Multibeam Echo Sounders-IMU Automatic Boresight Calibration on Natural Surfaces

ABSTRACT

This paper details a new boresight calibration method for multibeam echo sounder systems This method is based on an automatic data selection algorithm, followed by a boresight least squares adjustment This method, called MIBAC (MultiBeam-IMU Boresight Automatic Calibration), takes in input overlapping survey strips following a simple line pattern over a regular slope. We first construct a boresight error observability criterion, used to select automatically the most sensitive soundings to boresight errors. From these soundings, we perform a 3D adjustment of the boresight angle, thus taking into account the coupling between angles. From a statistical analysis of the adjustment results, we derive the boresight angle precision. Numerical results obtained with four different multibeam echo sounder systems are presented and compared to those of a patch test calibration method. Finally, we demonstrate the performances of MIBAC through a standard deviation along the surface normal approach computed by principal component analysis.

KEYWORDS:

• Boresight
• calibration
• inertial measurement system
• multibeam echo sounder

Notes

¹ We shall see that the size of the boresight estimation problem is 3P + 3, where P is the number of selected surface elements.

² Irregular areas are indeed not favorable to boresight calibration due to the fact that sampling error can be superimposed to boresight errors, causing boresight estimation bias (Seube et al. 2015).

Additional information

Funding

This research work has been in part supported by SHOM (Service Hydrographique et Océanographique de la Marine, France), under contract NOCALIT/Calibration.