11. Video Car

This program will provide a First Person View from the PiCar-X! Use the keyboards WSAD keys to control the direction of movement, and the O and P to adjust the speed.

Run the Code

cd ~/picar-x/example
sudo python3 11.video_car.py

Once the code is running, you can see what PiCar-X is shooting and control it by pressing the following keys.

• O: speed up

• P: speed down

• W: forward

• S: backward

• A: turn left

• D: turn right

• F: stop

• T: take photo

• Ctrl+C: quit

View the Image

After the code runs, the terminal will display the following prompt:

No desktop !
* Serving Flask app "vilib.vilib" (lazy loading)
* Environment: production
WARNING: Do not use the development server in a production environment.
Use a production WSGI server instead.
* Debug mode: off
* Running on http://0.0.0.0:9000/ (Press CTRL+C to quit)

Then you can enter http://<your IP>:9000/mjpg in the browser to view the video screen. such as: https://192.168.18.113:9000/mjpg

code

#!/usr/bin/env python3

from robot_hat.utils import reset_mcu
from picarx import Picarx
from vilib import Vilib
from time import sleep, time, strftime, localtime
import readchar

import os
user = os.getlogin()
user_home = os.path.expanduser(f'~{user}')

reset_mcu()
sleep(0.2)

manual = '''
Press key to call the function(non-case sensitive):

    O: speed up
    P: speed down
    W: forward
    S: backward
    A: turn left
    D: turn right
    F: stop
    T: take photo

    Ctrl+C: quit
'''


px = Picarx()

def take_photo():
    _time = strftime('%Y-%m-%d-%H-%M-%S',localtime(time()))
    name = 'photo_%s'%_time
    path = f"{user_home}/Pictures/picar-x/"
    Vilib.take_photo(name, path)
    print('\nphoto save as %s%s.jpg'%(path,name))


def move(operate:str, speed):

    if operate == 'stop':
        px.stop()
    else:
        if operate == 'forward':
            px.set_dir_servo_angle(0)
            px.forward(speed)
        elif operate == 'backward':
            px.set_dir_servo_angle(0)
            px.backward(speed)
        elif operate == 'turn left':
            px.set_dir_servo_angle(-30)
            px.forward(speed)
        elif operate == 'turn right':
            px.set_dir_servo_angle(30)
            px.forward(speed)



def main():
    speed = 0
    status = 'stop'

    Vilib.camera_start(vflip=False,hflip=False)
    Vilib.display(local=True,web=True)
    sleep(2)  # wait for startup
    print(manual)

    while True:
        print("\rstatus: %s , speed: %s    "%(status, speed), end='', flush=True)
        # readkey
        key = readchar.readkey().lower()
        # operation
        if key in ('wsadfop'):
            # throttle
            if key == 'o':
                if speed <=90:
                    speed += 10
            elif key == 'p':
                if speed >=10:
                    speed -= 10
                if speed == 0:
                    status = 'stop'
            # direction
            elif key in ('wsad'):
                if speed == 0:
                    speed = 10
                if key == 'w':
                    # Speed limit when reversing,avoid instantaneous current too large
                    if status != 'forward' and speed > 60:
                        speed = 60
                    status = 'forward'
                elif key == 'a':
                    status = 'turn left'
                elif key == 's':
                    if status != 'backward' and speed > 60: # Speed limit when reversing
                        speed = 60
                    status = 'backward'
                elif key == 'd':
                    status = 'turn right'
            # stop
            elif key == 'f':
                status = 'stop'
            # move
            move(status, speed)
        # take photo
        elif key == 't':
            take_photo()
        # quit
        elif key == readchar.key.CTRL_C:
            print('\nquit ...')
            px.stop()
            Vilib.camera_close()
            break

        sleep(0.1)


if __name__ == "__main__":
    try:
        main()
    except Exception as e:
        print("error:%s"%e)
    finally:
        px.stop()
        Vilib.camera_close()