Build Your Own Automated Indoor Growing Box (AIGB)

In this manual we will discuss how to assemble the Automated Indoor Growing Box (AIGB) and how to operate it. An AIGB is a box where the environment can be controlled to optimize a plants growth. In this AIGB, six small plant can be grown by controling the temperature, humidity, light, waterflow, nutrions and CO2. This manual can either be used as a reference for different operations, for your own project, or to make this AIGB yourself.

We decided to convert a fridge into an Automated Indoor Growing Box. This makes sure the inside environment is stable. Also, the lights generate heat, so the cooling components from the fridge can be used to cool the environment.

Below a list with the supplies that have been used for this project. If you are more experienced with Raspberry Pi projects feel free to use different components.

• Raspberry Pi 4
• Flatcable Raspberry Pi
• XL4016-200w step down converter [2x]
• Waveshare 2 inch IPS-TFT-LCD
• Led-strip 5 V (1 m)
• BME280 Temp/humidity/pressure sensor
• MH-Z19C CO2 sensor
• dfrobot pH sensor
• dfrobot Conductivity sensor
• Fluid pump 12V [3x]
• Fluid pump 6V
• L298N Motor controller [2x]
• IBT-2 H-bridge
• Fluid tube 8mm x 1m
• Hose tube 10 mm x 50 cm
• Fridge 230 V AC
• AC-DC converter
• Waterreservoir (some kind of bucket or box)

For this project a custom made PCB was used (to be updated). Either this custom PCB can be used or a simple breadboard to connect all components.

Required expertise:

• Know how to make 3D-models using CAD-software
• Know how to 3D-print
• Know how to solder
• Knowledge of electronics
• Know how to use a Raspberry Pi 4
• Know basic Python programming

Needed machines/tools:

• 3D-printer
• Lasercutter
• Drilling machine
• Soldering iron
• Basic tools (screw driver, cutter, etc.)

Several 3D-prints were used to attach sensors and other components to the fridge. The files are attached to the corresponding steps.

First a few mechanical preperations have to take place, such as drilling holes in the fridge, lasercutting wood and 3D-printing other custom parts.

Drilling holes in the fridge

A few holes have to be drilled in the fridge for the air in -and outlet, the watergrid and for cables to run inside the fridge. The following holes were drilled (all dimensions are measured from the centre of the hole):

• Air outlet
• Diameter: 40 mm
• Location: Left side (70 mm from the top down / 70 mm from the front to back [excl. door])
• Air inlet
• Diameter: 15 mm (3x)
• Location: Back side (55 mm from the bottum up /110,125 and 140 mm from the left side of the fridge to the right)
• Watergrid
• Diameter: 30 mm
• Location: Bottom side (280 mm from the front to back [excl. door] / 130 mm from the left inside to the right)
• UPT cable
• Diameter: 16 mm
• Location: Back side (60 mm from the bottom to top / 60 mm from the left side of the fridge to the right)

Lasercutting wood

For the base underneath the fridge a few 6 mm panels have to be cut using the lasercutter. All DXF files can be found attached to this step.

3D-printing

The 3D-printed parts can be found attached to this step. For the watergrid it is recommended to use PETG instead of PLA. PETG will have a longer life span compared to PLA when used with water.

Before placing the electronics on the back of the AIGB, two wooden plates were first attached under the name "converter and H-brigde"and "Baseplate" these can both be found as .dxf files. The plates are attached with standard M3 wood screws. This does require a small 2.5mm hole to be pre-drilled and the metal back of the AIGB. The exact positioning is up to you. All electrical components are then fastened with M3 bolts and corresponding spacer bushings through the wood to the metal back which again needs to be pre-drilled.

To construct the electric hardware, the following parts will be needed:

Parts

• 1x Raspberry pi 4
• 2x XL4016-200w step down converter
• 2x L298N dc-motor controller
• 1x IBT-2 H-Bridge
• 1x 5v arduino relay
• 1x AIGB Raspberry Pi Shield
• 1x Raspberry pi Flatcable
• 1x 5A Fuse
• 1x 60-70cm cable tray
• 24x m2 3cm bolts
• 24x m2 spacers

There are two sensor boxes on the AIGB, one inside for air measurements and one underneath for measuring the water quality. The following parts will be needed:

Parts

• 1x MH-Z19C (co2)
• 1x BME280 (Temp, Hum, Pres)
• 1x dfrobot ph-sensor
• 1x dfrobot conductivity sensor
• 2x RJ45 female connector

Make sure all mechanical parts are secure. After that, connect all electronic components to the back of the fridge as shown in the pictures. Follow the electric scheme to see what goes where. If necesarry, extend the cables.

The video's attached to this step gives a good step by step guide on how to assemble the wooden box and attach it to the fridge. A few things to keep in mind:

• Sand all edges of the wood that will be glued together and make sure it is clear of dust.
• Make sure to dryfit the wooden parts before gluing them together.
• Make sure the bottom of the wooden box it positioned correctly! (The bottom can be flipped upside down and still fit with the other wooden parts. However, it will not fit on the fridge anymore.)
• The left side of the box consists of a wall and a door. In the video the door is already in place. Make sure to fix the door before connecting the wooden box to the fridge.

The smaller feet of the fridge can be used to level the fridge on the table.

You can consider to paint the box any color you like. We painted it black to match the color of the fridge and applied the AIGB logo on it.

To construct the air in- and outlet the following parts will be needed.

Parts

• 3x 12V fans (4cm x 4cm)
• Back inlet (3D print)
• Inside inlet (3D print)
• 2x Inlet cover (3D print)
• Outlet (3D print)
• Outlet cover (3D print)
• 12x m3 20mm bolts
• Back and red electrical wire
• Glue suitable for plastics

To construct the air flow system the following steps are recommended.

Air inlet

Step 4.1 First connect the two fans on the back inlet with the M3 bolts, make sure to add the inlet covers before screwing the fans on. Also, keep in mind that the label of the fans should be facing inwards for the correct airflow.

Step 4.2 Solder the wires from the two fans together to the black and red wires and extend them at least 20 cm.

Step 4.3 First insert the inside inlet through the slot from the inside of the box, then insert the back inlet with the fans connected through the same hole from the back. If the slot is small enough, the whole thing will already be tightly secured. If not, glue can be applied in the slot to secure everything.

Air outlet

Step 4.4 The third fan should be attached to the air outlet with the four remaining M3 bolts.

Step 4.5 Insert the assembly through the top most hole with the diameter of 4 cm.

Step 4.6 Glue the outlet cover on to the small part that pokes out the hole on the outside, make sure this part is orientated correctly before gluing it together.

To construct the watergrid, the following parts will be needed:

Parts

• 4x M5x30 bolt
• 4x M5 locknut
• 8 mm water tube with length of approx. 80 cm.
• 10 mm waterhose tube with length of approx. 50 cm.
• 60 mm PVC tube with a length of 220 mm.
• Left Pipe connection (3D print) [Consists of 2 parts]
• Right side pipe connections (3D print) [Consists of 2 parts]
• 6x water barier (3D print)
• 6x plant cup (3D print)
• Glue suitable for plastics (PVC-glue is recommended)

First drill out 2 holes of 40 mm in the PVC pipe, 60 mm from both sides. Then cut the panels (with the holes in them) out of the PVC tube. From the centre cut out a panel with a length of 190 mm and a width of 50 mm.

Before assembling the watergrid, keep in mind that:

• All parts that will be glued are sanded.
• Dryfit all parts before gluing.
• Put the watergrid in the fridge while gluing to make sure everything alligns propperly.
• When using PVC-glue make sure to glue it quickly as the glue will dry in a few seconds. (Because of our tight fit we chose to glue the parts after putting them together. We put a bunch of glue around the edges to make sure all parts were secured to eachother and to make sure everything was watertight.)

Follow the steps in the attached video to assemble the watergrid.

After the glue has dried, use water to test if the watergrid is watertight. Pour water in the top tube and but a bucket underneath the watergrid. Also, make sure no electronics are nearby!

The following steps should be taken to assemble the lighting:

1. Cut the LED-strip in half and lay them down next to eachother, where the ends of the LED-strip allign with eachother. Solder wires to the cutted parts of the LED-strip to solder them together (one end only).
2. Testfit the Ledstrip on the inside top of the frigde, 90 mm from the front to back. Make sure everything is able to allign propperly and that the cable is on the left side.
3. Pull off the plastic from the tape and stick it to the fridge.

Check all mechanical components by making sure they are all secured properly.

Connect the system to a 24V power source. Make sure the system is connected through a 5A fuse to make sure the system doesn't overload. Check if all electronic components work propperly by using a multimeter.

The AIGB can be controlled with two different interfaces. A dashboard accessible via the Internet and a physical HMI in the form of an LCD screen with buttons. The following features are the same for both components:

• Air temperature
• Humidity
• CO2 levels
• Water conductvitie levels
• pH level

The LCD

As of now, the LCD screen only indicates the values recovered by all the sensors. The goal is to also give a clear indication of what actions the AIGB is currently working on. Next to the LCD screen, there will be one button available to scroll through different screens of the AIGB.

The dashboard

The online dashboard was created in Cayenne. On the left side, we see the current default values of temperature, humidity, etc. There are several additional features on the dashboard, such as an extended graph of the values of last period (see the second column). Also, the dashboard shows which actuators are already active and it has a screen where you can manually control the actuators. As shown in the picture on the right, where the light intensity can be adjusted.

The software for the AIGB consists of 4 parts:

• Sensor reading
• Actuator control
• Online dashboard connection
• LCD screen control

All software runs on a Raspberry pi 4, which can be controlled with Python. Further explanation on how to set up the software can be read in the README file on GitHub (link below).

https://github.com/bwni/Project_AIGB

This project has been successfully completed. It is the basis for setting up an AIGB and can be used as a lecture subject. One can use this product to read all the sensors and control the actuators. Extensions to the controller area can now be filled in by oneself. To make the system autonomous.