Bounding Box / Virtual Box

From CPR Wiki
Jump to: navigation, search

In order to avoid collisions of the end effector with sourrounding objects, a bounding box can be established for the robot (or rather the end effector) to operate in: If the end effector is moved outside the boundaries of the box, CPRog will produce a warning and the movement of the robot will stop. Subsequent to a collision with a virtual wall, the end effector can be moved back into the box but not further out to avoid any real-world collisions.

The box is set up in the absolute coordinate system of the robot. The origin of that coordinate system is at the base of the robot below the center of the first joint.

The unit of the bounding box parameters is millimeters. The default setting is:

  • x: -4000 / +4000
  • y: -4000 / +4000
  • z: -4000 / +4000

This is a bounding box centered around the origin of the coordinate system, extending 4000mm to the left, right, front, back, up and down.

It might help to play around with these settings to get an understanding of how the bounding box works. We found it useful to try these two examples first:

Example: Do not collide with table

If the robot is mounted on a table, one could, for example, limit the movement of the end effector in the z axis to 100mm above the table by entering the following box parameters:

  • x: -4000 / +4000
  • y: -4000 / +4000
  • z: +100 / +4000

This would prevent the robot colliding with the table. It would stop 100mm above the table.

Example: Stay in corridor

To restrict the robot movement in y direction, e.g. to prevent collisions, one could limit the y movement to +/- 200mm from the origin.

  • x: -4000 / +4000
  • y: -200 / +200
  • z: -4000 / +4000