Zowi’s legs



Robots can move in many different ways: wheels, caterpillar tracks (like tanks), or legs, as is the case with Zowi. But what is the most effective way of getting around? Keep reading to find out.

Robots con diferentes formas de moverse


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Experiment 1 – Two-legged robots

A system of movement based on legs is one of the most complicated. As a human, you are very used to using your legs to walk. But it wasn’t so easy when you were a baby… if you can remember that far back.

Do you remember the walking algorithm in the Choreography project? Now, imagine having to make an algorithm (i.e. a list of instructions) to move each muscle in your legs in order to walk. In reality your brain does this automatically, but a robot has to be programmed. To take a step, each motor in the robot’s legs need to make specific movements. This is pretty complicated, but not impossible.

Piernas humanas Patas de Zowi

But wait, there are advantages too! If the robot’s legs have enough motors, it can climb stairs, sit on a chair, get up from the ground, and many more actions which would not be possible with wheels or caterpillar tracks.

Let’s experiment with Zowi’s movements

  1. Put Zowi upside down.
  2. Now enter the 3, 2, 1 Action! game and create an algorithm to make Zowi take 100 steps forward. You can alternate the speed.
  3. Observe how the four leg motors move.
  4. You can repeat the experiment with some of Zowi’s dance steps. You will then see the difference between dancing and walking. You will also see that some of these movements don’t need the four motors to be moved.

As you’ve seen, the motors are synchronised, allowing Zowi to walk. If they weren’t, Zowi would fall and the leg motors would collide with each other, making them break.

Experiment 2 – What is a servo?

So far we’ve been talking about motors, but… can you imagine if Zowi had the same motor as a car? Its legs would turn and turn at full speed.

To prevent this, a different type of motor has been invented for robots. Zowi uses a type of motor called a servo. The difference between servos and car motors is that they use electricity (rather than fuel).

What’s more, a car motor can go at different speeds, but it cannot make an exact half turn and then stop. A servo can. This is how programmers make robots with legs move.

Servos do have one disadvantage, they can’t make more than a half turn. This means Zowi’s legs cannot make a complete turn (just like your legs).

Servos de Zowi

Let’s check it out

  1. Switch Zowi off and place it upside down, like in the previous experiment.
  2. Move one of its legs. Can it make a complete turn?
  3. Now try the other leg. Can this one make a complete turn?

Servos are very useful actuators which allow robots to move easily. You’ll see how many are used when you build your own robot!

Did you know?

There are different types of servos. Other common servos are continuous rotation servos, which can make complete turns, but in a more controlled manner than car motors.

Moment of inspiration!

If you were to build a robot… what sensors and actuators would it have? How would it move, and what things would it be able to do? Draw your robot, showing which components it would have, and where they would go.