Stop Using DGPS!

The Unsuitability of Non-centimetric Positioning for Shallow-water MBES Surveys
High-resolution multi-beam echo sounder (MBES) surveys should not be conducted where the uncertainty of the horizontal positioning system is larger than the nadir footprint of the MBES at the mean survey depth. In depths of 100 metres, the horizontal component of the nadir footprint of a 0.5 degree by 1.0 degree MBES, is an ellipse whose minor axis is approximately 0.9m, and approximately 0.09m at 10m depth. Regardless of the International Hydrographic Organization (IHO) Special Order Specification that allows for non-centimetric level horizontal positioning, such as Differential GPS (DGPS), the results are unacceptable for high-resolution shallow-water surveys, especially where feature... (read more)
2012-11-22 02:55:10

Error in GNSS Augmented Heading Systems: Influence of Attitude

The Effect of Antenna Height Difference on Heading Quality
My earlier articles on the alignment of motion reference units (MRU) with the ships reference frame (SRF) did not cover the calibration of GNSS augmented heading systems. Although the alignment can be done in the same way as mentioned in the previous articles, GNSS augmented heading systems need special attention regarding their installation. This article will show that the accuracy of these systems may be seriously affected by the vessel’s attitude if the antennas are not installed at the same mutual height above the X/Y plane of the SRF. The more accurate ROVINS (0.05° x SEC(LAT), which is the accuracy... (read more)
2014-10-15 02:18:48

Underwater Inertial Navigation

Advanced Navigation has announced the release of its Sublocus underwater navigation system. This is an underwater inertial navigation system featuring north-seeking fibre-optic gyroscopes and accelerometers with a GPS receiver and pressure depth sensor. These are fused together in Advanced Navigation's fusion algorithm to deliver positional accuracy of 0.08% of distance travelled. The systems also provide highly accurate roll, pitch, heading, heave, depth and altitude. Sublocus is also available with an integrated RDI Workhorse Navigator DVL for combined acoustic and inertial navigation in the one product. Both models are supplied with a subsea GPS antenna and are rated to 3,000 metres... (read more)
2013-05-22 02:48:34

SBG Releases Navsight Marine Solution

At this year’s Oceanology International in London, UK, SBG Systems released the Navsight Marine Solution, a full high-performance inertial navigation solution designed to make surveyors’ tasks easier in both shallow and deep water. Navsight Marine Solution integrates the latest generation of gyroscopes, accelerometers and GNSS receivers. Navsight provides high-performance motion and navigation data as well as a real-time heave accurate to 5cm. To allow surveying when wave frequencies are large or complex, the solution comes with a delayed heave feature. If higher performance is required, the surveyor can count on Qinertia, SBG’s INS/GNSS post-processing software. New calibration procedure for easy installation... (read more)
2018-03-20 11:25:57

Dual Antenna GNSS Inertial System

SBG Systems, France, adds a new inertial system to its Ekinox Series. With integrated Dual Antenna GPS + GLONASS receiver, the Ekinox-D is a ready-to-use Survey Grade inertial navigation system which provides consistent true heading (0.05°).              The Survey Grade Ekinox-D embeds a Dual Antenna L1/L2 GNSS receiver to deliver more robust heading and position, while increasing satellite reception availability. Ekinox-D is an integrated system. GNSS data and inertial information are fused by an Extended Kalman Filter (EKF) to improve data integrity. This computation allows the system to achieve 0.05° Roll, Pitch, and True Heading;... (read more)
2013-07-26 03:00:34

Louis Dreyfus TravOcean Orders Two Saab Seaeye Leopards

Specialist submarine cable installation company Louis Dreyfus TravOcean, France, has ordered two Saab Seaeye Leopards for touchdown monitoring and support. The pioneering Leopard work vehicle, with its 11 thrusters and iCON intelligent control system, will provide TravOcean with a stable work platform that is unrivalled amongst ROVs – particularly in strong currents. Greater flight stability under variable loads is delivered by the iCON system - including pitch and roll stabilisation – to give stable flight even with large tools and sensors deployed. ICON independently manages each device on the vehicle, including auto redundancy to keep the ROV working even with multiple equipment... (read more)
2016-01-28 09:30:48

Multibeam Echosounder for Medium to Deep Water

The RESON SeaBat 7160 multibeam echosounder has been developed for marine exploration, seafloor habitat mapping and hydrographic charting in medium to deep water (3 to 3,000m). Equipped with X-Range, it provides improved system immunity to external noise. The system can operate in water depths of between 3 to 3,000 metres, offering up to 512 high-density equidistant beams with a selection of coverage modes including features such as variable and steerable swath, together with real-time pitch and roll stabilisation maximising useable swath and performance. The SeaBat 7160 also provides the collection of high-density water-column data all wrapped up in a processing... (read more)
2013-01-18 10:17:57

Zupt and Sagem Working Together

Zupt, USA, has entered into an agreement with Sagem (Safran) for the development of the subsea hydrographic and oil & gas market for the Sagem BlueNaute product range. This will include standard subsea heading, pitch, roll and heave products as well as aided inertial options (USBL smoothing and Sparse LBL) to be combined within the subsea BlueNaute products. BlueNaute is based on hemispherical resonator gyros (HRG), a patented Sagem (Safran) technology that was initially used in spacecraft. This new‐generation inertial navigation system is already used in aerospace, which has very demanding reliability requirements. BlueNaute has been developed to be fully... (read more)
2014-03-12 01:05:01

Vessel Motion Monitoring Systems for Wind Farms

OSIL, UK, has announced the launch of a Vessel Motion Monitoring System (VMMS), a system designed to monitor motion of a vessel in order to increase safety of transfers during offshore wind farm operations. With a second generation 6 DoF (Degrees of Freedom) motion sensor, the Vessel Motion Monitoring System monitors safety thresholds for heading, heave, pitch, roll, sway and yaw. This portable, battery powered monitoring system has a removable hard disk for data retrieval, and is programmed to display a red signal to indicate when it is unsafe to transfer because safety thresholds have been exceeded. The Vessel Motion... (read more)
2012-11-02 09:25:36

AC-ROV Concept Vehicle

Ac-cess and their engineering partners at All Oceans (UK) have been researching, developing and testing materials and components leading to development of the AC-ROV concept video camera and sensor platform. This has six thrusters, all identical, to give the operator all the viewing control that will ever be needed. Four full-bore vectored horizontal thruster units give equal forward, sideways and pan control, whilst two vertical units give powerful up, down and pitch control. A one handed (left or right) 5-axis controller makes for a very simple and versatile operator interface. Flight Freeze is a further feature that may be selected,... (read more)
2004-03-03 12:00:00
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