Ultrasonic sensor

The word ultrasonic means a sound that is too high for human hearing. Usually below 20khz 

An ultrasonic sensor use sound to accurately detect objects and measure distances.

Understanding Sound

Sound has important properties and these same properties (physics) apply to ultrasonic sensors too.

“Sonar Principle EN” by Georg Wiora (Dr. Schorsch) – Self drawn with Inkscape.

*Sound travels from a source
*Sound is focussed in a certain direction
*Sound travels over a certain distance
*Sound spreads out in a conical like shape

These physics properties apply to the ultrasonic sensor used in out projects. Most ultrasonic sensors in these project have 2 sensors. These are similar to the ones seen on the mindstorm robots.

The term use in place of sound is BEAM
The angle of this beam is determined by the width of the beam. This is usually an angle of between 8 and 12 degrees
The Beam path is the where the ultrasonic sensor can detect an object. The solid straight lines of the area are sometimes called legs.

Understanding ultrasonic sensors

Beam Path of an ultrasonic sensor

What does this mean?

*The further a beam travels the beam width becomes wider.
*The Beam path detects an object within it path. The target object may not be the first object detected within the path, these objects are known as obstacles.This image show an object as an obstacle in the BEAM path