I’ve reached a point at which the robot can both move and tell me how far away the wall is from it, but I think I’ve done it in a way such that I cannot alter the movement of the robot in response to its distance from the wall. I’m not sure whether the publisher and the subscriber should be in the …

Hello @benradick , After looking at both your script, I could see that the script2 where you are publishing the velocity has no connection with the distance left from the wall (as you haven’t subscribed to the laser topic in the particular script.) I would suggest you to include the subscriber and …

Thanks for your response! When I put the publisher and the subscriber in the same script, I cannot get both to work at the same time. e.g. #! /usr/bin/env python import rospy from sensor_msgs.msg import LaserScan from geometry_msgs.msg import Twist rospy.init_node(“topics_quiz_node”) def callb…

Put your logic and publishing into the callback. Something like so: #! /usr/bin/env python import rospy from sensor_msgs.msg import LaserScan from geometry_msgs.msg import Twist rospy.init_node(“topics_quiz_node”) var = Twist() pub = rospy.Publisher(’/cmd_vel’, Twist, queue_size=1) def callback(…

Ahhhhhhhhhhhhhhhhhhhhhhh. I think I get it. Does the rospy.spin() at the end repeat the whole code starting from the rospy.init_node line?

No, read about rospy.spin() here: [image] What is rospy.spin(), ros::spin(), ros::spinOnce(), and what are they for? Knowledgebase rospy roscpp First…

I'm currently attempting the Topics quiz. I'm so close but I'm stuck!

Course Support ROS Basics In 5 Days (Python)

bayodesegun July 14, 2020, 10:32am 6

No, read about rospy.spin() here: