Dual Arms with Wrists Calibration Example

This advanced topic assumes you have a solid working understanding of PC-DMIS, including such concepts as probe angles, calibrations, the autocalibrate command, move point commands, multiple arm mode, and other concepts.

This topic provides a typical calibration example to show the steps needed to calibrate a dual-arm horizontal machine with different extensions on the wrist and with a probe changer. After a full calibration, additional steps explain how to create two measurement routines that will automate the calibration steps so you can more quickly perform the calibration when needed. Some steps are described generally and assume that as an advanced user, you are already familiar with the underlying principles needed.

This example uses CW43L_Multiwire wrists with short, medium, and long probe extensions containing TP2/TP6 probes. Your actual procedure will differ.

Before you begin, make sure the following has taken place:

The machine has been properly compensated. This compensation data must reside in the Leitz controller for both the arms.

You understand the importance of temperature compensation.

Be sure to take into account how temperature will affect your calibration, and compensate as needed.

The coefficient of expansion of the part (or in this case the calibration sphere) is zero. For more information, see "Compensating for Temperature" in the "Setting Your Preferences" chapter.

Both arms have been properly assembled and aligned.

A technician should have corrected any possible skew that may have occurred during the assembly and mechanical levelling of the wrists. Data from this correction should have been stored in the controller in the COSDAT.

You should understand the wrist orientations on each arm. Each wrist when positioned at specific angles determines the orientation of that wrist's head compared with the machine's axes. The following example demonstrates some angles used on a PRIMA machine:

Example showing some angular positions and the orientation values for each arm

Long extensions are often useful on vertical machines and wrists. If you use a very long extension, you'll need to create a map for that extension. These machine types are highly accurate, and it takes several hours to finish a mapping on this type of machine.