Building a Behavior Tree Using the Robot Screen

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Overview

This tutorial demonstrates how to create a task using any of the nodes available in the software using only the robot screen and train by demonstration. This task will be trained to have the robot move through a pick action, followed by waiting in a position in space for a set period of time, and placing the part into a pattern.

Definitions

  • Train By Demonstration - A technique for training a task in which the robot screen is used to teach actions and behaviors.

Creating a Simple Pick Sequence

  1. Move the arm using Zero-G mode to the location that the arm will approach the pick location from.
  2. Press the Action Button on the cuff (round button next to Grasp Button). The menu below will appear, giving the ability to add any of the nodes to the Behavior Tree.
    TBD1.jpg
  3. The first node option highlighted is the Move-to Node. Press the Action Button again to train a move-to node using the current pose of the arm.
  4. The Move-To node will be created as a child of the "task" [Sequence Node].
    TBD2.jpg
  5. Move the arm in zero-g mode to the pick location.
  6. Create another Move-To Node in the location of the pick.
    TBD21.jpg
  7. Press the Action Button on the cuff. Scroll to and select the Wait Node.
    TBD3.jpg
  8. The wait node defaults to 5s. This can be edited to a shorter length of time by clicking the OKAY button on the navigator while the Wait Node in the behavior tree is highlighted.
    TBD24.jpg
    TBD5.jpg
    TBD6.jpg
  9. Press the Action button and select the Set To Node to close the gripper.
    TBD7.jpg
  10. Edit the Set To Node by selecting it in the behavior tree and pressing OKAY.
    TBD8.jpg
  11. The signal to close the Electric Parallel Gripper is 'cmd_grip.' This should be set to "true" or 1.
    TBD9.jpg
  12. Create another 1 second Wait node by repeating steps 6 & 7.
  13. Move the arm to the pose that the arm should retract to after the pick.
  14. Create a Move-To Node in this arm pose.
    TBD30.jpg


Creating a Position in space to Wait

A new sequence should be created for the next set of actions.

  1. Press the back button to navigate back up the behavior tree. Highlight the task Sequence Node.
    TBD31.jpg
  2. Press the Action button and select "Sequence node"
    TBD12.jpg
  3. Notice that by following the above steps will create the new sequence node as the second child of the Task sequence.
    TBD33.jpg
  4. Move the arm to a new location in space that will be used to simulate holding in front of a machine. Create a Mode-To and a 5 second Wait as children of the new sequence.
    TBD14.jpg

Creating a Place Sequence

Use the same methods as performed in the above steps to create a place sequence to release the part

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After completing the place sequence, the behavior tree should look like this:

TBD34.jpg

Open the Robot Screen Menu and press Run to start the task.