SPRINT is an acoustically aided Subsea Inertial Navigation system for subsea vehicles. SPRINT makes optimal use of acoustic aiding data from acoustic USBL and LBL positioning and other sensors such as Doppler Velocity Log (DVL) and pressure sensors. This improves position accuracy, precision, reliability and integrity while reducing operational time and vessel costs. The system extends the operating limits of Ultra-Short BaseLine (USBL) and can dramatically improve the operational efficiency of Long BaseLine (LBL). The new third generation SPRINT unit offers power pass-through to aiding sensors, reducing cabling and interfacing complexity.
SPRINT INS shares the same hardware platform as Lodestar AHRS and is a combined AHRS (Attitude Heading Reference System) and AAINS (Acoustically Aided Inertial Navigation System). Running both the AHRS and INS algorithms concurrently allows inertial navigation to start or restart instantaneously on receipt of a position update as the AHRS seamlessly provides orientation to the INS on start-up. This avoids the lengthy ‘alignment’ period common to other INS systems. Thereafter, the separate AHRS and INS computed orientation are autonomously monitored as an indication of system health.
All AHRS and AAINS computations are performed within the Lodestar, making the system robust and resilient to communications issues. Lodestar maintains a rolling 15 day backup of all real time navigation and raw data on an onboard SD card which can be retrieved if required. Coupled with concurrent logging of all data by the topside software, data integrity is ensured.