Measurand: Correction of Rotation Effects Sponsored

Measurand Inc. is pleased to introduce some corrections of rotation effects in its SAAView software.

Few intended vertical installations are perfectly vertical, and some are purposely slanted. SAA, like most inclinometers, has X and Y tilt sensors in each segment. Any slight rotation of the SAA about its long axis, when that axis is not vertical, will shift some of the tilt from X to Y and vice-versa. The change in X and Y will in general not be identical. If one changes as a sine function of the rotation, the other will change as a cosine. This has the nasty effect of looking like deformation, or even worse, like drifting signals, typically unequal in X and Y. A sub-degree rotation of a significantly slanted SAA can look like centimetres of deformation. But it is fully correctable!

A new utility in our converter program, SAACR_raw2data (Beta Version), and diagnostic utilities in our viewer program, SAAView (Beta Version), enable automated correction of one-time or progressive rotation effects. The principle is simple: Pure rotation changes the sharing of X and Y tilts, but not the magnitude sqrt(X^2 + Y^2). This is easiest to visualize as a vector with unchanging magnitude, but slightly-changing azimuth. The anti-rotation algorithm looks for any such vector along the SAA and corrects its azimuth. This is particularly powerful and safe, because only the azimuth is changed, not the tilt magnitude. The before/after result is shown in the figure. What was a very large apparent and progressive deformation is completely gone.

Find more details in Measurand's Newsletter here!