The first robot vacuum cleaner was called Trilobite. The Swedish company Electrolux invented it over 20 years ago.

Trilobite is the name of a very old animal, similar to a crab. It lived many millions of years ago. It ate food from the sea floor.

The robot vacuum cleaner finds dirt on the floor. It also looks a bit like a crab: it is flat and round and has slits on both sides. The slits should look like the crab’s scales. In the robot, the slits are for ventilation.

Today's robot vacuum cleaners still look like trilobites. They are still flat so that they can go under furniture.

The trilobite sends out ultrasonic waves and measures their echo. Ultrasonic waves are very high-pitched sounds that humans cannot hear. When the sound waves hit an obstacle, they bounce back like an echo. Bats, for example, do the same thing to find their way in the dark.

Today, robot vacuum cleaners have infrared sensors, laser sensors or a camera. The sensors work like feelers. They measure the distance to an object or a wall. This way, the robot vacuum cleaners can move around obstacles.

Infrared is a type of light that is invisible. You can only feel it. A laser is a strong light that shines in a straight beam. It is used to measure very accurately.

The Trilobite is a good example of how robots changed. 2 things are important: nature is often the model for how robots work. And they look like animals, so they feel familiar. We humans have had pets for around 2,000 years. That is why home robots often have animal names.