Obstacle-Avoiding Robot with Raspberry Pi

This is the classic first robot: two motor channels, one distance sensor and a simple decision loop. It teaches motors, sensors, power and code all at once.

Video tutorial

▶ RobojaxWatch on YouTube ↗

Video by Robojax, embedded from YouTube. The written steps below are our own and match the parts list.

Mission steps

1. Build the chassis

   Assemble the kit, pair the left motors and right motors together and route the wires to the top plate.

2. Wire the motor driver

   TB6612FNG: AIN1/AIN2/PWMA to GPIO5/6/12, BIN1/BIN2/PWMB to GPIO13/19/26, STBY to GPIO25. Motor power (VM) from the battery; logic (VCC) from 3V3.

3. Wire the sensor safely

   HC-SR04 runs on 5 V and its ECHO pin outputs 5 V. Use a voltage divider (1 kΩ + 2 kΩ) on ECHO before it reaches GPIO24. TRIG goes to GPIO23.

4. Power

   Run the Pi from a 5 V 3 A UBEC fed by the 18650 pack. Join all grounds.

5. Run the code

   The loop drives forward until something is closer than 25 cm, then backs up and turns.

Code

from gpiozero import Robot, Motor, DistanceSensor, OutputDevice
from time import sleep

OutputDevice(25).on()                      # TB6612 standby off
bot = Robot(left=Motor(5, 6, enable=12), right=Motor(13, 19, enable=26))
eye = DistanceSensor(echo=24, trigger=23, max_distance=2)

while True:
    if eye.distance < 0.25:
        bot.backward(0.5); sleep(0.4)
        bot.right(0.6);    sleep(0.5)
    else:
        bot.forward(0.6)
    sleep(0.05)

Tip: test every script on the bench before installing it in a moving machine.

Questions