2. Keyboard Control

In this project, we will learn how to use the keyboard to remotely control the PiCar-X. You can control the PiCar-X to move forward, backward, left, and right.

Run the Code

cd ~/picar-x/example
sudo python3 2.keyboard_control.py

Press keys on keyboard to control PiCar-X!

• w: Forward

• a: Turn left

• s: Backward

• d: Turn right

• i: Head up

• k: Head down

• j: Turn head left

• l: Turn head right

• ctrl + c: Press twice to exit the program

Code

from picarx import Picarx
from time import sleep
import readchar

manual = '''
Press keys on keyboard to control PiCar-X!
    w: Forward
    a: Turn left
    s: Backward
    d: Turn right
    i: Head up
    k: Head down
    j: Turn head left
    l: Turn head right
    ctrl+c: Quit
'''

def show_info():
    print("\033[H\033[J",end='')  # clear terminal windows
    print(manual)


if __name__ == "__main__":
    try:
        pan_angle = 0
        tilt_angle = 0
        px = Picarx()
        show_info()
        while True:
            key = readchar.readkey()
            key = key.lower()
            if key in('wsadikjl'):
                if 'w' == key:
                    px.set_dir_servo_angle(0)
                    px.forward(80)
                elif 's' == key:
                    px.set_dir_servo_angle(0)
                    px.backward(80)
                elif 'a' == key:
                    px.set_dir_servo_angle(-35)
                    px.forward(80)
                elif 'd' == key:
                    px.set_dir_servo_angle(35)
                    px.forward(80)
                elif 'i' == key:
                    tilt_angle+=5
                    if tilt_angle>35:
                        tilt_angle=35
                elif 'k' == key:
                    tilt_angle-=5
                    if tilt_angle<-35:
                        tilt_angle=-35
                elif 'l' == key:
                    pan_angle+=5
                    if pan_angle>35:
                        pan_angle=35
                elif 'j' == key:
                    pan_angle-=5
                    if pan_angle<-35:
                        pan_angle=-35

                px.set_cam_tilt_angle(tilt_angle)
                px.set_cam_pan_angle(pan_angle)
                show_info()
                sleep(0.5)
                px.forward(0)

            elif key == readchar.key.CTRL_C:
                print("\n Quit")
                break

    finally:
        px.set_cam_tilt_angle(0)
        px.set_cam_pan_angle(0)
        px.set_dir_servo_angle(0)
        px.stop()
        sleep(.2)

How it works?

PiCar-X should take appropriate action based on the keyboard characters read. The lower() function converts upper case characters into lower case characters, so that the letter remains valid regardless of case.

while True:
    key = readchar.readkey()
    key = key.lower()
    if key in('wsadikjl'):
        if 'w' == key:
            pass
        elif 's' == key:
            pass
        elif 'a' == key:
            pass
        elif 'd' == key:
            pass
        elif 'i' == key:
            pass
        elif 'k' == key:
            pass
        elif 'l' == key:
            pass
        elif 'j' == key:
            pass

    elif key == readchar.key.CTRL_C:
        print("\n Quit")
        break