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.
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:
- Launch and recovery systems (LARS)
- Offshore Cranes
- Drilling draw works
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
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 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
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 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.
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.