Sonardyne Lodestar Attitude and Heading Reference System (AHRS)

Lodestar is a solid state Attitude and Heading Reference System (AHRS) and Acoustically Aided Inertial Navigation System (AAINS).

The unit comprises 3 high grade/high reliability, commercially available Ring Laser Gyros (RLGs) and 3 linear accelerometers. A Sonardyne developed gyrocompass algorithm runs in the background even when used as an AAINS.

A flexible AC or DC power input has been incorporated to facilitate surface vessel applications. With the battery back up capability supplied, the unit is able to continue running the AHRS and AAINS algorithm during vessel 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 Sonardyne SPRINT and DP-INS systems. It directly interfaces to aiding sensors such as USBL or LBL transceivers, a DVL, a GNSS receiver, a pressure sensor and a sound speed sensor (SSS).


  • Single box solution for motion sensor and gyrocompass
  • 0.04 to 0.1° secant latitude heading accuracy
  • 0.01 degree roll and pitch accuracy
  • 5 cm / 5% heave accuracy
  • Fast follow up speed of 500/Sec
  • Available in surface and subsea versions rated to 1000, 3000, 5000 metres
  • Ethernet interface
  • Transport approved Li-ion battery back up as standard
  • Flexible power input AC or DC
  • On board 8 GB memory (Expandable to 32 GB)
  • MTBF Inertial Sensors (RLG and Accelerometer) > 400,000 hours



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