples of things that went well during our process was we all felt that we utilized our outside resources well, whether that would be the labs within the engineering department and the machines they have, the connections we made with professors and faculty of JMU who helped us understand and create our system and also the other teams who we were able to talk to and discuss the success and failures of similar systems and designs to better understand our own. Our class also felt that we spent the time this semester to prioritize the people in our group and the learning rather than the deliverable which helped us maintain good teamwork, open communication and ensured everyone had autonomy to make their own decisions while keeping the rest of the team informed as well. Some examples of things our team found did not go as well as we hoped was the integration our our subsystem together to create one buoy. There was a heavy focus at the beginning of the semester on the subteams as individuals rather than a buoy as a whole. This ultimately lead to challenges when it was time to combine all of our efforts together. During this phase of the project our teams also found it increasingly difficult to maintain the same level of communication from all classmates as the meetings size increased from 6 to 7 people to over 20 which making scheduling difficult. Our team considered ways to improve on some of these shortfalls and decided that more structured meetings between subteams or divisions within a project before integration would be helpful as well as continuing to have smaller subteam meetings during the integration phase to make sure everyone was able to remain included in the project an their ideas were heard. Our next year at JMU will be spent doing a two year capstone project and we hope to take these thoughts and reflections and apply them to our various projects of interests to help us become more successful in managing a larger scale project and completing complicated and subdivided team such as this project.

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Thank you

Questions?

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Scaling Up The Design To Meet Additional Loading

Bigger battery
Extra panels (series/parallel); roughly >150Wh/day each.
Challenges with wiring/charge controller.

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Our First Conceptual Design

Based on the component benchmarking we did last semester, our team created our original sketch of the system. The main technology we would choose to work with was LoRa to transmit data.

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POC Testing

After researching the benefits and limitations of LoRa we began testing our system by finding the maximum distance of the radios, which we found to be 2.1 miles. Bandwidth?

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Alpha Test

Talk about our alpha test, what went well and what didn’t go well
Talk about how we moved on from there in preparation for the beta test and validation test
Include picture of system used for alpha test then have picture of final system
Include picture of the Neema Code from the GPS and then showing the actual longitude and latitude coordinates

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Structure Test Calculations

Calculated Buoyancy Force

Stability Results and Calculations

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Structure Implementation

Solidworks Model of Polycase Junction Box with IP68 Rating

Multimeter and Thermocouple used to monitor temperature in Junction box over a period of time

Passive Ventilation System on the top of Box

Cable Glands to feed wires through and remains waterproof based on IP68 Rating

The Container selection was a big topic for our sub-team. For our original container we selected a Weathertight 19qt tote. This container was tested for a watertight seal and failed miserably. When the box was filled with weight and was submerged only about 4 inches above the lid for about 10 seconds and removed from the water, we recorded roughly a half of an inch of standing water at the bottom. With this in mind we knew we needed a box that performed much better in terms of being waterproof. We wanted to select a container that was could withstand heavy rain, harsh jets of water, and periods of immersion under water. With these requirements in mind we selected the Polycase junction box that we are using.This box has an IP68 rating which meets the requirements we created therefore ensuring the internal components are safe from outside elements such as dust, sand, and water.

When using a multimeter and thermocouple we found that there was a 2.5 degree increase inside the box over a period of 30 minutes. Additional Active cooling can be installed to sacrifice the watertight seal for better temperature control

Would would have liked to do further testing regarding creating a automatic system to monitor the internal temperature of the box based on a Wheatstone Bridge to compare the resistances base on a temperature less than 60 degrees in order to compare it to. The primarily dilemma for this was time, writing the code, and connecting it to the control panel for power. Now I’m going to hand it over to Tyler from Energy

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Reflection (Class)

final presentations - talk about lessons learned and challenges faced

present results of retrospective in a formal way.

overall

- we all were so focused on trying to make our own stuff work before integration and making sure everything worked together

- after POCs we all got way better at articulating the nitty-gritty details

- utilization of outside resources!!! (machine shop, connections/relationship with other students and profs

- a comfortable environment was created throughout all of section 2 to share ideas

- good communication between team members

structure -

communications, budget problems, deciding as a team to do anything before starting, better way to determine how to upscale, figuring out different aspects of our design (temp/sea scale), accountability

comms -

communication and attendance was good until beginning of integration, subteam com. was good, extra pieces bought with budget, holding each other accountable became difficult towards end

energy -

biggest challenge was integration between teams was challenging due to lack of knowledge about other subteams,

-chris hates dogs