Indoor Agriculture Part 2 - Ultrasonic Fogger on an interval

This second installment on Indoor Agriculture focuses on building an Ultrasonic Fogger system which runs on a schedule. Once again, we will use an Arduino Uno to run a relay, and use a Raspberry Pi Zero W to manage cycles via serial connection.

Additionally, it deals with creating a CAD model of the machine we’re prototyping. The Ultrasonic Fogger needs to be submerged so we might as well design a nice reservoir.

Bill of Materials

Constructing the Circuit

Build the circuit as illustrated by the following diagram.

Initially I tried using just the ultrasonic transducer but it turns out that they need to be driven. Who knew? I switched to using a garden decoration fogger which takes an external power source. These can’t be driven 24/7 so we will need to turn it off for a period of time. Good thing we bought a 2-channel relay.

NOTE: Don’t run this without having the ultrasonic fogger submerged.

CAD modelling the machine

Lets take this opportunity to create a CAD model of the machine. We need a way to mount the LED lights, an electronics enclosure, and water reservoir. I took me several iterations create a model which could minimize the cost of 3d printing. I had to minimize surface area and max component dimensions.

Test the Circuit

1. Clone the following git repository: Indoor Agriculture
2. Upload the ultrasonic_fogger.ino program onto the Arduino Uno.
3. Follow the README.md instructions to setup the python software on the Raspberry Pi Zero W.
4. Run the ultrasonic_fogger.py program
5. Send 2 to turn the ultrasonic fogger off
6. Send 3 to turn the ultrasonic fogger on

Setup the Day/Night and Mist/Dry schedule

1. Configure the ULTRASONIC_FOGGER_ON_MINUTES, ULTRASONIC_FOGGER_OFF_MINUTES, variables in the .env file.
2. Run the ultrasonic_fogger_schedule.py program.

Next steps

Alright, done. It took awhile because I didn’t designed the machine first and inadequately researched interfacing the ultrasonic fogger. Next, I need to:

1. Manufacture the Light Arm.
2. Build a ROS system to manage the hardware a high level.
3. Start growing garden herbs.

Stay tuned for part 3.

Written by Peter Chau, a Canadian Software Engineer building AIs, APIs, UIs, and robots.