Transponder Net Self Calibration Algorithm

In operating an autonomous vehicle around a submerged structure it is often necessary to position the vehicle within 5 cm. Since the positioning accuracy of an acoustic navigation system relies on a precise knowledge of the transponder locations it is vital to calibrate the transponder net before sensitive tasks are undertaken. Complete calibration of some nets could require from hours to days resulting in serious delays in the mission and increased the costs. A calibration algorithm has been developed and implemented which requires a set of slant ranges and vehicle depths generated by a survey path of the net along with an initial guess of the transponder positions. The self-calibration algorithm uses an iterative least squares process which converges to the correct transponder coordinates even in the presence of modest errors in the measured ranges.