How to Build a Robot at Home

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Last Updated: April 20, 2024 Fact Checked

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Do you want to learn how to build your own robot? There are a lot of different types of robots that you can make by yourself. Most people want to see a robot perform the simple tasks of moving from point A to point B. You can make a robot completely from analog components or buy a starter kit from scratch! Building your own robot is a great way to teach yourself both electronics as well as computer programming.

Part 1

Part 1 of 6:

Assembling the Robot

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1
Gather your components. To build a basic robot, you'll need several simple components. You can find most, if not all, of these components at your local electronics hobby shop, or several online retailers. In fact, some basic kits may include all of these components as well. This robot does not require any soldering:
- Arduino Uno (or other microcontroller)^{[1]
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- 2 continuous rotation servos
- 2 wheels that fit the servos
- 1 caster roller
- 1 small solderless breadboard (look for a breadboard that has two positive and negative lines on each side)
- 1 distance sensor (with four-pin connector cable)
- 1 mini push-button switch
- 1 10kΩ resistor
- 1 USB A to B cable
- 1 set of breakaway headers
- 1 6 x AA battery holder with 9V DC power jack
- 1 pack of jumper wires or 22-gauge hook-up wire
- Strong double-sided tape or hot glue
You'll be building the robot's body using the battery pack as a base.

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This should be the end that the battery pack's wire is coming out of The servos should be touching bottoms, and the rotating mechanisms of each should be facing out the sides of the battery pack. The servos must be properly aligned so that the wheels go straight. The wires for the servos should be coming off the back of the battery pack.
4
Affix the servos with your tape or glue.^{[2]
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Research source} Make sure that they are solidly attached to the battery pack. The backs of the servos should be aligned flush with the back of the battery pack.
- The servos should now be taking up the back half of the battery pack.
It should hang over the front of the battery pack just a little bit and will extend beyond each side. Make sure that it is securely fastened before proceeding. The "A" row should be closest to the servos.
If you attached the servos properly, there should be a flat space made by them touching. Stick the Arduino board onto this flat space so that the Arduino's USB and Power connectors are facing the back (away from the breadboard). The front of the Arduino should be just barely overlapping the breadboard.
Firmly press the wheels onto the rotating mechanism of the servo. This may require a significant amount of force, as the wheels are designed to fit as tightly as possible for the best traction.
8
Attach the caster to the bottom of the breadboard. If you flip the chassis over, you should see a bit of breadboard extending past the battery pack. Attach the caster to this extended piece, using risers if necessary. The caster acts as the front wheel, allowing the robot to easily turn in any direction.^{[3]
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- If you bought a kit, the caster may have come with a few risers that you can use to ensure the caster reaches the ground. i

Part 2

Part 2 of 6:

Wiring the Robot

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You'll be using these to connect the servos to the breadboard. Push the pins down through the header so that the pins come out at an equal distance on both sides.
Make sure that they are firmly inserted.^{[4]
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This will connect the servos to the breadboard. Make sure the left servo is connected to the left header and the right servo to the right header.
Make sure you use the red rail on the back of the breadboard (closer to the rest of the chassis).
Make sure that you use the blue rail on the back of the breadboard. Do not plug them into the red rail pins.
This will allow the Arduino to control the servos and turn the wheels.
It does not get plugged into the outer power rails on the breadboard, but instead into the first row of lettered pins (J). Make sure you place it in the exact center, with an equal number of pins available on each side.
This will ground the sensor.
This will power the sensor.
This will feed information from the sensor to the microcontroller.

Part 3

Part 3 of 6:

Wiring the Power

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Orient it so that the battery pack cable is coming out to the left at the bottom.
Make sure that the battery pack is oriented correctly.
These two cables will help provide the correct voltage to the Arduino.
The black cable should be plugged into the blue rail pin at pin 30. The red cable should be plugged into the red rail pin at pin 30.
Connect it at pin 28 on the blue rail.
Do not connect the red rails, as you will likely damage the Arduino.
This will provide power to the Arduino.
This switch will allow you to turn off the robot without having to unplug the power.
This will power the button.
Connect it to the pin directly next to the black wire that you connected a few steps ago.
This will allow the Arduino to register the push button.

Part 4

Part 4 of 6:

Installing the Arduino Software

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This is the Arduino development environment and allows you to program instructions that you can then upload to your Arduino microcontroller. You can download it for free from arduino.cc/en/main/software. Unzip the downloaded file by double-clicking it and move the folder inside to an easy to access location. You won't be actually installing the program. Instead, you'll just run it from the extracted folder by double-clicking arduino.exe.^{[5]
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Plug the battery back jack into the connector on the Arduino to give it power.
Windows will likely not recognize the device.
⊞ Win+R and type devmgmt.msc. This will launch the Device Manager.
If you don't see this option, click "Properties" instead, select the "Driver" tab, and then click "Update Driver."
This will allow you to select the driver that came with the Arduino IDE.
You'll find a "drivers" folder inside.
Confirm that you want to proceed if you're warned about unknown software.

Part 5

Part 5 of 6:

Programming the Robot

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You'll be greeted with a blank project.
2
Paste the following code to make your robot go straight. The code below will make your Arduino continuously move forward.
```
#include <Servo.h> // this adds the "Servo" library to the program

// the following creates two servo objects
Servo leftMotor;
Servo rightMotor;

void setup()
{
    leftMotor.attach(12); // if you accidentally switched up the pins for your servos, you can swap the numbers here
    rightMotor.attach(13);
}


void loop()
{
    leftMotor.write(180); // with continuous rotation, 180 tells the servo to move at full speed "forward."
    rightMotor. write(0); // if both of these are at 180, the robot will go in a circle because the servos are flipped. "0," tells it to move full speed "backward."
}
```
3
Build and upload the program. Click the right arrow button in the upper-left corner to build and upload the program to the connected Arduino.
- You may want to lift the robot off of the surface, as it will just continue to move forward once the program is uploaded.
4
Add the kill switch functionality. Add the following code to the "void loop()" section of your code to enable the kill switch, above the "write()" functions.
```
if(digitalRead(2) == HIGH) // this registers when the button is pressed on pin 2 of the Arduino
{
    while(1)
    {
        leftMotor.write(90); // "90" is neutral position for the servos, which tells them to stop turning
        rightMotor.write(90);
    }
}
```
5
Upload and test your code. With the kill switch code added, you can upload and test the robot. It should continue to drive forward until you press the switch, at which point it will stop moving. The full code should look like this:
```
#include <Servo.h>

// the following creates two servo objects
Servo leftMotor;
Servo rightMotor;

void setup()
{
    leftMotor.attach(12); 
    rightMotor.attach(13);
}


void loop()
{
    if(digitalRead(2) == HIGH) 
    {
        while(1)
        {
            leftMotor.write(90); 
            rightMotor.write(90);
        }
    }

    leftMotor.write(180); 
    rightMotor.write(0); 
}
```

Part 6

Part 6 of 6:

Example

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1

Follow an example. The following code will use the sensor attached to the robot to make it turn to the left whenever it encounters an obstacle. See the comments in the code for details about what each part does. The code below is the entire program.

#include <Servo.h>

Servo leftMotor;
Servo rightMotor;

const int serialPeriod = 250;       // this limits output to the console to once every 1/4 second
unsigned long timeSerialDelay = 0;

const int loopPeriod = 20;          // this sets how often the sensor takes a reading to 20ms, which is a frequency of 50Hz
unsigned long timeLoopDelay   = 0;

// this assigns the TRIG and ECHO functions to the pins on the Arduino. Make adjustments to the numbers here if you connected differently
const int ultrasonic2TrigPin = 8;
const int ultrasonic2EchoPin = 9;

int ultrasonic2Distance;
int ultrasonic2Duration;

// this defines the two possible states for the robot: driving forward or turning left
#define DRIVE_FORWARD     0
#define TURN_LEFT         1

int state = DRIVE_FORWARD; // 0 = drive forward (DEFAULT), 1 = turn left

void setup()
{
    Serial.begin(9600);
  
    // these sensor pin configurations
    pinMode(ultrasonic2TrigPin, OUTPUT);
    pinMode(ultrasonic2EchoPin, INPUT);
    
    // this assigns the motors to the Arduino pins
    leftMotor.attach(12);
    rightMotor.attach(13);
}


void loop()
{
    if(digitalRead(2) == HIGH) // this detects the kill switch
    {
        while(1)
        {
            leftMotor.write(90);
            rightMotor.write(90);
        }
    }

    debugOutput(); // this prints debugging messages to the serial console
    
    if(millis() - timeLoopDelay >= loopPeriod)
    {
        readUltrasonicSensors(); // this instructs the sensor to read and store the measured distances
        
        stateMachine();
        
        timeLoopDelay = millis();
    }
}


void stateMachine()
{
    if(state == DRIVE_FORWARD) // if no obstacles detected
    {
        if(ultrasonic2Distance > 6 || ultrasonic2Distance < 0) // if there's nothing in front of the robot. ultrasonicDistance will be negative for some ultrasonics if there is no obstacle
        {
            // drive forward
            rightMotor.write(180);
            leftMotor.write(0);
        }
        else //  if there's an object in front of us
        {
            state = TURN_LEFT;
        }
    }
    else if(state == TURN_LEFT) // if an obstacle is detected, turn left
    {
        unsigned long timeToTurnLeft = 500; // it takes around .5 seconds to turn 90 degrees. You may need to adjust this if your wheels are a different size than the example
        
        unsigned long turnStartTime = millis(); // save the time that we started turning

        while((millis()-turnStartTime) < timeToTurnLeft) // stay in this loop until timeToTurnLeft has elapsed
        {
            // turn left, remember that when both are set to "180" it will turn.
            rightMotor.write(180);
            leftMotor.write(180);
        }
        
        state = DRIVE_FORWARD;
    }
}


void readUltrasonicSensors()
{
    // this is for ultrasonic 2. You may need to change these commands if you use a different sensor.
    digitalWrite(ultrasonic2TrigPin, HIGH);
    delayMicroseconds(10);                  // keeps the trig pin high for at least 10 microseconds
    digitalWrite(ultrasonic2TrigPin, LOW);
    
    ultrasonic2Duration = pulseIn(ultrasonic2EchoPin, HIGH);
    ultrasonic2Distance = (ultrasonic2Duration/2)/29;
}

// the following is for debugging errors in the console.
void debugOutput()
{
    if((millis() - timeSerialDelay) > serialPeriod)
    {
        Serial.print("ultrasonic2Distance: ");
        Serial.print(ultrasonic2Distance);
        Serial.print("cm");
        Serial.println();
        
        timeSerialDelay = millis();
    }
}

Community Q&A

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Question

How much time will it take to build a robot?

Community Answer

This depends on the complexity of the robot. You could build a simple robot in as little as a day. A more complex robot could take several several months.

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Question

What is the device called that you need to move robotic hands, arms and legs?

Community Answer

Servos (servomotors) are usually used to move robotic arms. Regular servos have a limited circulation.

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Why do I need to download the Arduino software?

Community Answer

Arduino code is very simplified and based off of C++. Other micro controllers are also available that use other software.

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Attach 2 toothbrush heads to the base of your robot if you want it to sweep the floor.

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If you want to add more character to your robot, cut out eye, arms, and legs out of paper, then attach them with tape.
Make sure to measure each part before buying so you don't have to return anything!

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