pxt-ev3/docs/getting-started/use.md

Use

Build a robot and drive into the world of robotics!

In this project we will guide you through building a Driving Base Robot and programming it to move straight and turn. You will also build and Object Detector Module, and program it to detect an object. It’s a good idea to have done the Try sequence first.

Connect

What if your school had a multipurpose robot? How would you use it?

Would you use it to clean the school or plant trees?

Build Your Driving Base Robot

Build the robot driving base:

~hint

If clicking the above image doesn't open the instructions, right-click on the image and choose "Save link as..." to download the PDF.

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Make It Move

Code it: Create a program that makes the Driving Base move forward and stop at the finish line, which is 1 meter away.

Start by building this program:

brick.buttonEnter.onEvent(ButtonEvent.Pressed, function () {
    motors.largeBC.steer(0, 50, 1, MoveUnit.Rotations)
})

• Drag a ||motors:steer large motors B+C|| block inside an ||brick:on button|| block.
• Click on the (+) sign.
• Change to 1 rotation.

~hint

Hint: You will have to modify the number of rotations until you find the number that matches the robot moving forward 1 meter and stopping.

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Download: Click Download and follow the instructions to get your code onto your EV3 Brick. Press the center button on the EV3 Brick to run the program.

Make It Turn

Code it: Create a new program that turns the Driving Base 180 degrees.

brick.buttonEnter.onEvent(ButtonEvent.Pressed, function () {
    motors.largeBC.steer(-50, 50, 1, MoveUnit.Rotations)
})

~hint

Hint: You will have to modify the turn ratio and the number of rotations until the robot reaches 180 degrees.

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Download: Click Download and follow the instructions to get your code onto your EV3 Brick. Press the center button on the EV3 Brick to run the program.

Add an Ultrasonic Sensor to Your Driving Base

Build and attach an Ultrasonic Sensor to your driving base:

~hint

If clicking the above image doesn't open the instructions, right-click on the image and choose "Save link as..." to download the PDF.

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Detect an Object

Code it: Create a program that moves the Driving Base and makes it stop 6 cm from the Cuboid.

Create a new program:

brick.buttonEnter.onEvent(ButtonEvent.Pressed, function () {
    motors.largeBC.tank(50, 50)
    sensors.ultrasonic4.setThreshold(UltrasonicSensorEvent.ObjectDetected, 6)
    sensors.ultrasonic4.pauseUntil(UltrasonicSensorEvent.ObjectDetected);
    motors.stopAll()
})

• Drag a ||motors:tank large motors B+C|| motor block inside the ||brick:on button|| block.
• Drag the Ultrasonic Sensor threshold ||sensors:set ultrasonic 4|| block and place it below the motor block.
• Drag a |sensors:pause until ultrasonic 4|| block and place it under the threshold block.
• Drag a ||motors:stop all motors|| block and place it below the sensor block.

~hint

Hint: You will have to modify the values of the Ultrasonic Sensor block until the robot reaches the desired position.

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Download: Click Download and follow the instructions to get your code onto your EV3 Brick. Press the center button on the EV3 Brick to run the program.

Click on the JavaScript tab. Change and test the number value of the Ultrasonic Sensor.

sensors.ultrasonic4.setThreshold(UltrasonicSensorEvent.ObjectDetected, 10)

Congratulations!

You are ready to move on to the next steps. Try a Design Engineering, Coding, or Maker activity.