Engineering For The Community

certification-marks-for-iot-devices-a-su

SUMMARY:

For my spring 2020 semester at CU Boulder, I worked with a group of 4 other engineers on a design project meant to help a small business in the Boulder community. For our project, we needed to figure out a way fully automate the refilling of two 4400 gallon water tanks that draw water from a nearby spring and provide water to a local farm.

To achieve this, we designed and built an IoT device using a pressure transducer connected directly to an easily accessible water pipe and a Wifi-enabled micro-controller (the Particle Photon). The Photon reads the pressure data, performs statistical analysis, and communicates with another Photon whether or not to turn the pump on. We also provided an override on and off function that can be controlled directly from a smartphone app for days when the pump needs to be continuously kept on.

CLIENT:

Our client was Andre Houssney, the owner of Jacob Springs Farm in Boulder, Colorado. Jacob Springs is a diversified, beyond organic, local farm that specializes in grass-fed lamb, duck, chicken, goose and eggs as well as various fruits, herbs and vegetables. Mr. Houssney works incredibly hard every day to run his farm, so having to constantly remember to turn his pump on and off was a pain. By automating this process, he will have peace of mind that he will always have the needed amount of water to run his farm, and the ability to take manual control of his pump any time he wants directly from his smartphone, even when he is away from his house.

DESIGN REQUIREMENTS:

Permanent fixture in humid environment
Accurate pressure readings
Automatically turn water pump ON/OFF when tanks are nearly empty and nearly full.
Minimize number of times pump is turned ON/OFF
Override functions through Particle.io phone app
Communicate with other devices on Particle Cloud

FINAL DESIGN

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PHYSICAL DESIGN:

Physically, our design is completely waterproof, including the wire glands. While we could have included wire glands, an O-ring, and other waterproofing material using our 3D-printed design, due to COVID-19, our access to 3D printers and other prototyping equipment was cut off, leaving purchasing an Adafruit enclosure the next best option.

We also included an LCD display so the data could be monitored manually. Given more time we would include buttons and/or knobs and use the LCD screen as a GUI.

PERSONAL CONTRIBUTION:

I contributed a considerable amount to the initial prototyping stages of the physical product. I played an integral role in the decision- making process, though the CAD designs and assembly were done by other group members.

ELECTRICAL DESIGN:

The electrical deign includes three main features:

A standard 0.1uF decoupling capacitor was used to reduce noise from our power brick that was plugged into a wall outlet.

An RC circuit allowed us to filter out our analog data noise with a maximum length of 30 seconds. This number was used as an approximation of time of the high frequency noise in our data.

A voltage divider was used to step down our analog data from the 4.5V logic of the pressure transducer to the 3.3V logic of the Photon micro-controller.

PERSONAL CONTRIBUTION:

I was the primary contributor to the electrical design process. The eCAD design and PCB are my work. The electrical component values were informed by data analysis provided primarily by other group members with help from Mr. Houssney.

PROGRAM DESIGN:

The program is designed using a moving average to smooth over noise in our data caused by constant changes in water pressure from normal water use such as turning on a sink. Data taken that is outside 1.3 standard deviations below or 3 standard deviations above our moving average is ignored to filter out longer periods of noise when the pipes empty.

Max high and low pressure values were set with large safety nets to ensure the tanks are never empty and never full, and to make sure the pump turns ON/OFF as infrequently as possible to extend the pump's usable life.

PERSONAL CONTRIBUTION:

I was the primary contributor to the programming process. Some programming design decisions were informed by group members, teachers, and Mr. Houssney.

PRODUCT TESTING:

When the product is complete and the semester ends, we will keep in touch with Mr. Houssney in order to conduct further statistical analysis and make adjustments to the program (which can be remotely updated over the Particle Cloud). We will be in contact with Mr. Houssney for the next few months to make sure his device continues to work during the changing seasons.

CONCLUSION:

I learned a ton during this process. On the engineering skills side, I learned how to use the eCAD software, Autodesk Eagle, to make clear and readable circuits and to design a custom PCBs from my circuit designs. I also extended my knowledge of Arduino programming to include the Particle.io Web IDE, Particle Cloud Console, Desktop Workbench, and Particle language primitives. I am now confident in my IoT device design skills, and I would love to work on a similar project in the future.

On the team and leadership end, I learned that above all else, proper communication is paramount to a functional engineering team. In future projects, I will definitely use organizational software such as Trello and Github so every member of the team can be fully informed of their responsibilities at all times and always have access to the latest files. A well organized team is a motivated team.

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