“This instructable explains how to pinpoint the location of an object using an Arduino, two ultrasonic sensors, and Herons formula for triangles. There are no moving parts.
Herons formula allows you to calculate the area of any triangle for which all sides are known. Once you know the area of a triangle, you are then able to calculate the position of a single object (relative to a known baseline) using trigonometry and Pythagoras.
The accuracy is excellent. Large detection areas are possible using commonly available HC-SR04, or HY-SRF05, ultrasonic sensors.
Construction is simple … all you require is a sharp knife, two drills, a soldering iron, and a wood saw.
Images
The video clip shows the unit in operation. Photo 1 shows the assembled echo locator Photo 2 shows a typical display. The object is the red (flashing) dot. Photo 3 shows the video test setup. It was necessary to position the two HY-SRF05 ultrasonic sensors 50cm below the baseline to completely illuminate the detection area with sound.”