Arduino Dual-Sensor System Combines Ultrasonic and Infrared for Full Obstacle Detection

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A developer tutorial on DEV Community demonstrates how combining an HC-SR04 ultrasonic sensor with an infrared sensor on an Arduino board can overcome the blind spots of each individual sensor. Ultrasonic sensors excel at detecting distant objects across a range of roughly 2cm to 400cm but struggle with soft or angled surfaces that scatter sound waves, while infrared sensors respond quickly at close range but fail on dark surfaces that absorb infrared light. By running both sensors simultaneously, the system uses dual-verification logic so that when one sensor fails, the other serves as a backup — for example, detecting light-colored foam that scatters sound but reflects infrared light. The full hardware setup costs under approximately NT$300 and includes an Arduino Uno or Nano, the HC-SR04 module, and an infrared obstacle detection module. The project is aimed at hobbyists building obstacle-avoidance robots and is described as accessible to high-school-level programmers.

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