Robotics / Ultrasonic + Servo

Obstacle-Avoiding Bot

Combine motion, sensing, and directional scanning to build a small rover that can decide where to turn next.

Advanced 49 min By Admin Chileshe

What you will learn

  • Upgrade the rover into a patrol bot that pauses and reports blocked paths.
  • Use the same scan logic for an automated parking distance guide.

Components

3

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Build an Obstacle Avoiding Rover with Servo Sweep

CircuitSpark Lab • 27.8K views • Jan 21, 2026

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Advanced 49 min Robotics Admin Mentor: Admin Chileshe
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Build Guide

Step-by-Step Instructions

Step 1 of 3
1

Step 1

Mount the ultrasonic sensor on the servo

Secure the ultrasonic sensor so the servo can sweep it left and right without wobble. Loose mounts create false distance readings and inconsistent turns.

Keep cables clear of the wheels before you start writing scan logic.

Mount the ultrasonic sensor on the servo
A rigid mount matters more than cosmetics for stable readings.
2

Step 2

Create a left-center-right scan loop

Measure distance at three or more angles, store the readings, then compare which direction is safest.


int leftDistance = scanAt(150);
int centerDistance = scanAt(90);
int rightDistance = scanAt(30);

if (centerDistance < 20) {
  if (leftDistance > rightDistance) {
    turnLeft();
  } else {
    turnRight();
  }
} else {
  moveForward();
}

This is the turning point where a toy build starts behaving like a simple autonomous system.

Create a left-center-right scan loop
Discrete scan points are easier to debug than continuous sweeps.
3

Step 3

Tune movement behavior

Reduce motor burst times, then retest in a narrow path. Fast, smaller corrections feel more intelligent than big dramatic turns.

Log your measured distances over serial output so you can understand why the rover chose each direction.

Tune movement behavior
Short turn bursts usually outperform long blind turns.

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