Building a Two-Wheel Drive Robot

Assemble a simple two-wheeled robot chassis using motors, sensors, and the Raspberry Pi Pico.

Now that you’ve mastered motor and sensor control, it’s time to build your robot! In this lesson, we’ll assemble a two-wheel drive robot chassis that will act as the base for the remaining lessons.

🧱 Components You’ll Need

• Chassis kit (with mounting holes for motors and wheels)
• 2x DC gear motors
• 2x Wheels
• Caster wheel (or ball bearing support)
• L298N motor driver
• Raspberry Pi Pico
• IR line sensors (x2)
• Ultrasonic sensor (HC-SR04)
• Power supply (e.g. 4xAA battery pack or 2S Li-ion)
• Jumper wires / breadboard / Dupont cables
• Screws, nuts, double-sided tape or hot glue

🛠️ Assembly Instructions

1. Attach Motors to the Chassis
   Secure each DC motor to the motor mounts on your chassis. Make sure both motor shafts face the same direction.

2. Connect the Wheels
   Push the wheels onto the motor shafts. Add a caster wheel or similar support at the back or front for balance.

3. Mount the L298N and Pico
   Use double-sided tape or standoffs to fix the L298N and Raspberry Pi Pico to the chassis.

4. Wire the Motors
   Connect both motors to the L298N outputs (OUT1–OUT4), then wire the control pins to the Pico as described in previous lessons.

5. Add Sensors
   • Mount the IR sensors near the front underside, facing the ground.
   • Mount the ultrasonic sensor at the front facing forward. Optionally attach it to a servo.
6. Power Up
   Connect your battery pack:
   • Battery + → L298N VCC
   • Battery – → L298N GND
   • Pico GND → L298N GND
   • Power the Pico separately via USB or from L298N 5V pin (if jumper is present and you’re using 6V–12V input).

⚠️ Double-check polarity before powering on!

🎛️ Testing the Setup

Run the motor control and sensor code from previous lessons to verify:

• Motors spin in the correct direction
• IR sensors detect a line
• Ultrasonic sensor reports distance

Make adjustments to wheel orientation or wiring as needed.

🧩 Try It Yourself

• Experiment with motor speed and turning radius.
• Reposition sensors for better detection.
• Add a power switch or LED indicator.

You now have a complete robot chassis ready for autonomous or remote-controlled behavior!

Next up: Servo Scanning with Ultrasonic Sensors

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