Otto’s eyes

Why can’t people see at night and cats can? Do you know that dogs can hear sounds that you can’t? How do surveillance cameras see at night? And how do bats see if they are blind !?
Read on to find out who else has very special eyes …

Our senses are prepared to capture only a part of all the phenomena that occur around us.

Dogs’ ears can hear higher pitched sounds than humans.
Cats’ eyes let in more light and therefore can see something better in the dark.
Night surveillance cameras work with a type of light that we do not see, infrared light.
But the ones that interest us the most now are bats and their ability to see completely in the dark. How do they do it?

These mammals emit a very high pitched sound from their mouths, called ultrasounds. Then, if there are objects in front, the sound bounces off those objects and returns to the bat, allowing this animal to know if those objects are near or far.

Zowi has this same ability. If you want to know how it works, continue with experiment 1.

Did you know…?
Bats make two types of sounds. The little sounds you hear bats make are not ultrasounds. Humans cannot hear ultrasounds. However, if they are recorded and the sound changed, we can hear them. Click here to listen to the ultrasound that bats make.

Bats are not the only animals that make a sound to detect obstacles. Dolphins also have this ability. There are even studies that say that humans can do it!

By the way, this is called Echolocation.

Experiment 1 – “Bat-Zowi …”
Although what Zowi has on his head looks like eyes, it is actually an “ultrasound sensor.” The sensors, as we saw in the project “The shape of a Robot”, are components that allow the robot to capture information from the outside world.
To know if there are any obstacles ahead, Zowi emits an ultrasound, just like bats.
When that sound hits an object in front, the sound bounces back as it is a wave.


After emitting that ultrasonic “scream”, Zowi waits and counts the time that passes until he hears the echo bounced.

In this way, both Zowi and the bats can calculate the exact distance that separates him from objects.


Let’s experiment with the Zowi distance sensor

Shut down Zowi and close the App.
Power up Zowi and press the A button to enter obstacle avoidance mode.
How far away does Zowi detect objects in obstacle avoidance mode?
Turn off the lights. Does it still detect objects if there is no light?
Do you have a mesh bag at home? Like bags of oranges. If so, try putting him in front of Zowi. Detect it?
As you can see, Zowi’s eyes have their advantages and disadvantages, but it is clear that it is a very useful sensor for robots.

Did you know…?
Zowi’s two dark circles look like eyes, but in reality one is the “ultrasound mouth”, where it emits ultrasound, and the other is the “ultrasound ear”, where it receives the reflected waves.

Experiment 2 – “… And his enemies”

The ultrasound sensor that Zowi has is very useful for detecting things. However, it does have some downsides.

Zowi is not able to detect objects when he is looking at them from the side, since the bouncing waves do not return to Zowi.
sloping wall

Also, the flatter the object, the better. This way they can bounce more straight back to Zowi.
Zowi can’t see a ball well

And if we put something smaller than his eye level in front of Zowi, does he detect it?
Now try these same cases with the Zowi distance sensor. Which one gives less problems?

Inspiration moment!
Do you know what else the ultrasonic sensor can be used for? Search the internet and you will see why we said before that it is so useful.