The MRU and SRF Aligned (I)

With increasing accuracies of positioning and multi-beam systems, alignment of the motion reference unit (MRU) is becoming increasingly important. Although most (if not all) multi-beam surveyors use the patch-test to resolve the angular offsets between the multi-beam head and the MRU, this test does not give us the angular offsets between the MRU and the ship’s reference frame (SRF). In addition to this, any misalignment between the vertical rotation axis of the MRU and the SRF (yaw-angle) will introduce cross-talk between pitch and roll.<P> The alignment of the threeaxes is also becoming increasingly important at shallower depths as we should... (read more)

2009-01-05 12:00:00

The MRU and SRF Aligned (II and III)

The alignment of the motion reference unit (MRU) is important for the accuracy of a multi-beam survey. The patch test is mostly used to solve angular offsets between the multi-beam head and the MRU; however, this does not solve all the aspects that must be taken into account. This article in two parts describes the method used by the Survey Department of the Directorate-General for Public Works and Water Management (Rijkswaterstaat; The Netherlands), which for reference purposes in this article we shall call the ‘Dutch method’.<P> As explained in Part I in theprevious issue of Hydrointernational, the alignment of the... (read more)

2009-01-05 12:00:00

Subsea 7 Receives MRU with Serial Number 5000

Kongsberg Seatex, the position reference systems division of Kongsberg Maritime celebrated a significant achievement in the development of its Motion Reference Unit (MRU) today (March 11th 2008) by presenting Subsea 7, one of the world's leading Subsea engineering and construction companies, with the MRU marked SN 5000. Martin Day, Subsea 7's Global Survey Manager, accepted the special MRU during a presentation on the Kongsberg Maritime stand at Oceanology International. Showing the company's support for this almost industry standard system, an order for two further units has been received from Subsea7. Over many years Subsea 7 has purchased significant... (read more)

2008-03-26 10:12:44

Inertial Labs to Supply STR with Motion Reference Systems

Subsea Technology & Rentals Ltd (STR, UK) has entered into a partnership agreement with USA-based Inertial Labs to distribute its innovative motion reference systems. Inertial Labs’ Motion Reference Unit (MRU-B2), along with its Enhanced Motion Reference Unit (MRU-E) and professional model (MRU-P) will be joining STR’s expanding rental pool. The Motion Reference Unit (MRU-B2), is an inertial sensor-based orientation, positioning and control solution for a diverse array of marine and subsea applications. It has been designed to meet the exacting standards for heave, surge, sway, angular rates, accelerations, heading, velocity and positioning required by maritime and hydrographic applications for any type of... (read more)

2016-10-31 09:01:43

Marine Motion Sensor

Kongsberg Maritimes has introduced a new member in its family of Motion Monitoring Units at Ocean Business 2015. The MRU 5+ MK-II is part of a range of MRUs for diverse marine applications including: motion compensation of multi-beam echo sounders, high speed craft motion control and damping systems, heave compensation of offshore cranes, dynamic positioning, hydro acoustic positioning, ship motion monitoring, ocean wave measurements and antenna motion compensation and stabilisation. The MRU 5+ MK-II uses a new sensing element (Coriolis force resonator) in the new design of integrated MEMS gyros. With less than 0.002° angle noise, and Angle Random Walk... (read more)

2015-04-18 12:03:00

Qualifying Heave Performance at Sea

Comparison of ORE MEMS-based MRU Heave Measurement with RTK-GPS

When accelerometer-based heave units were developed, there were limited options for verifying their performance at sea with a recognised standard. With real-time kinematic (RTK) global positioning system (GPS) devices, surveyors today can achieve accuracies of 2cm in altitude measurement. With the advent of small, low-cost, low-power, micro-electrical mechanical systems being employed for motion-sensing, a compact and cheaper alternative is available to measure heave. We have verified the heave of our motion reference units at sea with RTK-GPS. View Larger Map ORE Offshoreadded heavemeasurement to their pitch-and-roll motion reference units (MRU) in April 2009, which use micro-electrical mechanical system (MEMS) sensors.... (read more)

2009-06-26 12:00:00

Hydrographic Society Benelux

News Corporate Workshop 8th September 2004 Simrad BV, on behalf of the Hydrographic Society, gave a corporate workshop on 8th September 2004 entitled ‘Shallow Water Survey’. Almost eighty people attended this event held at the Rotterdam Airport hotel, which provided a good opportunity to gather information related to Innomar Technology, whose representative discussed parametric sub-bottom profilers, and Kongsberg Maritime, whose multi-beam, underwater instrumentation and motion sensors all came under review in the in the afternoon session. Companies have a good record on proven projects with quality and performance of equipment for the offshore, hydrographic and dredging market. For Kongsberg Maritime,... (read more)

2008-01-01 01:00:00

Kongsberg Seatex Motion Reference Products

At Oceanology International 2012, two Motion Reference Units from Kongsberg Maritime’s position reference specialist division, Kongsberg Seatex, Norway, have been showcased. The MRU 3 is a completely new model within Kongsberg Seatex’s 5th generation of roll, pitch and heave motion sensors. It is especially designed for heave compensation applications including real-time heave compensation of echo sounders and active heave compensation of offshore cranes. It provides heave measurements to meet IHO standards and achieves high reliability by using solid state sensors with no rotational or mechanical parts. Another new model to the fifth generation of MRUs, the new MRU E, is... (read more)

2012-04-16 10:37:23

GEUS Orders First EM 3002 Multi-beam in Denmark

GEUS – Geological Survey of Denmark and Greenland, department of Quaternary Geology, has placed an order for a dual EM 3002 system. The contract includes SIS - Seafloor Information System, Neptune, CFloor post-processing software, MRU-5, Seapath-20, SV plus-probes and training. The system is to be delivered in the beginning of July with installation and sea-trials in the mid of August. (read more)

2005-08-22 12:00:00

Imagenex Adds Sonar and Sensor Interface Relay

Imagenex has released the Model 878 high-resolution sidescan sonar which runs two sonars simultaneously on each side at different sound wavelengths for enhanced image clarity. The new DT100 Sensor Interface Relay (SIR) provides a central connection point for bathymetric sensors including sonar (1 or 2 units), GPS, MRU, gyro/heading, and sound velocity. The DT100 multibeam echo sounder has been revised. The sidescan sonar Model 878 'RGB' (triple simultaneous frequencies) has undergone a facelift and become more affordable. Both models are equipped with an optional echo sounder and a built-in orientation module as well as depth and temperature sensors. Powered by... (read more)

2013-08-23 11:06:58