『EP1000 DIGI FABLAB』

Fabrication

Once the design is done, I convert the parts to its appropriate files to prepare for fabrication.

Laser cutting

The Tower and Servo holder are to be cut with the laser cutter, so I convert the part faces into a dxf file. I then use LibreCAD to check the outlines are correct. I also compiled all the parts into a single file.

Using 3mm clear acrylic for the Servo support and 3mm white acrylic for the Tower

3D printing

The spouts and servo horn require 3D printing to fabricate. I first convert the file to STL

I require 3 spouts, but becuase I printed 1 for testing here I only need 2.

Ultimaker Cura Print settings:

• Layer height = 0.2mm
• Infill: Density = 15%, Infill pattern = Grid
• Print speed = 90mm/s
• No support generation
• No build plate adhesion

Completed prints:

Spout.stl | Horn.stl

Assembly

The parts were a loose fit, so I used some chloroform to fix them together. Here I only connected the slider guard and 3 of the wall panels together, so I can still fix in the interior later.

Assembled piece:

As the Servo wire was in the way, I ended up fixing the servo on from the underside of the acrylic support,

To attach the printed servo horn I simply used a screw to secure it. To secure the tube in place I used a thin wire. As the Servo can only rotate 180 degrees, I positioned the horn to face the leftmost spout opening so it can reach the other 2.

Electronics

Next is programming and integrating the electronics into the build.
The idea is to direct the servo towards the pot that is detected dry, and turns on the DC motor to pump water until no longer dry.

I first prototype and program the circuit on ThinkerCAD.

As ThinkerCAD does not have a water sensor, I used an LDR as replacement as both sensors are analog and works similarly.

I start with the output devices, which are the Servo and DC motor pump.

Testing the Servo: I programmed it such that the servo would rotate in specific angles to aim the tubing to the correct spout.

In order to interface the DC motor to the Arduino I require a transistor to run it. For this I used a 2N2222 transistor. The transistor is connected to analog pin 9.

I wrote a program to test the servo and motor to position and dispense water.

For the input devices, I will need a water sensor to detect amount of water in soil. I connected the sensor as an analog input so it can measure moisture percentage.

For testing I only connected 1 water sensor, while the other ports are shorted.

Arduino program code:

//water sensor
const int h1 = A0; //Plant One sensor 
const int h2 = A1; //Plant Two sensor 
const int h3 = A2; //Plant Three sensor
int value1; //h1 value
int value2; //h2 value
int value3; //h3 value

//servo
#include <Servo.h>
Servo servo1;
int pot1 = 0;
int pot2 = 90;
int pot3 = 180;

//motor pump
#define motor_pin 9

bool action = 0; 

void setup()
{
  Serial.begin(9600);
  Serial.println("ready");
  
  //servo
  servo1.attach(5);
  servo1.write(pot1);
  
  //motor
  pinMode(motor_pin, OUTPUT);
  
}

void loop()
{
  //read water sensor
  value1 = analogRead(h1);
  value2 = analogRead(h2);  
  value3 = analogRead(h3);  
    
  value1 = constrain(value1,400,1023);
  value2 = constrain(value2,400,1023);
  value3 = constrain(value3,400,1023); 
   
  value1 = map(value1,400,1023,100,0);
  value2 = map(value2,400,1023,100,0);
  value3 = map(value3,400,1023,100,0);  
  
  Serial.print("h1=");
  Serial.print(value1 );
  Serial.print(" h2=");
  Serial.print(value2 );
  Serial.print(" h3=");
  Serial.println(value3 );
  delay(1000);
  
  //pot1
  if (value1 <= 30){ //pot detect dry
    if (action == 0){
      action = !action;
      servo1.write(pot1);
      delay (3000);
      digitalWrite(motor_pin, HIGH);
      delay(4000);
      digitalWrite(motor_pin, LOW);
      delay (2000);
      action = !action;

    }
  }

   //pot2
  if (value2 <= 30){ //pot detect dry
    if (action == 0){
      action = !action;
      servo1.write(pot2);
      delay (3000);
      digitalWrite(motor_pin, HIGH);
      delay(4000);
      digitalWrite(motor_pin, LOW);
      delay (2000);
      action = !action;
        
    }
  }
   //pot3
  if (value3 <= 30){ //pot detect dry
    if (action == 0){
      action = !action;
      servo1.write(pot3);
      delay (3000);
      digitalWrite(motor_pin, HIGH);
      delay(4000);
      digitalWrite(motor_pin, LOW);
      delay (2000);
      action = !action;

    }
  }
}

How the program works:

• The water sensors are read as analog inputs, which the readings are shown as moisture percentage.
• When the water sensor detects moisture level is below 30, the Boolean "action" will become 1, which will prevent other actions from happening while it attends to the pot first detected.
• The Servo will then rotate to a specific angle, which positions the tube to the correct spout.
• The motor pump will then be turned on to dispense water, and turned off after 4 seconds.
• "Action" will go back to 0. indicating the action is completed.
• The program will go back to reading the water sensors.

After ensuring the I/O components work, I transfer the circuit onto an Arduino nano so it can fit into the compartment.

Documentation

Hero shots:

Setting up the Plant Fountain:

1. Place potted plants under the spouts.
   
2. Insert water sensors into soil.
   
3. Place pump into container, fill with water.
   
4. Plug Arduino into power source.
   
5. Refill water container when needed.

Video

Presentation

Review

In all, the Plant Fountain works as intended, but more improvements can be done to make it better.

Some improvements and additions that can be done:

• A function to disable water delivery to specific spouts (if system is not required to maintain all pot stations).
• Spout modification to prevent water puddles from staying on the spout.
• A built in water compartment so an external bottle would not be needed.
• Built in Grow Lights so plants can grow at night or in dark places.