Sonardyne is well known for its subsea acoustic technology and the new Lodestar is a natural extension of the product range, developed for seamless integration with the company’s LBL (Long BaseLine) and USBL (Ultra-Short BaseLine) acoustic positioning systems. It will also provide motion compensation to support operations in any sea conditions. These are likely to include platform stabilisation, dynamic positioning, buoy monitoring, subsea construction and towfish, ROV/AUV operations.

Available in surface or subsea configurations rated up to 7,000m, Lodestar is a solid state AHRS incorporating six sensing elements, three ring laser gyros and three linear accelerometers. Designed in features include 4GB of internal memory, internal power from a back-up battery, an ethernet interface to provide fast update rates, and multiple output strings that make it suitable for a wide range of applications.

The gyrocompass algorithm calculation developed by Sonardyne for Lodestar produces readings in real time for heading, roll and pitch. Because of the precision of the sensing elements used in the unit, these values can produce a highly accurate solution for each rotation in the x, y and z axis. Lodestar also provides a robust heave measurement solution by applying a heave algorithm to the vertical motion of the unit. Lodestar is consequently suitable for any application requiring the accurate measurement of heading, heave, roll and pitch in a dynamic marine environment.

By combining a motion sensor and gyrocompass in the same unit, significant advantages can be gained in relation to system calibration as the heading and motion frame share a common internal alignment axis. Lodestar is upgradeable to full Inertial Navigation System (INS), providing position, velocity, orientation, and angular velocity at high update rates.

The heading capabilities of Lodestar include a follow up speed of 500(DEGREES) per second and a settle time of about five minutes. Its roll and pitch performance includes a dynamic accuracy of less than 0.02(DEGREES) with a resolution of 0.01(DEGREES). Heave measurements are accurate to within 5cm or 5%, whichever is greater.