Sonardyne’s Sprint is an acoustically aided inertial navigation system (INS) system for subsea vehicles where accuracy and precision in any water depth is of critical importance. 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. The system extends the operating limits of Sonardyne’s positioning system and can dramatically improve the operational efficiency of these systems.
INS is inherently self-contained, robust with very good short term accuracy but can drift over time. Therefore the INS is aided with complementary acoustic positioning to provide long term accuracy and robustness. The additional integrity offered by inertial integration significantly reduces operational delays during periods of challenging subsea acoustic conditions such as aeration and noise. The precision and update rate of the output allows greater subsea vehicle control and is suitable for ROV and AUV positioning.
|Precision||2-3 times improvement in precision over ‘raw’ USBL*|
|USBL and DVL Aided|
|Precision||4-6 times improvement in precision over ‘raw’ USBL*|
|* INS also provides improvements in short term accuracy through rejection of outliers. INS will not resolve long term inaccuracy of the USBL system (e.g. systematic errors)|
|Accuracy||< 0.1% position error for distance travelled (e.g. <1 m error after 1 km travelled)|
|LBL and DVL Aided|
|Accuracy with 1 transponder||< 0.2% distance to transponder (**)|
|Accuracy with 2+ transponers||Centimetre level (dynamic) accuracy similar to the accuracy of conventional (static) LBL but with much enhanced robustness to loss of acoustics. (***)|
|** Vehicle dynamics required
*** With good geometry and excluding effect introduced by errors in: transponder position/depth and sound speed - with careful operation these can all be minimised