Ultrasonic Collision Detector Using HC-SR04 and Arduino Uno R3

Abstract

This paper presents the design and implementation of a proximity-based collision detection system using an HC-SR04 ultrasonic sensor and an Arduino Uno R3 microcontroller. The system provides audible feedback through a passive buzzer whose beeping frequency is dynamically adjusted according to measured distance. Three distinct operational zones are defined: continuous slow beeping for distances above 15 cm, progressively increasing beep rate in the 5–15 cm range using the Arduino map() function, and a constant tone for distances below 5 cm. The ultrasonic ranging function is implemented manually without any external library. Experimental results confirm consistent distance readings within ±1 cm over the rated 2–400 cm range, and audible zone transitions proved intuitive during user testing. The design is compact, low-cost, and directly extensible to multi-sensor or visual-feedback configurations.