How is data filtering applied in motion reference units?
Data filtering is a critical process within Motion Reference Units (MRUs) designed to refine raw sensor measurements by removing noise and isolating the true motion components. At Norwegian Subsea, our MRUs utilize advanced sensor fusion algorithms and Kalman Filter algorithm that intelligently process data from state-of-the-art MEMS accelerometers and gyroscopes.
These sophisticated algorithms act as highly optimized filters, effectively distinguishing between vessel motion and unwanted noise or vibrations. This ensures the delivery of exceptionally accurate and stable measurements for Roll, Pitch, Heave, Yaw, Surge, and Sway in real sea conditions with irregular waves and coupled motions.
The quality of data filtering directly impacts the performance and reliability of systems relying on motion data. Our robust filtering techniques are validated in real sea conditions, providing the high-fidelity output required for demanding applications such as 3D motion compensated gangways, sonar motion compensation, Dynamic Positioning (DP), Active Heave Compensation (AHC), helideck monitoring (HMS) and much more.
While the internal filtering processes are complex, Norwegian Subsea MRUs are designed for ease of use. The filtered data is provided through various standard protocols, and users can access configuration settings via a user-friendly web interface, ensuring seamless integration and optimal performance with minimal setup.
Related products
Usage area
IP 65
Connectors
RJ45 or RJ50
Roll & Pitch accuracy
- 3000±0.05°
- 6000±0.02°
- 9000±0.01°
Heave accuracy
5 cm or 5.0%
Usage area
50 m depth, IP 68
Connectors
Lemo or SubConn 8 or SubConn 16
Roll & Pitch accuracy
- 3000±0.05°
- 6000±0.02°
- 9000±0.01°
Heave accuracy
5 cm or 5.0%
Usage area
6000 m depth
Connectors
SubConn 8
Roll & Pitch accuracy
- 3000±0.05°
- 6000±0.02°
- 9000±0.01°
Heave accuracy
5 cm or 5.0%
Usage area
Hazardous areas
Connectors
Pigtail cable
Roll & Pitch accuracy
- 3000±0.05°
- 6000±0.02°
- 9000±0.01°
Heave accuracy
5 cm or 5.0%
Further reading
MRUs for vessel performance optimisation in focus at Europort 2025
Research Project to Test Value of MRU Data for Vessel Performance and Carbon Reduction
Advanced motion compensation for sonars introduced at Ocean Business 2025
Related questions
- Read the full answer
The MRU Marine is IP-68 rated with Lemo connectors and LEDs. The Marine SW supports 50m depth, uses SubConn connectors, and comes in two versions differing by available output combinations.
- Read the full answer
Inclinometers offer basic static tilt readings, Roll & Pitch Sensors suit moderate motion, while VRUs provide precise roll and pitch in dynamic conditions. Choose based on motion complexity, accuracy needs, and budget.
- Read the full answer
Yes, the MRU supports heave output (position, velocity, acceleration) at two remote points, plus a third at the vessel's centre of gravity. This allows one MRU to serve multiple applications, like heave-compensated winches.
Related applications
Helideck Monitoring
Accurate measurement of roll, pitch, and heave motions is crucial for assessing the safety of helidecks during helicopter landing and take-off operations.
Dynamic Positioning
Dynamic positioning (DP) of vessels necessitates roll and pitch compensation of the GNSS antenna to ensure accurate positioning of the ship's control point.
Hydrography
Accurate measurements of roll, pitch, and heave are crucial for achieving optimal results when compensating multibeam echosounders for vessel motion.
Active Heave Compensation
Accurate measurement of vertical motion at the crane tip or winch is crucial for the operation of Active Heave Compensated (AHC) cranes and winches.
Motion Compensated Gangways
Accurate measurements of all 6 degrees of freedom are essential for the automatic motion control of gangways.
Riser Monitoring
The NORSUB Subsea MRU is specifically designed to provide highly accurate measurements of roll, pitch (inclination), and lateral motions in risers.
Wave Radar
Accurate heave measurements play a vital role in compensating for Wave Radar measurements when installed on ships or other floating vessels.
Ship Motion Monitoring
Precise motion measurements are essential for vessel digitalisation, supporting fuel optimisation, route planning, cargo safety and structural health.
Floating Wind Turbine Control
For floating offshore wind turbines, precise measurement of wind mast roll and pitch motion caused by waves is crucial.
Wind Turbines
Accurate and precise motion monitoring is crucial for wind turbine towers to ensure structural integrity and optimise performance.
Floating Wind Base Motion Monitoring
Monitoring the movements and structural integrity of floating wind foundations, including both the base and turbine, along with the anchoring system, is crucial.
Offshore Fish Farms
Offshore fish farming presents unique challenges, requiring continuous remote monitoring of all onboard systems, including roll, pitch, and heave motions.
Stabilising Fins
Stabilising fin and roll damping systems rely on motion sensors to accurately measure the roll motions of a ship.
Wind Lidar Buoys
Metocean buoys, lidar buoys, and other instrument/sensor carrying buoys, need reliable motion measurements to motion compensate pay load sensors, or to collect motion data for post processing.
BOP Monitoring
Accurate motion sensors play a crucial role in the structural monitoring of Blowout Preventers (BOPs), enabling the measurement of inclination and lateral displacements.
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