Overview

Lodestar AHRS and Lodestar AAINS systems are comprised of six sensing elements, three Ring Laser Gyros (RLG) and three linear accelerometers, running a Sonardyne developed gyrocompass algorithm with an optional AAINS upgrade.

The AHRS (Attitude and Heading Reference System) processing package is a genuine gyro-compassing algorithm capable of precise heading, roll and pitch estimation in dynamic conditions without the need for any aiding inputs or manoeuvres.

The AHRS output is available as an alignment means to an inertial navigation algorithm. Uses for the AHRS include a ship’s gyrocompass, attitude compensation for acoustic navigation systems and for survey grade multi-beam echo sounders.

The Acoustically Aided Inertial Navigation System (AAINS) takes aiding inputs from LBL and USBL transceivers as closely coupled observations in addition to aiding from DVLs, GPS and the AHRS algorithm.

Lodestar also applies a heave algorithm to the vertical motion of the unit resulting in a robust heave measurement solution. Therefore, the Lodestar product is suitable for any application that requires the accurate measurement of heading, heave, roll, pitch and with AAINS, position in a highly dynamic environment.

For a rigorous time reference the local clock can be locked to a reference clock for missions lasting several days. Applications include a secondary reference system input to a DP drilling vessel and a subsea ROV navigation system.

In addition to the 4 traditional RS485 /RS232 serial interfaces to aiding sensors and clients systems there is an Ethernet interface. This provides web browser operation, delivery of data to clients using TCP/IP based protocols as well as providing a high speed link to download the data from the mass storage.

Features & Benefits

Single IP66 rated solution for motion sensor and gyrocompass

0.1º heading accuracy unaided

<5 minute settling time

0.01º roll & pitch accuracy

5cm / 5% heave accuracy

Fast follow up speed of 500º/Sec

Subsea versions rated to 1000, 3000, 5000 and 7000 metres available

Ethernet interface

Transport approved Li-Ion battery back up as standard

Flexible power input AC or DC

On board 4GByte memory allows post processing of a 2 day mission

No dedicated GPS string required

MTBF RLG >100,000 hours MTBF Lodestar >50,000 hours

Designed and Approved to IMO Resolution A424(XI)

Technical Specifications