图 31 大象

#!/usr/bin/env pybricks-micropython

"""
Example LEGO® MINDSTORMS® EV3 Elephant Program
----------------------------------------------

This program requires LEGO® EV3 MicroPython v2.0.
Download: https://education.lego.com/en-us/support/mindstorms-ev3/python-for-ev3

Building instructions can be found at:
https://education.lego.com/en-us/support/mindstorms-ev3/building-instructions#building-expansion
"""

from pybricks.hubs import EV3Brick
from pybricks.ev3devices import Motor, ColorSensor, TouchSensor
from pybricks.parameters import Port, Direction, Color, Button
from pybricks.tools import wait, StopWatch
from pybricks.media.ev3dev import SoundFile

# Initialize the EV3 brick.
ev3 = EV3Brick()

# Configure the legs motor, which moves all four legs.  Set the motor
# direction to counterclockwise, so that positive speed values make
# the legs move forward.
legs_motor = Motor(Port.A, Direction.COUNTERCLOCKWISE)

# Configure the trunk motor.  Set the motor direction to
# counterclockwise, so that positive speed values make the trunk move
# upward.
trunk_motor = Motor(Port.B, Direction.COUNTERCLOCKWISE)

# Configure the neck motor with default settings.
neck_motor = Motor(Port.D)

# Set up the Touch Sensor.  It is used to detect when the trunk has
# moved to its maximum position.
touch_sensor = TouchSensor(Port.S1)

# Set up the Color Sensor.  It is used to detect the red beam when the
# neck has moved to its maximum position.
color_sensor = ColorSensor(Port.S4)

# Set up the Timer.  It is used to exit the input loop after 1 second.
timer = StopWatch()


def reset():
    # This function resets the model to its resting position.

    # Run the neck motor until the red beam is detected.
    neck_motor.run(750)
    while color_sensor.color() != Color.RED:
        wait(10)
    neck_motor.brake()

    # Run the trunk motor until the Touch Sensor is pressed.
    trunk_motor.run(600)
    while not touch_sensor.pressed():
        wait(10)
    trunk_motor.brake()

    # Play a sound.
    ev3.speaker.play_file(SoundFile.ELEPHANT_CALL)

    # Run the neck and trunk motors to their resting positions.
    neck_motor.run_angle(-600, 700, wait=False)
    trunk_motor.run_angle(-900, 750)
    wait(0.2)

    # Reset the neck and trunk motors' angles to "0."  This means that
    # when they rotate to "0" later on, they return to their resting
    # positions.
    neck_motor.reset_angle(0)
    trunk_motor.reset_angle(0)


def grab():
    # This function grabs and picks up an object.

    # Reset the model to its resting position.
    reset()

    # Run a sequence of movements using the neck and trunk motors to
    # grab and pick up an object.
    trunk_motor.run_angle(1000, 300, wait=False)
    neck_motor.run_angle(1500, 350)
    neck_motor.run_angle(-750, 350)
    neck_motor.run_time(-150, 1000, wait=False)
    trunk_motor.run_angle(-700, 500)
    trunk_motor.run_angle(-300, 300, wait=False)
    neck_motor.run_angle(450, 400)


# Reset the model to its resting position.
reset()

# This is the main part of the program.  It is a loop that repeats
# endlessly.
#
# First, it resets the Timer and the steps variable.
# Second, it waits for commands given by pressing the Brick Buttons.
# Finally, it runs the legs motor if the steps variable is not "0."
#
# Then the process starts over, so it can accept new commands.
while True:

    # Reset the Timer and the steps variable.
    timer.reset()
    steps = 0

    # Wait until any Brick Button is pressed.
    while not any(ev3.buttons.pressed()):
        wait(10)

    # Respond to the Brick Button press.
    while timer.time() < 1000:
        # Check whether Up Button is pressed, and increase the steps
        # variable by 1 if it is.
        if Button.UP in ev3.buttons.pressed():
            steps += 1

            # Reset the Timer to enable entering multiple commands.
            timer.reset()
            ev3.speaker.beep(600)

            # To avoid registering the same command again, wait until
            # the Up Button is released before continuing.
            while Button.UP in ev3.buttons.pressed():
                wait(10)

        # Check whether Down Button is pressed, and decrease the steps
        # variable by 1 if it is.
        if Button.DOWN in ev3.buttons.pressed():
            steps -= 1

            # Reset the Timer to enable entering multiple commands.
            timer.reset()
            ev3.speaker.beep(1200)

            # To avoid registering the same command again, wait until
            # the Down Button is released before continuing.
            while Button.DOWN in ev3.buttons.pressed():
                wait(10)

        # Lift the trunk and roar.
        if Button.LEFT in ev3.buttons.pressed():
            trunk_motor.run(300)
            while not touch_sensor.pressed():
                wait(10)
            trunk_motor.run_angle(-100, 30)
            reset()

        # Grab an object.
        if Button.RIGHT in ev3.buttons.pressed():
            grab()

        # Play a sound.
        if Button.CENTER in ev3.buttons.pressed():
            ev3.speaker.play_file(SoundFile.ELEPHANT_CALL)

    # Check if the steps variable is not "0."
    if steps != 0:
        # Run the legs motor for the number of steps.  Each step
        # requires the motor to turn 900 degrees.
        angle = 900 * steps
        legs_motor.run_angle(1000, angle)