Lodestar is a solid state Attitude and Heading Reference System (AHRS) and Acoustically Aided Inertial Navigation System [AAINS]. The unit is comprised of 3 high grade, high reliability, commercially available, Ring Laser Gyros (RLG) and 3 accelerometers. A Sonardyne developed gyrocompass algorithm runs in the background even when used as an AAINS.

Lodestar AHRS can be supplied to suit subsea applications at any depth. With the supplied battery back up capability, the unit is able to continue running the AHRS and AAINS algorithms during vehicle power brown-outs. The Lodestar AHRS algorithm outputs precise heading, roll, pitch and heave estimation in dynamic conditions without the need for external aiding inputs or vessel manoeuvres.

Lodestar is the core component in any Sonardyne AAINS system. It directly interfaces to aiding sensors such as a USBL or LBL transceivers, a DVL, a GNSS receiver, a pressure sensor and a sound speed sensor (SSS).

• Single box solution for motion sensor, gyrocompass and AAINS
• 0.04 to 0.1° secant latitude heading accuracy (gyrocompassing)
• 0.01° roll and pitch accuracy
• 5 minute settling time
• 5cm / 5% heave accuracy
• Fast follow up speed of 500° / sec
• MTBF inertial sensors (RLG and Accelerometer) 400,000 hours
• Choice of depth ratings: 1,000, 3,000 and 5,000 metres
• Surface version available
• Transport approved rechargeable Li-ion battery back up as standard
• Minimum internal memory of 8 GB (expandable to 32 GB) allows post processing of a 2 day mission
• Ethernet interface
• AAINS capability

• An optimised USBL system: The directly coupled precise attitude data complements the precision of advanced USBL systems
• As a precise position input to DP systems using AAINS, a USBL system and one or more seabed reference beacons for operations in excess of 2000m
• As a positioning system for an ROV, aided by a combination of position estimates from a topside USBL system, vehicle mounted DVL, pressure, sound speed and LBL transceiver
• Multi-beam Surveys