The  goals of this lab are to

  • Understand the ROS coordinate transform message system TF

Deliverables:

  • Plots of the hand trajectories and accuracy measurement
Duration:
  • 1.5 weeks
Deliverables are due on a print-out and delivered at the beginning of the following class.

Instructions:

  • Go through the TF tutorial. Comments:
    • If a process dies, you can manually start “rosrun turtle_tf turtle_tf_listener” in another terminal window.
    • If you have the right combination of Virtualbox/graphic card, rViz might work for you, but is not absolutely necessary. You start it using
      rosrun rviz rviz
    • You will not see anything in Rviz unless you
      1. Change “Fixed Frame” in Global Options to “world”
      2. Add a “TF” node using the “Add” button
      3. Move the turtles around
  • Download baxter_tf, a bag file containing tf messages recorded on the Baxter.
  • Read through the ROS bag file tutorial.
  • Use what you learned in the TF tutorial to
    • Identify all the tf nodes that the Baxter records
    • Find out how the robot’s hands moved with respect to its base
    • Plot the trajectory (in 2D or 3D) that the hands moved. You can either manipulate data that tf_echo spits out or write a tf_listener in C++ or Python
  • Download baxter_tf_pickup and calculate the accuracy with which Baxter can be moved to a desired location for both the left and right arm. Both arms move up and down on a straight line. You can calculate the accuracy by averaging over the end points, and then compare.
 

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