python_twist.rst

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Twist

We already know how to make PiCrawler assume a specific pose, the next step is to combine the poses to form a continuous action.

Here, PiCrawler's four feet are up and down in twos, jumping with the music.

Run the Code

cd ~/picrawler/examples
sudo python3 twist.py

Code

Note

You can Modify/Reset/Copy/Run/Stop the code below. But before that, you need to go to source code path like picrawler\examples. After modifying the code, you can run it directly to see the effect.

from picrawler import Picrawler
from robot_hat import Music

music = Music()
crawler = Picrawler()


def twist(speed):
    new_step=[[50, 50, -80], [50, 50, -80],[50, 50, -80], [50, 50, -80]]
    for i in range(4):
        for inc in range(30, 60, 5):
            rise = [50,50,(-80+inc*0.5)]
            drop = [50,50,(-80-inc)]

            new_step[i]=rise
            new_step[(i+2)%4] = drop
            new_step[(i+1)%4] = rise
            new_step[(i-1)%4] = drop
            # print(new_step)
            crawler.do_step(new_step,speed)


def main():

    music.music_play('./musics/sports-Ahjay_Stelino.mp3')
    music.music_set_volume(20)

    while True:
        twist(speed=100)


if __name__ == "__main__":
    main()

How it works?

In this code, you need to pay attention to this part:

def twist(speed):
    ## [right front],[left front],[left rear],[right rear]
    new_step=[[50, 50, -80], [50, 50, -80],[50, 50, -80], [50, 50, -80]]
    for i in range(4):
        for inc in range(30,60,5):
            rise = [50,50,(-80+inc*0.5)]
            drop = [50,50,(-80-inc)]

            new_step[i]=rise
            new_step[(i+2)%4] = drop
            new_step[(i+1)%4] = rise
            new_step[(i-1)%4] = drop
            crawler.do_step(new_step,speed)

Simply put, it uses two layers of for loops to make the new_step array produce continuous and regular changes, and at the same time, crawler.do_step() executes the posture to form a continuous action.

You can intuitively get the coordinate value array corresponding to each pose from :ref:`py_posture`.

In addition, the example also played background music. The implementation method is as follows.

Play music by importing the following libraries.

from robot_hat import Music

Declare a Music object.

music = Music()

Play the background music in the picrawler/examples/musics directory and set the volume to 20. You can also add music to the musics folder via :ref:`filezilla`.

music.music_play('./musics/sports-Ahjay_Stelino.mp3')
music.music_set_volume(20)

Note

You can add different sound effects or music to musics or sounds folder via :ref:`filezilla`.