I created code which making turtlebot 2 following me depend on detecting my face and chose a value of velocity 0.2 m/s
my issue is the movement of the robot when disappearing my face suddenly which making turtlebot stops suddenly, I need to make decreasing its velocity gradually like this figure [link text](https://www.google.com.eg/search?q=linear+velocity+with+time&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi754nI8_HgAhXCxbwKHRJ3D_gQ_AUIDigB&biw=1855&bih=952#imgrc=fbTRSzhfqRk8uM:)
my experience not good in ROS
I need to change the line `self.twist.linear.x = 0.05` by the linear relationship between velocity and time as shown in the figure in the link, I mean that turtlebot will stop after a certain time, for example, 20 second
my full code:
#!/usr/bin/env python
import rospy
from sensor_msgs.msg import Image
from geometry_msgs.msg import Twist
import cv2, cv_bridge
face_cascade = cv2.CascadeClassifier('/home/redhwan/1/run-webcam/Face-Detect-Demo-by-Ali-master/haarcascade_frontalface_default.xml' )
class Face_detection:
def __init__(self):
self.bridge = cv_bridge.CvBridge()
self.image_sub = rospy.Subscriber('/usb_cam/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')
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
faces = face_cascade.detectMultiScale( gray,scaleFactor=1.1,minNeighbors=5,minSize=(30, 30),flags=cv2.cv2.CASCADE_SCALE_IMAGE)
faces = face_cascade.detectMultiScale(gray, 1.3, 5)
if(type(faces) != tuple):
for (x, y, w, h) in faces:
cv2.rectangle(image, (x, y), (x+w, y+h), (0, 255, 0), 2)
self.twist.linear.x = 0.2
self.cmd_vel_pub.publish(self.twist)
cv2.imshow('face ', image)
cv2.waitKey(3)
if(type(faces) == tuple):
self.twist.linear.x = 0.05
self.cmd_vel_pub.publish(self.twist)
rospy.init_node('face_detection')
follower = Face_detection()
rospy.spin()
please help me or any suggestion
Thank you in advance
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