Lodestar Hardware
Manual
Document Ref: UM-8084-101
Issue: A– Rev 8
© Sonardyne International Limited 2013
8
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About Lodestar
3.1 Introduction
Sonardyne International Limited has applied its comprehensive experience in
producing advanced and dependable marine solutions to the development of the
Lodestar Attitude and Heading Reference System (AHRS) / Inertial Navigation
System (INS).
The Lodestar is a solid-state AHRS/INS that includes three Ring Laser Gyroscopes
(RLGs) and three linear accelerometers. These inertial-grade components provide
raw data to the Sonardyne-developed gyrocompass algorithm, which uses them to
produce a full range of accurate real-time motion and attitude measurements in all
sea states.
Developed originally to provide accurate heading and attitude measurements for
Sonardyne’s family of acoustic positioning systems, Lodestar is equally suited to a
variety of other applications where the accuracy of heading and attitude
measurements is of critical importance. Lodestar can operate either as a stand-
alone AHRS or as part of an integrated system.
Lodestar is available in surface and subsea versions, where Sonardyne’s
experience with underwater acoustic navigation systems has been applied to
overcome the problems associated with conventional sensor platforms, such as
temperature shock.
Lodestar provides the following as standard:
•
industry-standard output telegrams
•
battery backup to maintain uninterrupted operation in the event of brief power
failure
•
Battery operation will last up to two hours when using a battery from a fully-
charged condition.
•
8 GB of internal memory.
•
Upgrade capability to a full Inertial Navigation System (INS) that provides
additional outputs of position, velocity, orientation and angular velocity at high
update rates.
•
0.03° secant-latitude heading accuracy.
•
0.01° roll and pitch measurement accuracy.
•
Fast follow-up speed of 500° per second.
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Single-box solution for motion sensor and gyrocompass.
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No dedicated GPS receiver necessary.
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A settling time of less than five minutes.
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Support for all industry-standard telegrams.
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Ethernet interface as standard.
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Mean Time Before Failure (MTBF) for the IMU in excess of 100,000 hours.
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Low life-cycle cost.
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Flexible mounting arrangements.
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Low current draw on start-up.
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Choice of three subsea unit depth ratings – 1000, 3000 or 5000 metres.
•
Heave measurement accuracy the greater of 5 cm or 5% of measured heave.
•
Robust heave algorithm.
•
Data output through RS232 or RS485 serial or Ethernet interfaces.
