Understanding How Ultrasonic Sensors Work

What is an ultrasonic sensor?

An ultrasonic sensor is an instrument that measures the distance to an object using ultrasonic sound waves.
An ultrasonic sensor uses a transducer to send and receive ultrasonic pulses that relay back information about an object’s proximity. 
High-frequency sound waves reflect from boundaries to produce distinct echo patterns.

How Ultrasonic Sensors Work.

Ultrasonic sensors work by sending out a sound wave at a frequency above the range of human hearing.  The transducer of the sensor acts as a microphone to receive and send the ultrasonic sound. Our ultrasonic sensors, like many others, use a single transducer to send a pulse and to receive the echo.  The sensor determines the distance to a target by measuring time lapses between the sending and receiving of the ultrasonic pulse.

The working principle of this module is simple.  It sends an ultrasonic pulse out at 40kHz which travels through the air and if there is an obstacle or object, it will bounce back to the sensor.  By calculating the travel time and the speed of sound, the distance can be calculated.  

Why use an Ultrasonic Sensor?

Ultrasound is reliable in any lighting environment and can be used inside or outside.  Ultrasonic sensors can handle collision avoidance for a robot, and being moved often, as long as it isn’t too fast.  

Ultrasonics are so widely used, they can be reliably implemented in grain bin sensing applications, water level sensing, drone applications and sensing cars at your local drive-thru restaurant or bank.

Ultrasonic rangefinders are commonly used as devices to detect a collision.  

Ultrasonic Sensors are best used in the non-contact detection of:

• Presence

• Level

• Position

• Distance

Non-contact sensors are also referred to as proximity sensors.

Ultrasonics are Independent of:

• Light

• Smoke

• Dust

• Color

• Material (except for soft surfaces, i.e. wool, because the surface absorbs the ultrasonic sound wave and doesn’t reflect sound.)

 Long range detection of targets with varied surface properties.

 Ultrasonic sensors are superior to infrade sendors, because they aren’t affected by smoke or black materials, however, soft materials which don’t reflect the sonar (ultrasonic) waves very well may cause issues. It’s not a perfect system, but it’s good and reliable.