Introduction and Resources

The goal of this lab is to gain experience using the tf system in ROS. Unfortunately, the Python API for tf is not very well documented on the ROS wiki. Here are some places you can get information:

• Official tf tutorials
• Using Python tf (A ROS wiki page. This is not very complete.)

Here is some example code illustrating the process of transforming a stamped point from one coordinate frame to another using tf: tf_demo.py

Proportional Navigation: Practicing with tf

• Download and unzip turtlebot_simple_nav.zip to your cs354_ws directory. Build and source the package.
• The scripts folder contains three files:
  • turtlebot_simple_nav.py - An unfinished node designed to navigate the Turtlebot to an arbitrary point. The code here should be similar to the code you wrote for PA1. You'll need to modify this node so that it uses tf to perform the necessary coordinate transforms.
  • goal_publisher.py - This node randomly selects a goal location and publishes it as a PointStamped message in the /odom coordinate frame.
  • mouse_simple_nav_teleop.py - This is a modified version of the teleop node from PA1. It can be used to publish goal locations provided with the mouse.
• Complete turtlebot_simple_nav.py so that it correctly navigates to the published goal location. Once you have your code working in Gazebo, try it out on one of the real Turtlebots.
• Submit your completed turtlebot_simple_nav.py through Canvas. Make sure that the names of all group members appear in the file.