Reference Position Status

The reference position must be SET unless the Offset Mode is Found Position. The workpiece, in the reference position, is the workpiece to which the robot handling positions are initailly taught.

To SET the reference position place a workpiece in the field of view. Press SNAP+FIND. Verify that the proper workpiece was properly found with the highest score in the results list. If the desired workpiece is not first in the results list, obstruct the other workpieces or temporarily modify the search window in the Locator tool, and SNAP+FIND again. Press SET to set the found workpiece as the reference workpiece.

Once the Reference Position has been set, teach the robot handling positions with the vision offsets. While the workpiece is at the reference position, the vision offset will all be near zero.

A common trick users do is to teach the robot handling positions first, move the robot out of the way, and without moving the workpiece set the reference position.

Reference position and actual position
The offset data is calculated from the position of the original workpiece, set when the reference position was taught and the current workpiece position. The position of the workpiece set when the robot program was taught is called as the reference position, and the current workpiece position is called the actual position. iRVision measures the reference position when the robot program is taught, and stores it internally. The operation of teaching the reference position to iRVision is called reference position setting.
Offset data
iRVision uses an offset frame, it becomes unnecessary to calculate the position of each point individually. In the following figure, iRVision moves the offset frame to a new position. The position of the workpiece relative to the offset frame is the same as the position of the workpiece at the reference position by moving the offset frame, it becomes unnecessary to calculate the offset data for each point individually, and teaching becomes easy. iRVision outputs the movement of offset frame as the offset data. Since the offset data is the movement of the coordinate system, it differs from the actual movement of the workpiece. Moreover, the offset data does not become an intuitive value in many cases. As the workpiece rotates and there is a large distance between the origin of the workpiece and the origin of the offset frame the difference between the offset data and the actual movement of a workpiece become large. In this case, it is not useful for the user to study the X and Y components of an offset individually. The frame offset approach is the common solution for robot guidance with iRVision.
Offset calculation by shifting a frame