A Robust Calibration and Alignment Procedure for Collocated Magnetometer and Accelerometer Sensors

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Authors
  1. Richards, T.C.
  2. Lucas, C.E.
Corporate Authors
Defence Research and Development Canada, Atlantic Research Centre, Halifax NS (CAN)
Abstract
To simplify the task of aligning three-axis magnetometers to a horizontal, vertical, and magnetic north reference frame on the seafloor, as required for ship signature measurements, a three-axis accelerometer can be rigidly mounted to the magnetometer and the measured accelerations used to rotate the data to the required reference frame. We present a calibration procedure that corrects for scale and orthogonality errors of the magnetometer, computes a cross-talk and offset model for the accelerometer, and then determines rotation angles to align the magnetometer and accelerometer axes. The key to the procedure is the design of a solenoid which creates a highly uniform magnetic field over a large volume within the solenoid. The solenoid design begins with a conventional approach using equally spaced concentric loops with the same number of turns, but then allows the current in a number of the outer loops to vary over a continuous range (as required for optimization). Then for a realizable design, the optimum ampere turns are rounded to an integer value, and the magnetic field is re-optimized by varying the position of the same loops. After construction, the solenoid itself was calibrated using a scalar magnetometer. To determine the calibration coefficients the sensors under test are placed within the uniform magnetic field at a number of nominal orientations and a very low frequency current is applied. As the procedure works with the magnitudes of the magnetic and gravitation
Keywords
magnetometer;accelerometer;calibration;alginment;solenoid;uniform magnetic field
Report Number
DRDC-RDDC-2015-N009 — External Literature
Date of publication
16 Jun 2015
Number of Pages
25
DSTKIM No
CA040725
CANDIS No
801728
Format(s):
Electronic Document(PDF)

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