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#!/usr/bin/env python3
# BEGIN ALL
import rospy, cv2, cv_bridge, numpy
from sensor_msgs.msg import Image
from geometry_msgs.msg import Twist
class Follower:
def __init__(self):
self.bridge = cv_bridge.CvBridge()
cv2.namedWindow("window", 1)
self.image_sub = rospy.Subscriber('camera/rgb/image_raw',
Image, self.image_callback)
self.cmd_vel_pub = rospy.Publisher('cmd_vel_mux/input/teleop',
Twist, queue_size=1)
self.twist = Twist()
def image_callback(self, msg):
image = self.bridge.imgmsg_to_cv2(msg,desired_encoding='bgr8')
hsv = cv2.cvtColor(image, cv2.COLOR_BGR2HSV)
lower_yellow = numpy.array([ 10, 10, 10])
upper_yellow = numpy.array([255, 255, 250])
mask = cv2.inRange(hsv, lower_yellow, upper_yellow)
h, w, d = image.shape
search_top = 3*h/4
search_bot = 3*h/4 + 20
mask[0:search_top, 0:w] = 0
mask[search_bot:h, 0:w] = 0
M = cv2.moments(mask)
if M['m00'] > 0:
cx = int(M['m10']/M['m00'])
cy = int(M['m01']/M['m00'])
cv2.circle(image, (cx, cy), 20, (0,0,255), -1)
# BEGIN CONTROL
err = cx - w/2
self.twist.linear.x = 0.2
self.twist.angular.z = -float(err) / 100
self.cmd_vel_pub.publish(self.twist)
# END CONTROL
cv2.imshow("window", image)
cv2.waitKey(3)
rospy.init_node('follower')
follower = Follower()
rospy.spin()
# END ALL