Hydroacoustically aided inertial navigation for joint position and attitude estimation in absence of magnetic field measurements

Abstract

When an underwater intervention vehicle is close to large metallic structures, e.g. subsea oil and gas facilities, magnetic disturbances might render magnetic field measurements biased or useless. This loss of information is critical for attitude estimation, and consequently, for the safety of the operation. In this paper, a three-stage filter for joint position and attitude estimation is developed, replacing the magnetic field measurements with hydroacoustic measurements. This solution assumes a hydroacoustic sensor set up with multiple transponders on the sea floor and 3 or more transceivers on the vehicle. The three-stage filters is shown to yield GES error dynamics of both the translational and rotational motion. The three-stage filter is shown in simulations to successfully estimate both the true position and attitude of the vehicle.

Attitude estimation by multiplicative exogenous Kalman filter

“…In Johansen and Fossen [13], a new way of using the linearized KF is presented, called the exogenous KF (XKF). This idea has been used in Johansen and Fossen [14,15] on the position estimation problem with biased range measurements, in Stovner et al [28], Jørgensen et al [16], and Stovner, Johansen, and Schjølberg [29] for underwater position estimation, and in Stovner and Johansen [27] for joint position and attitude estimation. The XKF is explained conceptually in Section 2.1.…”