Oriented placing

When a bin picking trajectory is received, alongside it additional data are transferred to the robot controller that can be used for the oriented placing of the picked object. These data describe the exact configuration of the tool point and gripping point used for grasping the picked object. By defining a placing procedure for every possible grasping configuration it is possible to achieve the oriented placing of objects.

A grasping configuration is defined by 3 variables (placing data):

  • Tool point invariance The invariance of the tool point used for grasping the picked object. If the tool point invariance is disabled, the value is always 0.

  • Gripping point ID The ID of the gripping point used for grasping the picked object.

  • Gripping point invariance The gripping point invariance used for grasping the picked object.  If the gripping point invariance is disabled, the value is always 0.

When the tool point has 2 invariances and 3 gripping points are defined for a picked object with each having 4 invariances, there is a total of 2 x 3 x 4 = 24 possible grasping configurations.

It is necessary to teach a placing position for every grasping configuration. However, any change in the definition of the tool point / gripping points will render those taught positions invalid. If possible, it is recommended to teach only a minimum required base positions and use the received placing data to calculate the final transformation (offsetting).

Note: For a cylindrical object with a gripping point lying on the axis of the object’s symmetry (example), it is necessary to have the invariances enabled to be able to grasp the object from multiple sides. However, the chosen invariance is not relevant and it is sufficient to use a single placing position for all invariances of the gripping point.

As mentioned above, these placing data (variables) are received with the bin picking trajectory when the procedure Receive trajectory is successful. See the description of the procedure inside the integration guide for a particular robot brand to see how to access the placing data.

Tip: To force a gripping point (or its invariance) to be used for the purpose of teaching a placing position, temporarily disable the rest of the gripping points (invariances). The same applies to tool point invariances.