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Sensor alignment

In addition to the offset measurements, sensors for course and attitude are also aligned for optimum performance. Standard procedure with floating objects is establishing fixed points above the waterline for future use. In this way offsets to newly added sensors above the waterline can be measured, while attitude and heading sensors can be aligned within their specifications while the object is still afloat. The position of the motion sensor's phase centre is measured as well, regardless its position on board, again with sufficient accuracy.Pitch calibration on board of a survey vessel
Wild T2 based 400gon auto collimation target developed by StarmountainFor motion sensor alignment with the highest accuracy Starmountain has developed a new type of autocollimation target. Thanks to its design it now is possible to align motion sensors using optical tooling and autocollimation, even when perpendicular setup is not possible. These new types of autocollimation targets are based on compensatorless optical theodolites, such as the Wild T2 and Carl Zeiss Th1 and allow alignments even under floating conditions.

Still the preferred method for accurate heading sensors (or motion sensors including them) as the IXSEA PHINS remain gyro calibration based on output rather on mechanical alignment, as that is the only 100% assured alignment.

When using sensor output, proven accuracies are approximately 0.02 degrees for pitch and roll and 0.03 degrees for heading. When using optical tooling the yaw of motion sensors can be established to within approximately 0.005 degrees, eliminating cross-talk under most common conditions.
Examples of objects measured by Starmountain can be found here.

For more on this subject also see our offset surveys web site.