12. Treasure Hunt

Arrange a maze in your room and place six different color cards in six corners. Then control PiCar-X to search for these color cards one by one!

Note

You can download and print the PDF Color Cards for color detection.

Run the Code

cd ~/picar-x/example
sudo python3 12.treasure_hunt.py

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: http://192.168.18.113:9000/mjpg

Code

from picarx import Picarx
from time import sleep
from robot_hat import Music,TTS
from vilib import Vilib
import readchar
import random
import threading

px = Picarx()

music = Music()
tts = TTS()

manual = '''
Press keys on keyboard to control Picar-X!
    w: Forward
    a: Turn left
    s: Backward
    d: Turn right
    space: Say the target again
    ctrl+c: Quit
'''

color = "red"
color_list=["red","orange","yellow","green","blue","purple"]

def renew_color_detect():
    global color
    color = random.choice(color_list)
    Vilib.color_detect(color)
    tts.say("Look for " + color)

key = None
lock = threading.Lock()
def key_scan_thread():
    global key
    while True:
        key_temp = readchar.readkey()
        print('\r',end='')
        with lock:
            key = key_temp.lower()
            if key == readchar.key.SPACE:
                key = 'space'
            elif key == readchar.key.CTRL_C:
                key = 'quit'
                break
        sleep(0.01)

def car_move(key):
    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(-30)
        px.forward(80)
    elif 'd' == key:
        px.set_dir_servo_angle(30)
        px.forward(80)


def main():
    global key
    Vilib.camera_start(vflip=False,hflip=False)
    Vilib.display(local=False,web=True)
    sleep(0.8)
    print(manual)

    sleep(1)
    _key_t = threading.Thread(target=key_scan_thread)
    _key_t.setDaemon(True)
    _key_t.start()

    tts.say("game start")
    sleep(0.05)
    renew_color_detect()
    while True:

        if Vilib.detect_obj_parameter['color_n']!=0 and Vilib.detect_obj_parameter['color_w']>100:
            tts.say("will done")
            sleep(0.05)
            renew_color_detect()

        with lock:
            if key != None and key in ('wsad'):
                car_move(key)
                sleep(0.5)
                px.stop()
                key =  None
            elif key == 'space':
                tts.say("Look for " + color)
                key =  None
            elif key == 'quit':
                _key_t.join()
                print("\n\rQuit")
                break

        sleep(0.05)

if __name__ == "__main__":
    try:
        main()
    except KeyboardInterrupt:
        pass
    except Exception as e:
        print(f"ERROR: {e}")
    finally:
        Vilib.camera_close()
        px.stop()
        sleep(.2)

How it works?

To understand the basic logic of this code, you can focus on the following key parts:

1. Initialization and Imports: Import statements at the beginning of the code to understand the libraries being used.

2. Global Variables: Definitions of global variables, such as color and key, which are used throughout the code to track the target color and keyboard input.

3. renew_color_detect() : This function selects a random color from a list and sets it as the target color for detection. It also uses text-to-speech to announce the selected color.

4. key_scan_thread() : This function runs in a separate thread and continuously scans for keyboard input, updating the key variable with the pressed key. It uses a lock for thread-safe access.

5. car_move(key) : This function controls the movement of the PiCar-X based on the keyboard input (key). It sets the direction and speed of the robot’s movement.

6. main() :The primary function that orchestrates the overall logic of the code. It does the following:

   • Initializes the camera and starts displaying the camera feed.

   • Creates a separate thread to scan for keyboard input.

   • Announces the start of the game using text-to-speech.

   • Enters a continuous loop to:

     • Check for detected colored objects and trigger actions when a valid object is detected.

     • Handle keyboard input to control the robot and interact with the game.

   • Handles quitting the game and exceptions like KeyboardInterrupt.

   • Ensures that the camera is closed and the PiCar-X is stopped when exiting.

By understanding these key parts of the code, you can grasp the fundamental logic of how the PiCar-X robot responds to keyboard input and detects and interacts with objects of a specific color using the camera and audio output capabilities.