Total Acceleration (TA) is the vector sum of the accelerations due to gravity measured by each axis sensor in a ShapeArray segment. This vector sum should always be around 1 G.
If the total acceleration of a segment seen in SAARecorder (see SAARecorder 'Total Acceleration Check' section) or SAAView shows a total acceleration outside of its expected range then that is a good indication that one or more accelerometer outputs of that segment have been compromised somehow.
- Model 1 and 2 SAAF and Model 1 SAAScan - 0.93 G to 1.07 G
- Model 3 SAAF, Model 2 or newer SAAScan, all newer ShapeArrays - 0.99 G to 1.01 G
For example the sensor outputs could have been affected by a large shear deformation that damaged the wiring of the segment, or a small tear or break in the SAA could have allowed water to intrude, causing a partial short circuit to occur.
If a segment has a bad total acceleration, it cannot be relied upon for measurements of ShapeArray shape or deformation. When only a single segment is affected and is known to be within a stable zone it is often desirable to straighten or slave the segment so that it uses the tilt from the preceding segment (closer to the reference end) in calculating the ShapeArray shape.
For details on straightening or slaving segments in SAARecorder, please refer to: SAARecorder, 'SAA Setup -> Advanced -> Straighten Section of SAA' section. For SAACR_raw2data, segments can be slaved from the Settings window (SAACR_raw2data, 'Configure Conversion Settings' section) by clicking on the ‘EditSlaved’ button for the desired ShapeArray.
If a number of segments have bad total acceleration, or if the effected segment(s) are in a known deformation zone, it might be preferable to have the ShapeArray repaired or replaced. Please contact Measurand or your local Measurand distributor to arrange a ShapeArray repair or replacement.