Zowi’s eyes

How come cats can see in the dark but humans can’t? Did you know that dogs can hear sounds can’t to detect? How do CCTV cameras see at night?

Our senses can only capture part of the phenomena going on around us. Dogs can hear more high-pitched sounds that humans can. Cats’ eyes allow more light to pass through, which allows them to see better in the dark. CCTV cameras work with a special type of light that we don’t see; infrared light.

Experiment 1

  1. Restart Zowi and close the app. Press button B on the back to enable MODE 1: Obstacle dodger. You will see how Zowi is very happy when it starts off walking.
  2. pulsarB

  3. Watch carefully and see what happens when it reaches a wall or when there’s a large obstacle ahead. Zowi stops. How does it do this? How does it know there’s an obstacle ahead? Maybe it can see it?
  4. Draw the curtains and switch off the lights so that everything is in darkness. Now repeat the previous steps. What happens? Does Zowi crash into the obstacle?

Although it appears as though Zowi’s head has two eyes, in actual fact, they are two very special sensors. To know if there’s an obstacle ahead, Zowi emits an ultrasound (a sound wave too high pitched for humans to detect).

The two dark circles appear to be Zowi’s eyes, but actually, one of them is the “ultrasound mouth” and the other is the “ultrasound ear”.

When that sound collides with an object ahead, it bounces back as a wave.

After emitting this ultrasonic “scream”, Zowi waits and counts until it hears the echo bounce back.

zowi_US_distance

This way, Zowi can calculate the exact distance away from the object.

Experiment 2

  1. Press button B to enable MODE 1: Obstacle dodger.
  2. Place some objects in front of Zowi and investigate to find out at what distance it can detect them.
  3. Have a go with different types of objects:
  • A mesh bag (like the ones that citrus fruits are sold in)
  • A small object (which is lower than Zowi’s eyes)

What happens with these objects and why?

Did you know…?

Bats use the same mechanism to avoid collisions as they fly. They make a very high-pitched sound and listen out for it bouncing back from any obstacles. This way, they know if they need to change the direction they are flying in. Isn’t that incredible?