Welcome to ROSMASTER M3 repository

QR Code Motion Control

1. Introduction

This course mainly uses the robot's camera to obtain camera images, recognize QR code information, and control robot movement based on the QR code information.

2. Program Startup

2.1. Startup Commands

For Raspberry Pi 5 users, if the ROS container is not started, you need to start the container first,

xxxxxxxxxx
bringup_m3

Open a terminal inside the container,

xxxxxxxxxx
exec_m3

xxxxxxxxxx
ros2 launch m3_bringup depthcam_demo.launch.py demo:=qrCtrl

Successfully display camera image

Enable QR code recognition and execute commands. Currently, the QR codes that can be recognized in the example are QRCode, with "forward" for moving forward, "back" for moving backward, "left" for turning left, "right" for turning right, and "stop" for stopping.

Press q to close the camera.

3. Core Code

Program code path:

xxxxxxxxxx
~/yahboomM3_ws/code_ws/src/m3_common_demo/m3_common_demo/depthcamera/qrCtrl.py

Import QR code parsing library pyzbar

xxxxxxxxxx
import pyzbar.pyzbar as pyzbar
from PIL import Image

Parse grayscale image to extract QR code information and image position from the image. If there is no QR code in the image, the information is None.

xxxxxxxxxx
def detect_qrcode(image):
    # Convert to grayscale image
    gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
    barcodes = pyzbar.decode(gray)
    for barcode in barcodes:
        # Extract QR code data and bounding box position
        (x, y, w, h) = barcode.rect
        barcodeData = barcode.data.decode("utf-8")
        barcodeType = barcode.type
        # print("[INFO] Found {} barcode: {}".format(barcodeType, barcodeData))
        car_control(barcodeData)
        return barcodeData, (x, y, w, h)
    return None, (0, 0, 0, 0)

Control robot movement based on info string commands.

xxxxxxxxxx
def robot_action(self,data):
    if data == "forward":
        self.pub_vel(0.1,0.0,0.0)
        sleep(0.5)
​
    elif data == "back":
        self.pub_vel(-0.1,0.0,0.0)
        sleep(0.5)
​
    elif data == "left":
        self.pub_vel(0.1,0.0,1.0)
        sleep(0.5)
​
    elif data == "right":
        self.pub_vel(0.1,0.0,-1.0)
        sleep(0.5)
​
    elif data == "stop":
        self.pub_vel(0.0,0.0,0.0)
        sleep(0.5)

Image processing program

xxxxxxxxxx
def image_callback(self, msg):
    frame = self.bridge.imgmsg_to_cv2(msg, desired_encoding='bgr8')
​
    payload, (x, y, w, h) = self.detect_qrcode(frame)
    if payload != None:
        cv2.rectangle(frame, (x, y), (x + w, y + h), (0, 225, 255), 2)
        cv2.putText(frame, payload, (x, y - 10), cv2.FONT_HERSHEY_SIMPLEX, 0.8, (0, 225, 255), 2)
        self.robot_action(payload)
    else:
        self.pub_vel(0.0,0.0,0.0)
​
    cv2.imshow('frame', frame)
​
    if cv2.waitKey(1) & 0xFF == ord('q'):
        self.get_logger().info("Exiting program")
        cv2.destroyAllWindows()
        rclpy.shutdown()
        exit(0)

Appendix (QR Code Images):