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Lesson 8 Advanced Obstacle Avoidance

Have you ever wondered how robots can navigate through rooms without bumping into furniture? Today, we’re going to teach our Mars Rover to do just that! We’ll combine two different types of sensors to create a super-smart obstacle avoidance system.

How Sensors Help Robots “See”

Let’s think about how we use our senses:

  • Infrared Sensors work like bats using echolocation! They send out invisible infrared light and listen for it to bounce back from objects. If the light returns quickly, there’s an obstacle nearby.

  • Ultrasonic Sensors work with sound waves we can’t hear. They send out high-frequency sound and measure how long it takes to echo back. Longer time means the object is farther away.

When we use both sensors together, our Rover gets a much better understanding of its surroundings - just like using both your eyes and ears to navigate a dark room!

Learning Objectives

  • Combine ultrasonic and infrared sensors to create an advanced obstacle avoidance system

  • Program your Mars Rover to automatically sense and navigate around obstacles

Building Our Super-Smart Rover

Remember the obstacle avoidance program we created earlier? We’re going to use that as our starting point and make it even better!

  1. First, Connecting the APP to GalaxyRVR.

  2. Now, let’s open our previous infrared sensor project from Lesson 6 IR Obstacle as a template. Click on “File” and find your saved IR obstacle avoidance project.

    ../_images/7_avoid_open.png

  3. Before we make changes, let’s save a copy so we don’t lose our original work. Click “Save as a copy.”

    ../_images/7_avoid_save_copy.png

  4. Give your new project a cool name like “Super Smart Rover” or “Advanced Obstacle Avoidance.”

    ../_images/7_avoid_save_rename.png

  5. Now let’s add our ultrasonic sensor! Drag out the when distance < 15 cm block. This will be our “early warning system” that detects obstacles from farther away.

    ../_images/7_avoid_when.png

  6. To prevent confusion, we’ll add a stop other scripts in sprite block. This ensures our Rover only follows one set of instructions at a time.

    ../_images/7_avoid_stop.png

  7. When the ultrasonic sensor detects something close, we want our Rover to back up to a safe distance.

    ../_images/7_avoid_backward.png

  8. Now we need to turn away from the obstacle. The Rover will turn for one second - you can choose left or right turn!

    ../_images/7_avoid_turn.png

  9. Finally, we tell the Rover to continue moving forward on its new path.

    ../_images/7_avoid_go.png

Amazing! Now you have a Rover that uses three sensors working together like a team:

  • The front ultrasonic sensor spots distant obstacles

  • The left IR sensor detects objects on the left side

  • The right IR sensor watches the right side

Test your program and watch how smoothly your Rover navigates around obstacles. Try creating an obstacle course and see if your Rover can complete it without any crashes!

Challenge: Can you modify the turning time or distance to make your Rover even better at avoiding obstacles?