A robot that follows things.

The bot has three ultrasonic rangefinders on the front, one pointing forward, one to the left and one to the right, if something comes in the way of the rangefinders the robot moves towards it.

The following logic:

• If the forward sensor sees something go forward.
• If the left sensor sees something turn left.
• If the right sensor sees something turn right.
• If none of the sensors see anything stop.

In the code I made the bot ignore things that are further away than 20 centimeters as well as things that are closer than 6 centimeters, so if the bot drives up to a wall or up to you it stops when it gets close and if something is far away from it then it doesn't go to it.

Using the code

You will need the Arduino IDE to upload the code to your Arduino.

• Clone or download this repo.
• Open the following_robot.ino file in the Arduino IDE.
• Select your board from tools>board.
• Upload the code to the board by pressing the Upload button, it's the arrow in a circle, at the top left corner of the IDE.

Building the robot

Parts:

• An Arduino.
• 3 ultrasonic rangefinders, I used the HC-SR04.
• A motor driver, I used an L293D.
• 2 DC motors.
• 2 wheels.
• A caster.
• A robot chassis.
• Some standoffs to mount the Arduino and motor driver(optional, you can just tape them on to the chassis).
• Cardboard, to mount the three sensors to the front of the robot.
• Tape

Bend a cardboard strip in three places, and tape the sensors to it. Then tape that to the front of the chassis, like this:

Then mount the Arduino and motor driver to the chassis with standoffs, or just tape them onto it, if you have a metal chassis put a sheet of paper or something under the Arduino and motor driver so they don't short out on the chassis.

Wiring

Arduino	HC-SR04 rangefinders
Digital pin12	Left sensor Echo
Digital pin11	Middle sensor Echo
Digital pin10	Right sensor Echo
Digital pin9	Left sensor Trigger
Digital pin8	Middle sensor Trigger
Digital pin7	Right sensor Trigger
GND	GND
5 volts	PWR

Arduino	L293D motor driver
Digital pin2	Left motor pin1
Digital pin3	Left motor pin2
Digital pin4	Right motor pin1
Digital pin9	Right motor pin2

Diagram:

Licensing:

All the photos and diagrams for this project are under the Creative Commons Attribution-ShareAlike 4.0 International License.
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

All the code is under the MIT license: http://mit-license.org/