Overview

Lodestar is a solid state Attitude and Heading Reference System (AHRS). The unit comprises of six sensing elements, three Ring Laser Gyros (RLG) and three Linear Accelerometers, running a Sonardyne developed gyrocompass algorithm.

The gyrocompass calculation produces readings in real time for heading, roll and pitch of the unit / vessel. These values, due to the high precision of the sensing elements used, can produce a highly accurate solution for each rotation in the x, y and z axis of the AHRS unit.

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 and pitch in a dynamic environment.

In most applications the Lodestar is an ideal replacement for the motion sensor and gyrocompass package, due to its dynamic capability and fast spin-up time.

Ultra Short BaseLine (USBL) systems calculate the position of a subsea target by measuring the range and bearing from a vessel mounted transceiver to an acoustic transponder fitted to the target. In order to achieve the highest levels of positioning accuracy, Lodestar provides the acoustic system with a precise measurement of the heading, roll and pitch of the transceiver. The USBL system is then able to process these measurements and then compensate for them in the software.

Systems such as multibeam echosounders, side scan sonars and synthetic aperture sonars require extremely accurate measurement of vessel dynamics in real-time. Lodestar is designed to meet this demanding requirement by providing the survey system with high accuracy heading, heave, roll and pitch observations.

This enables users to maintain the quality of their survey data under all operating conditions by compensating for vessel motion during data collection. Depending on the application, users can select between surface or subsea versions of Lodestar. These options allow the optimal installation arrangement to be achieved on all types of vessel, ROVs and towfish.

The prime function of a Dynamic Positioning (DP) system is to allow a vessel to maintain its position and heading despite the effects of the wind, waves and current.

Lodestar constantly measures the heading, roll and pitch of the vessel and then outputs this in real time to the DP desk via its RS232/ 485 serial or Ethernet interface. In this application, Lodestar is an ideal replacement for the vessel’s separate motion reference unit and gyrocompass due to its capability in highly dynamic marine environments and its fast spin-up time.

Features & Benefits

Compatible with Sonardyne acoustic positioning products

Single box solution for motion sensor and gyrocompass

Choice of surface or subsea versions with depth ratings of 1,000 / 3,000 / 7,000 metres

Fast follow up speed of 500º/Sec

Ethernet interface

Battery back up as standard

Flexible power input AC or DC

On board 4GByte memory

No dedicated GPS string required

MTBF RLG >100,000 hours

MTBF Lodestar >50,000 hours

Low current draw on start-up

INS Ready

Technical Specifications