ACTUATORS AND MECHANICS

Maqueen Movement Challenge:

Ready to put your DC motor control skills to the test? These challenges will help you gain precise control over your Maqueen robot's movements. Remember, in robotics, accuracy is key!

Challenge 1: Precise Distance Control

Your mission, should you choose to accept it, is to make your Maqueen robot travel exact distances.

Setup:

Mark the following distances on the floor:

• 500mm (50cm)

• 1000mm (1m)

• 2000mm (2m)

Place your Maqueen at the starting point.

Task:

Program your Maqueen to travel each of these distances accurately. Here's how to approach this:

1. Start with a constant speed of 128 (half of the maximum 255).

2. Experiment with different durations to find out how long the Maqueen needs to run to cover each distance.

3. Record your findings and see if you can identify a pattern.

Example Code Structure:

from microbit import *

from maqueenplusv2 import *

init_maqueen()

def drive_for_duration(duration_ms, speed=128):

    motors(speed, FORWARD, speed, FORWARD)

    sleep(duration_ms)

    stop()

while True:

    if button_a.is_pressed():

        sleep(500) # Allows you to move out of the way

        drive_for_duration(2000) # # Drive for 2 seconds

Extension

Can you create a drive_distance function that takes a distance in millimeters as an argument?

def drive_distance(distance_mm, speed=128):

    # Your code here

    pass

# Example usage:

drive_distance(500)  # Drive 500mm

Things to Consider:

• What's the relationship between duration and distance?

• Does the speed affect this relationship? Try different speeds and see!

Challenge 2: Accurate Turning

Now that you can move in straight lines, let's add some turns!

Task:

Program your Maqueen to turn exact angles. Start with 90 degrees, then try 45 degrees and 180 degrees.

Approach:

Use the motors() function to turn the robot. Remember, to turn left, the right motor should move forward and the left motor backward (or vice versa for turning right).

Start with a constant speed (like 128) and experiment with different durations.

Use the stop() function after each turn for more precise control.

Example Code Structure:

def turn_for_duration(duration_ms, direction='left', speed=128):

    if direction == 'left':

        motors(speed, BACKWARD, speed, FORWARD)

    else:  # right turn

        motors(speed, FORWARD, speed, BACKWARD)

    sleep(duration_ms)

    stop()

# Example usage:

turn_for_duration(500, 'left')  # Turn left for 0.5 seconds

Extension:

Can you create a turn_angle function that takes an angle in degrees as an argument?

def turn_angle(angle_degrees, direction='left', speed=128):

    # Your code here

    pass

# Example usage:

turn_angle(90, 'right')  # Turn 90 degrees to the right

Things to Consider:

• How does the turning radius of your Maqueen affect its rotation?

• Is there a relationship between the angle of turn and the duration of motor activation?

• Does the speed affect the accuracy of your turns?

Challenge 3: The Square Dance

Remember how we programmed the Maqueen to move in a square earlier? Now let's see if we can do it with some accuracy.
Combine your new drive_distance and turn_angle functions to make your Maqueen drive in a perfect square!

Example Code Structure:

def drive_square(side_length_mm):

    for _ in range(4):

        drive_distance(side_length_mm)

        turn_angle(90, 'left')

# Example usage:

drive_square(500)  # Drive a 500mm square