How Do Tactile Probes Work?

Over the last 30 years, the tracker/SMR combo has become a benchmark for high-tolerance, portable measurements in industries from Aerospace to Automotive to Shipbuilding. But as designs and features?have grown more complex, tactile probes have become more useful to capture features both intricate and out of the tracker’s line-of-sight that otherwise require smaller SMRs or time-consuming tracker repositioning. So, with how popular these probes have become, we wanted to take a look at how they work with the tracker and how they differ from a traditional SMR to take accurate measurements.? How it Works – vProbe - API Metrology

How?Are Probes Different from SMRs?

For the purposes of this?article,?we’ll?be discussing the new API?vProbe.?vProbe?uses a traditional SMR, mounted in a larger housing with both horizontal and vertical probing locations available to reach all features on the part.?It’s?these stylus locations that start to separate?vProbe?from a traditional SMR.?vProbe?takes the tracker’s laser into its mounted SMR and reflects the beam back to the tracker from the center point.

But unlike SMR-only measurements,?vProbe?itself is performing calculations throughout the measurement process. These calculations are necessary because the tracker is not measuring points at the center of?vProbe’s?SMR; the tracker is measuring points at the tip of the probe. In order to accurately communicate this point information to the tracker,?vProbe?needs to keep track of two main data points: the length of the probe and the SMR’s position relative to the probe tip.?

vProbe?features RFID-chipped styli with lengths ranging from 50 to 500mm. The chips in these styli allow?vProbe?to instantly recognize them when they are mounted and include their distance in measurement calculations with the tracker. But the distance is only half of?vProbe’s?calculation. The SMR inside?vProbe?can move in multiple directions without the probe tip moving. This would change the SMR distance to the tracker and allow for multiple values to be measured at a single point on the part.?To compensate for this SMR movement and the angle created by the user’s hand,?vProbe?has multiple internal levels to calculate how far off of center in each direction the housing is.

This offset, combined with the length of the probe tip, gives?vProbe?an absolute position for the SMR in relation to the probe tip.?vProbe?is able to communicate this information wirelessly to the same metrology software the tracker is using.?

How Does the Probe Work with the Tracker?

Information from the tracker and probe is combined in the software to produce the absolute reported value for the part’s feature, which can then be compared to the CAD model.?vProbealso features smart buttons on either side of the housing, which can trigger single point and dynamic scan measurements, making single-operator probe measurements simpler than those of an SMR.?

The complex electronics inside mean?vProbe?requires a power source, and its swappable batteries allow for 6 hours of continuous measurement on one charge, as opposed to continuous measurements offered by SMRs.

In short, tactile probes use an SMR mounted in a housing offset from a stylus probing tip to reach intricate and out-of-sight points on a part. To compensate for this offset, smart probes calculate the length of the stylus and the housing’s angle in relation to the tip. This information is communicated to the metrology software and combined with the tracker’s measurement data to determine the absolute position of the measured point and compare it to CAD data.

To learn more about API’s new?vProbe?and schedule a demo today, write to: [email protected]