Skip to main content
LessonGrades 4 - 8

How Does an Ultrasonic Sensor Work?

Two images: A diagram shows a bat using its sonar to locate prey. The bat sends out sound waves and the returning waves provide it with information about the location of a moth. A photograph shows a palm-sized gray and white plastic device with a metal screens inside two orange-rimmed porthole openings (a LEGO ultrasound sensor).Bats use echolocation to find and identify objects in their surroundings. To help robots identify objects, engineers have created ultrasonic sensors that operate using the same principles.

Students learn about how ultrasonic sensors work, reinforcing the connection between this sensor and how humans, bats and dolphins estimate distance. They learn the echolocation process—sound waves transmitted, bounced back and received, with the time difference used to calculate the distance of objects. Two mini-activities, which use LEGO® MINDSTORMS® EV3 robots and ultrasonic sensors, give students a chance to experiment with ultrasonic sensors in preparation for the associated activity. A PowerPoint® presentation explains stimulus-to-response pathways, sensor fundamentals, and details about the LEGO ultrasonic sensor. Pre/post quizzes are provided. This lesson and its associated activity enable students to gain a deeper understanding of how robots can take sensor input and use it to make decisions via programming.

Biological engineers and neuroscientists perceive the human body as a functioning, controlled system, similar to a robot. Research findings are showing that mathematical principles similar to those used in robotics are extremely useful or even necessary for a complete understanding of the human body. Through this lesson, students strengthen their understanding of the functioning of each of the human (and bat) senses by relating them to the different sensors used in robots. Ultrasonic sensors are used in medicine to detect shapes and sizes of otherwise unseen internal body parts. For instance, doctors can determine gender of a fetus in the womb of its mother. Ultrasonic sensors are also used to determine wind speed and direction. Sonar and radar technologies are based on the same concepts.

After this lesson, students should be able to:

  • Describe how ultrasonic sensors work.
  • Compare the ultrasonic sensor to how humans and bats estimate distance.
  • Program the LEGO MINDSTORMS EV3 robot with the ultrasonic sensor.
  • Provide a basic explanation of how sensors are integrated into robots via careful programming.

More Like This