Obstacle Avoidance Robot with HC-SR04 and Raspberry Pi — Part 14: Stop Before You Crash

New here? This part adds an HC-SR04 ultrasonic sensor to the C101 robot from Part 13 — the car now stops, backs up, and steers around obstacles automatically. The wiring builds on the Raspberry Pi + L298N setup from Part 13. If the GPIO connections feel unfamiliar, a quick skim of Part 13 will help. Otherwise, let’s go.

Raspberry Pi 4WD Robot Car with Python and L298N — Part 13: Four Wheels, One Brain

New here? This part covers wiring the C101 4WD kit to a Raspberry Pi 3B via L298N and writing Python directly on the Pi to drive the car — no laptop, no USB cable, no Arduino middleman.

Raspberry Pi 3B Setup for Robotics — Part 12: The Robot Gets Its Own Brain

Let's address the obvious problem.

A robot that needs a laptop sitting next to it isn't really a robot. It's a very expensive remote control. Even the thinnest laptop on the market — say, an Asus Zenbook A14 — weighs over 2.5 lbs and measures 13×9 inches. That's not riding inside a robot. That's the robot riding inside a carry-on bag.

HC-SR04 Ultrasonic Sensor with Arduino and Python — Part 11: Meet the Real Sensor

Phase 1 was a scenic tour through the world of robotics — high mileage, low spending, maximum borrowing from things we already owned. Laptop, old phone, RC car from the garage, a few skipped Starbucks runs. Ten parts, under $40, and a surprisingly complete picture of how robots actually think.

Beginner Robotics with Python: Phase 1 Recap — Part 10: What We Built, What We Learned

Nine parts. Less than $40 total. A few skipped Starbucks runs, a few sacrificed Taco Bell Crunchy Tacos — all in the name of science, and the deeply held belief that somewhere down this road, we build something better than Bumblebee. Or at least Bumblebee’s budget cousin.

Line Following Robot Simulation with Webcam and OpenCV — Part 9: The Robot Learns to Stay in Its Lane

Of all the senses a robot can have, vision gets the most attention. Always has. Probably always will.

Face Recognition Attendance System with Python and OpenCV — Part 8B: The Robot Knows Who You Are

Quick recap before we dive in.

In Part 8A, we built Face Detection: the robot learned to find faces in a live video stream and draw a green box around them. It could answer "Is there a face here, and where is it?" — nothing more.