Instrument Properties

To Access an Instrument’s Properties:

The properties for an instrument will vary depending on the class of instrument (laser tracker vs. arm vs. scanner, etc.), but the basic controls and layout is much the same. Shown below are two examples (a Leica AT960 Laser Tracker and a Hexagon Absolute arm). The Instrument index in the SA Treebar as well as the model and port are listed at the top of the dialog.

Sensor Control

The sensor control section allows you to adjust the graphic model of the instrument. For spherical devices, you can adjust the vertical, horizontal, and distance degrees of freedom. For an arm, you can adjust the rotation value for each link. Other instrument types (such as laser scanners) may not have any adjustment at all. After selecting the degree of freedom and associated value, click the Apply button to see the changes. Or, click the up/down arrows to increment the rotation value.

Scale Factor

It may be desirable to apply a scale to an instrument’s measurements to account for thermal expansion and contraction of a measured part. For example, suppose you have a nominal model that has been designed for 68°F (20°C) conditions. If you are laying off nominal features from that model on a hot day--say 95°F (35°C)--then you will want to scale the instrument’s measurements down from 95°F to 68°F so that the instrument and the nominal model are adjusted to the same temperature reference. One way to achieve this is to scale the instrument’s measurements.

When an instrument scale factor is applied, all measurements from the instrument will be scaled appropriately relative to the instruments origin. For example, an instrument observation that is normally at a radius of 100” from the instrument will be 101” from the instrument at a scale factor of 1.01. Instruments that are currently using a scale factor other than 1.0 will appear with a special yellow icon in the tree and will be listed as a scaled instrument.

Uncertainty Variables

All instruments have error in their measurements, and as a result every measurement from an instrument has some uncertainty. Each class of instrument (laser tracker, PCMM arm, total station, etc.) has different set of uncertainty characteristics. For example, laser trackers have uncertainties for the horizontal and vertical encoders, as well as an uncertainty for the distance measurement. PCMM arms, on the other hand, have an angular uncertainty for each link of the arm. Additionally, each instrument within a specific instrument class has different values for the uncertainties. The uncertainty values for a newly calibrated laser tracker in pristine condition from a manufacturer will be different from those of an old, dirty, poorly calibrated tracker from the same manufacturer.

Instrument Graphics (PCMM arms only)

PCMM arms have an Instrument Graphics button that appears directly under the Edit Uncertainty Variables button. This button calls up the Instrument Graphics dialog

SA offers the ability to manually calibrate an arm graphical model based on measurements recorded in the job file. Once calibrated this new calibration is saved in C:\Analyzer Data\Persistence. If a calibration is found for you arm SA will load it automatically when it connects.

Instrument Communication Controls

Several instrument communication controls have been added to allow users to tailor performance based upon their computer performance and instrument requirements. These include:

Additional Information