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Motion reference unit applications

A motion reference unit for multiple maritime applications

KONGSBERG's MRUs have a proven record of installations in various applications, demonstrating their ability as a leading motion sensor in the maritime sector. With a wide range of models meeting diverse requirements for accuracy and precision, KONGSBERG's MRUs have become the de-facto standard sensor for attitude determination. Due to their design, data output possibilities and accessories, the MRUs are easy to deploy and implement in a wide variety of maritime operations.

AHC Crane

Active Heave Compensation systems for offshore cranes require data on heave motion of the crane tip. Real-time output of heave amplitude, velocity and acceleration at the crane tip is essential for precise heave compensation. MRU roll and pitch measurements are used to transfer the heave motion from the MRU mounting location to the crane tip point. The winch control system uses the crane tip heave measurement to winch in or out wire to keep the load in calm position unaffected of the vessel heave motion. This ensure safe and efficient offshore crane and wire tensioning operations.

Active heave compensation applications that can benefit from MRUs include:

  • Winches
  • Launch and recovery systems (LARS)
  • Offshore Cranes
  • Drilling draw works
  • Cranes

Motion compensation of echo sounder

Seabed mapping applications using multi-beam echo sounders require the input of roll, pitch and heave measurements to compensate for the vessel motion in depth measurements. Multi-beam systems with wide swathe width require accurate attitude measurements to ensure minimum depth errors in the outer beams.

Vessel motion monitor

Vessel motion or structural monitoring applications

For vessel motion or structural monitoring applications, the MRU can output angular and linear motion variables in different frames (body, heading and geographic) at several different points on the vessel.

Read more about VMM.

Helideck Monitoring System

Helicopter monitoring of roll and pitch

Helicopter operations on moving helidecks require monitoring of the roll, pitch, inclination and heave motion in the helideck’s centre. These measurements are sent to the helicopter operator prior to take-off from the shore station.

Read more about HMS

Dynamic positioning

All position reference system outputs in a DP system have to be transformed to a common reference point on the vessel. To achieve this, the MRU roll and pitch motion measurements have to be used.

Motion damping systems on high speed crafts

Motion damping

Motion damping systems or ride control system require the input of roll / pitch angle and angular rate measurements to the foil control system. The MRU outputs these variables with minimum latency and at a high output rate.



Stabilisation applications

Telecommunication antenna stabilisation

Telecommunication antennas mounted high up in the vessel mast often require roll and pitch compensation of the radio beam. The required measurements to achieve this are available using the MRU.

Hydro acoustic positioning

Hydro acoustic positioning is used as a positional reference for DP systems. It is achieved by measuring the distance and bearing from transducers mounted on the vessel hull to transponders on the seabed. To obtain a stable and noise-free positional measurement, the vessel motion has to be compensated for – undertaken using the MRU.

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