Growing Beyond Earth Lettuce Box - Poly Engineering Club

Hello! Our Engineering Club decided to participate in the Growing Beyond Earth Maker Contest. We sought to challenge ourselves to maximize the space within a box in zero gravity. Over the course of a couple weeks, we brainstormed many designs and ideas until we settled on this! We call it the "Lettuce Box." :)

Arduino Mega, UV Lights, Arduino LCD Display, lexan sheet 494mmx494mmx6mm, Grow fabric, Raindrip tubing, Tubing, Soil Sensor, 10L water bag, Relay, Temp sensor, Pump, Screws, Jumper Wires, connectors

https://docs.google.com/spreadsheets/d/1YwrFfN71KIX2LLPhPQXeafIknFsYu-KOUywy6P3P1UQ/edit?usp=sharing

We went through multiple revisions throughout the design process. We strove to make the design as simple and light as possible. At school, we have access to 3D printers, so we created the top and bottom plant trays out of PLA. Unfortunately we had to print them in multiple stages due to the limited size of the printers. Afterwards, we glued the sections together to make the two complete trays.

To suspend the lights above the lettuce, we created a mount to hold PVC tubes that run across the entirety of the plant tray. We also printed out the mounts and mounted them to the poly-carbonate with M3 bolts.

The UV Lights, Arduino LCD Display, Soil Sensor, Relays, Temperature and humidity sensor, and Pump are connected to, controlled by, and powered through the Arduino Mega. The relays switch the pump and UV lights on and off. The soil sensors detect the moisture level of the soil and the temperature and humidity sensor detects the temperature and humidity inside the Lettuce Box. The LCD Display displays the data collected by these sensors.

The code is separated into the following sections: Timer, Pump Relay, Grow Light LED Relay, Temperature and Humidity Sensor, Soil Sensors (1 and 2), LCD Screen. Each section (except for the timer) pertains to one of the physical electronics components present in the Lettuce Box. The timer runs on the Arduino millisecond internal clock, updating every second. The pump and grow light LED are switched on and off with relays based on the aforementioned 24 hour timer. The temperature and humidity sensor and the the soil sensors record data on the conditions of the Lettuce Box. The LCD screen then displays all of this data in four slides that alternate every four seconds. In order to have the timer consistently update on the screen, we had to duplicate each slide four times so that a new time is displayed every second. Download the required dht and LCD libraries to your computer from the following websites:

LCD Screen: http://wiki.sunfounder.cc/index.php?title=I2C_LCD2...

DHT: https://www.brainy-bits.com/dht11-tutorial/

If you couldn't download the code from this, use the link:

Code: https://drive.google.com/file/d/1fFrhdX883voQAndZk...

Within our 3D printed walls, we have soil that is placed above our irrigation system, on the top and bottom. The plants grow towards the center, to maximize space. The soil is covered with tarp to prevent it from leaving in a gravity free environment. The irrigation system starts with a water bag hooked on the wall. Next, the pump pushes the nutrient rich water through the pipes to our permeable hose under the soil. With enough pressure in the permeable pipes, water is able to leak out and irrigate the soil. In the center of the box, there is two pvc pipes with LED grow lights to imitate sunlight for the plants. With our setup, we should be able to grow 9 heads of lettuce on each side, totaling to 18.