A calibration of SSBL acoustic positioning system in the ocean

In recent years, precise underwater observations have been performed by autonomous underwater vehicles (AUVs). The super short baseline (SSBL) method is often used to position the vehicle because of its simplicity and efficiency of the operation. Then more accurate positioning by SSBL is requested. The advantages of the SSBL method are the simplicity of the operation and the time efficiency. However, the SSBL is not accurate. In this paper, a calibration of the SSBL acoustic positioning system in the ocean is studied. In general, there are random error and systematic error in a measurement system, and the cause of the systematic error is modeled and calibrated for more accurate measurement. In the SSBL method, the error of the attitude of the hydrophone array, which is sensed by a motion sensor, is typically calibrated. Error of the attitude in the hydrophone array, We estimate the calibration that starts in the straight line and the calibration that starts in the circumference and the attitude in the hydrophone array is estimated by the technique for the combination and settling systematic error. And, it was confirmed to be able to estimate the attitude in the hydrophone array by the accuracy of about 0.1 degrees in the verification by the simulation.