Define an Operation Position Using Cumulative Snap

You can use the Operation Definition and Cumulative Snap capabilities for a quick and accurate positioning of a product relative to a resource.

Note: In the Operation Definition capability, the product is positioned relative to the resource that realizes the selected operation.

Before you begin: The purpose of the scenario is to position an engine assembly on two locating pins on a palette on a given station in an assembly line. To reproduce this scenario, open a PPR Context similar to the one used here and start Equipment Allocation.
See Also
About Operation Position
Defining an Operation Position
  1. Right-click the general operation in the tree and select Operation Position > Define Position.


    The Define Position dialog box appears.

  2. Select the palette resource.
    The image below shows how the two holes on the base of the engine assembly are to be positioned on the two locating pins.



  3. Use the Robot to move the engine assembly vertically above the palette, so that it is at a level above the top of the locating pins.
  4. In the Define Position dialog box, click Cumulative Snap.
    The Cumulative Snap dialog box appears. It comprises:
    • A list of options for specifying the type of geometry to use in the snap
    • Two commands for inverting the snap direction by a 180 degree rotation of the U-axis or V-axis.
  5. Select Arc center from the drop-down menu, and select the first hole on the base of the engine.
  6. Select Line only from the drop-down menu, and select a locating pin on the palette.
  7. Use the Robot to move the engine so that the center of the hole and the axis of the locating pin are aligned.
    The first constraint is defined.
  8. Select Arc center from the drop-down menu, then select the second hole on the base of the engine.
  9. Select Line only from the drop-down menu, and select the other locating pin on the palette.
  10. Use the Robot to move the engine so that the center of the second hole and axis of the second locating pin are aligned.
    The second constraint is defined. The first constraint is also respected.
    Note: The holes are aligned with the locating pins, but the engine is not yet lying on palette.
  11. Select Plane only from the drop-down menu, then select the base of the engine.
  12. Use the Robot to move the engine so that it lies on the palette, and is positioned using the locating pins.
    The third constraint is defined. The second and third constraints are also respected.



  13. Close the Cumulative Snap dialog box. In the Define Position dialog box, click OK to define the new operation position.
Alternatively, you can use the Snap Product on Resource command.
  • The local mode enables you to move the Robot separately from the assembled product, allowing precise positionning of the Robot origin.
  • The global mode enables you to move the Robot and the assembled product allowing precise positioning relative to a resource.

The Snap Product on Resource command inhérits the same capablities as the Snap command. For more information, see Simulation:Virtual Factory: Plant Layout Design: Smart Snapping Resources: Snapping Products or Resources.

Note: When using the Cumulative Snap or Snap Product on Resource commands, only the assembled product moves while the resources remain fixed. It is only at the end of the action that the resources recover their potential position relative to the assembled product.