Performance Analysis of Ice-Relative Upward-Looking Doppler Navigation of Underwater Vehicles Beneath Moving Sea Ice

Laughlin D L Barker,Louis L Whitcomb

doi:10.3390/jmse9020174

Abstract

This paper addresses the problem of ice-relative underwater robotic vehicle navigation relative to moving or stationary contiguous sea ice. A review of previously-reported under-ice navigation methods is given, as well as motivation for the use of under-ice robotic vehicles with precision navigation capabilities. We then describe our proposed approach, which employs two or more satellite navigation beacons atop the sea ice along with other precision vehicle and ship mounted navigation sensors to estimate vehicle, ice, and ship states by means of an Extended Kalman Filter. A performances sensitivity analysis for a simulated 7.7 km under ice survey is reported. The number and the location of ice deployed satellite beacons, rotational and translational ice velocity, and separation of ship-based acoustic range sensors are varied, and their effects on estimate error and uncertainty are examined. Results suggest that increasing the number and/or separation of ice-deployed satellite beacons reduces estimate uncertainty, whereas increasing separation of ship-based acoustic range sensors has little impact on estimate uncertainty. Decreasing ice velocity is also correlated with reduced estimate uncertainty. Our analysis suggests that the proposed method is feasible and can offer scientifically useful navigation accuracy over a range of operating conditions.

Highlights

Measurements from the selected Global Navigation Satellite System (GNSS) and One Way Travel Time (OWTT) units, were used in conjunction with the process and observation models outlined in Section 3 to estimate the state of the system using the Extended Kalman Filter (EKF) according to Table 3
This paper reports the results of a sensitivity analysis of an Extended Kalman Filter for use in navigation of underwater vehicles beneath moving sea ice using simulated sensor measurements
The effects on ice-relative vehicle x − y navigation position Root Mean Square (RMS) error and uncertainty are examined over a range of ice-deployed GNSS spacing and configurations, varying translational and rotational ice floe velocities, and ship-deployed OWTT transducer spacing

Summary

Introduction

For an extensive review of the scientific motivation and challenges, development, and use of underwater robotic vehicles designed for use in ice-covered waters, with special attention paid to the navigation systems employed for under-ice deployments, the reader is directed to [2]. The paper reviews all known under-ice robotic vehicles and their associated navigation systems, categorizing them by vehicle type (tethered, untethered, hybrid, and glider) and by the type of ice they were designed for (fixed glacial or sea ice and moving sea ice). Few methods presently exist for precision navigation of UUVs for the benthic survey and sampling operations under fixed and moving sea ice. Land-fast (fixed) ice, provides an inertial reference surface against which UUVs can utilize conventional upward-looking

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Conclusion