HAIN: an integrated acoustic positioning and inertial navigation

Abstract

Exploration on deeper water puts high requirements on underwater positioning for both DP operations and survey applications. Acoustic positioning systems are continuously improved to meet new requirements. Development carried out during the last years for the HUGlN AUV has brought new technology available for combining acoustic positioning with inertial navigation. Based on this the HAlN system is developed as an extension to the HiPAP and HPR systems. HAlN Position ReferenceThe HAlN system for vessel positioning is an aided inertial navigations system. The position drift that is inherent in Inertial Navigation Systems is limited by the acoustic position measurements relative to transponder(s) on the seabed. The system can be used both with SSEL or LBL position input. The HAlN provides an improved position of the vessel which both has increased accuracy and higher update rate than the original position from the acoustic measurements. This extends operational water depth and reduced battery consumption. Position output during acoustic dropout will be maintained. HAlN SubseaThe system is also available in a version for ROV positioning for survey applications. In this version the system also is interfaced to a Doppler velocity log and a pressure sensor. The complementary solutionAcoustic and Inertial positioning principles in combination is ideal, since they have complementary qualities. Acoustic positioning is characterised by relatively high and evenly distributed noise and no drift in the position, whilst inertial positioning has very low shortterm noise and relatively large drift in the position over time.The presentation at Oceans'04 will show the HAlN operational methods, benefits and accuracy figures.

Navigation and control of an AUV affected by asymmetric thruster response

“…1 The angular velocity ω n en can be defined as such velocity needed to make the navigation frame constantly aligned with the Geodetic North-East-Down configuration, while the body travels on the Earth surface…”

“…There exist different navigation system solutions involving classical Kalman filters (e.g. [1]), particle filters (see the literature review in [2], for instance) and complementary filters ( [3]) which exhibit different performances and computational efficiency. The guidance we are going to consider is a waypoint-based solution which uses cubic spline to generate a trajectory for the autopilot system.…”

A Non-singular Horizontal Position Representation

“…Examples of military usage include position calculations for radars, passive submarine sonars and active ship sonars, where the position calculations include target tracking. For navigation applications, n -vector is central for the position calculations in NavLab, HAIN (Marthiniussen et al 2004) and the HUGIN real-time navigation system (Hagen et al, 2003) and (Jalving et al, 2004). Applications include real-time and post-processing implementations in Matlab, C++ and C#, where thousands of hours of sensor data have been processed using n -vector, since 1999.…”

Surface Based Underwater Communications

“…This paper acknowledges the need for a filter that removes the channel noise n(t) and assumes a filter design similar to [2]. It is assumed that the transmitter's position is encoded in the message e(t) before being sent to the receiver, this requires the transmitter to have an integrated inertial navigational system (INS) with an acoustical aid to determine its position as demonstrated in [13], The position of the transmitting node is composed of the latitude, longitude and depth. The INS in the transmitter will be initialized before being deployed in the water; the initial position estimates will be geographically referenced.…”

“…Hence we have: log log log H z ̂ ̂ h n (13) The expression (13) is termed the complex cepstrum of the discrete signal and requires both ̂ and h n to be stable, meaning that their region of convergence (ROC) must contain the unit circle.…”