What sensor technologies are used in ROVs?
Remotely Operated Vehicles (ROVs) rely on a suite of sophisticated sensors to navigate complex subsea environments, perform intricate tasks, and gather data. Key sensor technologies typically include imaging sonar for obstacle avoidance and mapping, cameras for visual inspection, Doppler Velocity Logs (DVLs) for measuring speed over the seabed, depth sensors, altimeters, and crucially, high-performance motion sensors.
Motion Reference Units (MRUs) are fundamental components within an ROV's sensor package. They provide precise measurements of the vehicle's orientation and motion across all six degrees of freedom (6DoF): Roll, Pitch, Heave, Yaw, Surge, and Sway. This high-fidelity motion data is essential for vehicle stability, accurate navigation when integrated with systems like DVLs or acoustic positioning (USBL/LBL), and precise control of manipulators and tooling.
Norwegian Subsea specializes in developing advanced MRUs utilizing state-of-the-art MEMS sensor technology and robust sensor fusion algorithms, delivering the high accuracy and reliability required for demanding ROV operations. Our MRU Subsea is specifically designed for these applications, featuring a compact, 6000-meter depth-rated titanium housing, a standard Subconn connector for easy integration, and flexible Ethernet and serial communication options supporting various industry protocols. For applications primarily requiring orientation data, cost-effective Inclinometer/VRU versions are also available, offering the same high Roll and Pitch accuracy.
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
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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.
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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.
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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.
Related applications
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.
Riser Monitoring
The NORSUB Subsea MRU is specifically designed to provide highly accurate measurements of roll, pitch (inclination), and lateral motions in risers.
Subsea Surveys
Subsea surveys often demand precise tilt measurements (roll and pitch) for various purposes, such as installation tasks or continuous monitoring of tilt changes and deflections in subsea structures.
ROV/AUV
Reliable motion sensors are vital components in the navigation system and motion compensation of payload sensors for ROVs and AUVs.
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