Coding Ireland STEM Report 2024 Have Your Say
Scratch Artificial Intelligence
60 mins
220 points
What you need:
  • Computer/laptop

Autonomous Car

In this lesson we will program a car to drive around a test track with no one driving it except a computer program!

1 - How an autonomous car works

What is an autonomous car?
An autonomous car (also known as a driverless car, self-driving car or  robotic car) is a car that is capable of sensing what is around it and navigating without a person driving.

How does it work?
Autonomous cars use a variety of techniques to detect their surroundings, such as radar, laser light, GPS, odometry and computer vision. They have advanced control systems that interpret sensory information to identify appropriate navigation paths, as well as obstacles and relevant signage.

The following 2 minute video shows some of the different cameras that a Tesla autonomous car uses to sense where the road is and all the different objects that it comes close to such as people and other cars.

2 - Create a new Scratch project

Create a new Scratch project and delete the cat sprite.

3 - Add the car sprite

Included with this step is a car picture that we're going to upload into our Scratch project. First download the picture file onto your computer and then upload it into your project.

You may notice the red, blue and orange ellipses sticking out of the front of the car. We will be using these as the car's sensors to navigate around the track.

4 - Shrink the car

As the car sprite is very large, we'll need to shrink it so that it has room to move around. We're going to shrink it to 10% of it's original size.

Add the following code to the car sprite:

when green flag clicked set size to (10) %

5 - Draw a test track

We're going to use the backdrop editor to draw a racing track. To open the backdrop editor do the following:

  1. Click on the stage backdrop in the bottom right. A blue box should appear around it.
  2. Click on the backdrops tab in the top left. You should now see the backdrop editor.

Next we're going to draw a race track. First we will colour the background green and then we will draw a black track. Follow these steps:

  1. Click the Convert to Bitmap button.
  2. Select the colour green in the Fill tool.
  3. Click on the Paint Bucket tool.
  4. Click on the backdrop to change it's colour to green.
  5. Click on the Convert to Vector button.
  6. Click on the Brush tool.
  7. Select the colour black in the Fill tool.
  8. Set the thickness of the brush to be 90.
  9. Draw a simple loop track by holding down the left button, moving your mouse and then releasing the left button.

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Copyright Notice
This lesson is copyright of Coding Ireland. Unauthorised use, copying or distribution is not allowed.

Scratch is developed by the Lifelong Kindergarten Group at the MIT Media Lab. It is available for free at
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