What sensor systems are used in ROV seabed mapping?
Accurate seabed mapping using Remotely Operated Vehicles (ROVs) relies heavily on precise motion compensation of the sonar as well as sensing of the vehicle's movements. Why you need motion compensation of your sonar system?
- Accurate Seafloor Mapping – Without proper motion
compensation, vessel movement can distort
sonar readings, leading to incorrect depth measurements
and unreliable bathymetric data. - Elimination of Data Gaps – Uncompensated motion
causes inconsistencies in sonar returns, resulting in
gaps or misaligned sonar images, making it harder
to detect underwater features. - Improved Target Detection – Whether for shipwreck
hunting, fish-finding, or subsea infrastructure
monitoring, stable motion data ensures clear,
high-resolution sonar images. - Avoid repeated surveys and extensive post
processing – High-quality motion compensation
ensures high-precision sonar results in real-time
Why Choose Norwegian Subsea MRUs for Sonar Motion Compensation?
- Industry-Leading Motion Accuracy in Real
Sea Conditions – Handles irregular and
multi-directional waves with no loss in precision. - Works Anywhere - Independent of GNSS &
RTK – Works outside of RTK coverage, in offshore
and deep-sea applications. Avoid RTK
base station or subscription cost and hassle. - High End MRUs at a fraction of the price –
Premium grade motion compensation also
for entry level Sonar systems. - Real-Time Heave, Roll, and Pitch Correction
– Delivers survey-grade data accuracy in all
conditions in real-time. - Ready-Calibrated and Maintenance-Free
– Reducing downtime and providing longterm
reliability for users. - Compact Form Factor – Can be mounted
on vessels, near sonar heads, or integrated
within sonar equipment. - Plug-and-Play Integration – Compatible with
leading sonar systems for seamless operation. - OEM Solutions Available – Can be integrated
directly into sonar systems for optimized
performance.
Motion Reference Units (MRUs) are essential for sensor systems for this application, providing high-accuracy measurements of the ROV's orientation and motion in all six degrees of freedom (6DoF): Roll, Pitch, Yaw, Heave, Surge, and Sway.
Norwegian Subsea offers the MRU Subsea, specifically designed for demanding underwater environments and ideally suited for ROV operations, including seabed mapping and subsea surveys. Housed in a robust, compact titanium casing, the MRU Subsea is depth-rated to 6000 meters and features a reliable Subconn connector for straightforward integration.
Our MRU Subsea utilizes advanced sensor fusion algorithms and state-of-the-art MEMS technology to deliver highly accurate and stable motion data, crucial for correcting multibeam echosounder or other survey sensor data. It is available in various accuracy levels (±0.05°, ±0.02°, ±0.01° Roll/Pitch) to meet diverse project requirements. An Inclinometer/VRU version is also available, offering the same high Roll/Pitch accuracy for applications where full 6DoF is not required.
Integration is simplified through standard Ethernet and serial communication ports supporting protocols like UDP, Modbus TCP, and Ethernet/IP. Like all Norwegian Subsea sensors, the MRU Subsea is designed for reliability and cost-effectiveness, typically requiring no recalibration during its operational life, reducing maintenance overhead for ROV operators.
Related products
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%
Further reading
Advanced motion compensation for sonars introduced at Ocean Business 2025
MRUs for vessel performance optimisation in focus at Europort 2025
Research Project to Test Value of MRU Data for Vessel Performance and Carbon Reduction
Related questions
- Read the full answer
Improving the accuracy of subsea sensors fundamentally relies on selecting a high-performance unit designed specifically for the demanding underwater environment. At Norwegian Subsea, we achieve superior accuracy through a combination of state-of-the-art MEMS sensor technology, advanced sensor fusion algorithms, and robust hardware engineering, validated in real sea conditions.
Our algorithms are crucial for filtering noise and accurately calculating motion parameters like Roll, Pitch, Heave, Surge, Sway, and Yaw (6DoF), even under complex, irregular motion patterns typical of subsea operations. Furthermore, our sensors undergo rigorous testing and validation in real sea conditions, ensuring their performance specifications are met in the environments where they will be deployed.
- Read the full answer
Selecting the appropriate motion sensor for a subsea Remotely Operated Vehicle (ROV) is critical for precise navigation, positioning, and tool manipulation. Key comparison factors include accuracy (Roll, Pitch, Heave, Yaw), depth rating, physical size and weight, robustness, ease of integration with ROV control systems, reliability in harsh environments, and overall cost-effectiveness.
Norwegian Subsea offers the MRU Subsea, specifically engineered for demanding underwater applications like ROV operations. This unit features a robust, compact titanium housing depth-rated to 6000 meters, making it ideal for deep-water tasks. We provide different accuracy levels to meet specific operational needs, with Roll and Pitch accuracy options of ±0.05° (Series 3000), ±0.02° (Series 6000), or ±0.01° (Series 9000), and a standard Heave accuracy of 5.0 cm or 5.0%. Our sensors utilize advanced MEMS technology and sensor fusion algorithms, validated in real sea conditions.
- Read the full answer
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.
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