In this application video, a 2-cam (16 Mpx) MSpeedDIC system is used to measure the displacement & velocity
of a rotating/turning spindle.
The projection calibration is performed first by rotating the stereo rig (whilst keeping the cameras and lenses
fixed) away from the specimen. The 10mm double-sided calibration target is automatically recognized in the
Istra4D V4.11 software via it’s QR-code, which entails information about the grid spacing, std. tolerances, and
front/rear properties (such as thickness, which is used for double-sided biplanar setups). The projection parameters
are computed live with feedback. Users can easily manoeuvre & orientate the target based on the visual indicators.
In the test measurement setup, a real-time overlay of the speckle pattern quality can be seen, indicated the standard
deviation with respect to a selected facet/subset size. The Region-of-Interest (RoI) is reduced in the height direction,
so the standard framerate of 283 Hz at full resolution, can be increased to 1000 Hz to capture the rotation of the spindle.
In Istra4D V4.11, the RoI can be adjusted pixel-wise allowing the maximum resolution to be achieved for the desired
frame rate. A ringbuffer recording is performed at 1000 Hz, for which a pre/post trigger is executed when the spindle
rotates into the FoV of the cameras – only 300 frames are actually captured for the measurement.
Point tracking is then performed of the spindle, whereby two facet/subset markers are selected by the user on the image.
These are then correlated using the facet/subset correlation algorithm – point-wise. Plots of the path trajectory of the
point markers can be seen. The increasing Z-displacement (mm) from the two markers indicate that the spindle is slowly
standing upright (towards the direction of the cameras). From the plot of the total displacement, velocity and acceleration
of the two markers it can be seen that spindle is slowly wobbling (out-of-sync), which is visible from the separation of the
two line curves. Additionally, from the acceleration plot it seems that the rotation of the spindle is slowing down.
Motion analysis of a turning spindle using the MSpeedDIC system in Istra4D V4.11
To learn more about how Dantec Dynamics can help you solve your testing challenges, contact us today.
