Motion Reference Units (MRU)


Marine Floor Mapping The Motion Reference Unit (MRU) product line was first released in 2004 when Inertial Labs MEMS-based sensor solutions began to compete in performance with traditional FOG units. Easy integration of the MRU product line for the end-user means competitive performance at no extra cost.

Factory configured to output parsed data using Inertial Labs message formats or Kongsberg/Seatex and Teledyne TSS* data formats give the user the ability to easily replace dated MRU’s with the Inertial Labs product line.

Inertial Labs developed the MRU to meet requirements for all marine and hydro-graphic applications. The MRU is a high-performance strap-down Motion Sensor that determines Pitch & Roll, Heave, Surge, Sway, Linear Accelerations, Angular Rates, Heading, Velocity, and Position for any device on which it is mounted to.

The Inertial Labs team of skilled engineers provides expertise to help users select and configure from the models available: MRU-B1, MRU-B1.1, MRU-B2, MRU-E, MRU-P and MRU-PD (with subsea models available). Our support team helps set up units for all application bases to satisfy both GNSS enabled, and GNSS-denied environments.



MRU Models Available



Subsea Enclosed Options



MRU Use Cases


The Inertial Labs Motion Reference Unit has been commonly used for the following applications. Visit the Marine Use Cases page to see more details on specific Marine projects that Inertial Labs has been involved in.

marine vessel compass

Marine Vessel Navigation

Easily paired with on-board Autopilot systems and controllers, the MRU product line features two models that are widely used for Navigation systems aboard vessels. The Professional version of the MRU (MRU-P) features a single antenna GNSS receiver used for position and velocity calculations. Similarly, the Professional, Dual Antenna MRU-PD is able to calculate precise position and velocity as well as heading with accuracy of 0.05 degrees (RMS), making the ideal solution for navigation on any sized marine platform.

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boat in ocean

Hydrographic and Bathymetric Surveying

Bathymetric or Hydrographic surveys are survey methods used for submarine topography that have been implemented for observation of marine landscapes and structures for several decades. The Inertial Labs MRU has the ability to be used with single beam and multibeam echo-sounders (SBES or MBES) as well as other external sensors using industry-wide accepted sentence formats (NMEA and TSS-1), where it directly passes information to internal algorithms while operating. The makes the MRU the ideal solution especially when being used for Hydrographic and Bathymetric surveying applications.

Cargo Transfer

Cargo Transfer and Loading Stabilization (ROV)

Effectively communicating motion and navigation parameters (position, velocity, heave, surge and sway) for proper heave compensation while loading and unloading cargo and maritime equipment is an essential application used in most all shipping industries. Whether the system is fully automated, or dependent on user response, having a device that can be easily installed to replace a dated unit is where where Inertial Labs stands out in comparison with competitors. Inertial Labs builds modular and custom solutions using commonly used interfaces and data formats.

yellow marine vessel

Research Vessels and Buoys

Research vessels and buoys may need to run for weeks at a time without interruption of data-streams. Inertial Labs builds robust, IP67 or subsea enclosed solutions with internal data-logging abilities to record data for post-processing or real time monitoring. Default solutions can be set up to stream data wirelessly to nearby base stations where research teams can use data to interpret ocean conditions.

Oil rig

Helideck and Offshore Drilling Monitoring

The Motion Reference Unit is commonly used for modular captive marine vessels (MCV) and helideck monitoring (HMS); stabilizing platforms and communicating with multiple other response systems to know how to compensate for heave, surge and sway of a vessel. Offshore oil drilling or ocean-based wind farms industries are other common markets where Inertial Labs is able to provide the sensor solutions required to account for motion in the ocean.

map target

Autonomous Vessels (AUV and USV)

Autonomy has become the fastest growing industry of this century. Autonomous Underwater Vessels (AUV) or Unmanned Surface Vehicles (USV) can be used in military applications for minesweeping in the ocean, or commercial applications for underwater scanning and surveying. Inspection processes have now taken on the autonomous approach as well as the climate and environmental markets especially when navigation solutions like ones supplied by Inertial Labs are becoming increasingly more cost-effective.

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Integrations with the Motion Reference Unit


Mapping Software

The Inertial Labs Motion Reference Unit has been designed to be compatible with a number of different solutions. For hydrographic or bathymetric surveying, integration is support for Single Beam and Multi-Beam Echo-Sounders (SBES or MBES).

Additionally, take advantage of sensors that are already available on your platform and integrate with the MRU product line to increase performance and navigational accuracy. Supported external sensors include: Airspeed, Wind-speed, External Gyro-compass, Velocity Sources (Doppler Velocity Logs) and External GNSS Receivers (Single or Dual Antenna).


Supporting Software


Waypoint Software         LabVIEW        QINSY Logo    Hypack software

Inertial Labs supplies drivers and necessary tools for easy integration with commonly used platforms such as Waypoint, LabVIEW, QiNSY and Hypack products*.


Performance Plots


Heave Accuracy (10Hz and 20Hz Waves)

Heave Error 10 secHeave Error 20 sec

Dynamic Pitch and Roll Accuracy (20Hz Waves)

Pitch error 20 secRoll error 20 sec

Heave, Pitch & Roll Dynamic Testing


Certificate of Design Assessment


ABS Design CertifiedRepresentatives of the American Bureau of Shipping assessed design plans and data of all Inertial Labs MRU products. This assessment is a representation by the Bureau as to the degree of compliance the design exhibits with applicable sections of their Rules. This PDA is intended for a product to be installed on an ABS classed vessel, MODU or facility which is in existence or under contract for construction.

Certificate number 19-HS1851412-PDA

Date 10 May 2019


MRU Development Kits


OEM Dev Kit
IP67 Dev Kit


Established in 2001, Inertial Labs is a leader in position and orientation technologies for commercial, industrial, aerospace and defense applications. Inertial Labs has a worldwide distributor and representative network covering 20+ countries across 6 continents delivering compact, high performance and affordable Miniature Orientation Sensors, Motion Reference Units (MRU), Attitude & Heading Reference Systems (AHRS) and GPS-Aided Inertial Navigation Systems (INS). With application breadth on Land, Air, and Sea; Inertial Labs covers the gambit of inertial technologies and solutions. Contact us to learn more.