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Motion Reference Unit - MRU

Operating vessels at sea is, by its very nature, a highly challenging activity. In order to undertake tasks such as wave height monitoring, using cranes during rough weather, or determining where vessels are using dynamic positioning, roll, pitch, yaw and heave motion needs to be measured. This is where Motion Reference Units (MRUs) come in and KONGSBERG has been a leader in this field for over 25 years.

The MRU is suitable for any maritime operation that requires attitude determination and motion compensation. Kongsberg's range of motion sensors provides high accuracy motion measurements in all dynamic environments. They cover all marine activities, from small hydrographic vessels to large vessels and installations.

Typical applications

  • Motion compensation of single and multi-beam echo sounders
  • Orientation and attitude measurements on AUVs and ROVs
  • High speed craft motion control and damping systems
  • Heave compensation of offshore cranes
  • Dynamic positioning
  • Hydro acoustic positioning
  • Ship motion monitoring
  • Ocean wave measurements
  • Antenna motion compensation and stabilization

More about MRU applications

High reliability

Built with solid-state gyros and accelerometers, Kongsberg's MRUs provide realtime motion measurements with high dynamic accuracy. In-house, state-of-the-art design, construction and assembly provide an MRU with extremely high reliability in the most demanding marine environments.

Merging the art of technology with applications

Micro Electro Mechanical System (MEMS) -based gyros have been implemented in many different variations over the past 25 years and a constant focus on innovation and ingenuity has led to continous improvements in price/performance. Consequently, MEMS-based gyros today challenge the 'prone to wear' mechanical gyro solutions, as well as gyros based on fibre optic (FOG) technology. A gyro developed by KONGSBERG, optimized for use in the high-end of the Kongsberg Motion Reference Unit (MRU) product range, is a defining example of the MEMS-based gyro design, demonstrating new performance levels for this technology.


The MRUs can be supplied with a variety of accessories such as MRU mounting brackets, junction boxes, cables and subsea housings. Depth rated from 10 to 4,000 metres.

  • MRU with bracket

  • MRU accessories

  • The MRU family

State-of-the-art production facilities

To ensure the required quality and meet the demands from our customers, the production process is continuously improving. Service, calibration and verification of MRU units in order to meet required specifications are a vital part of the process.

Our production process meets all relevant standards and is certified in accordance to ISO 9001 and ISO 14001.

MRU product range

Model Roll/pitch Acceleration Heave PFree Heave* Period PFree Period*
MRU 5+ 0.008° 0.001 m/s2 5 cm 2 cm 25 s 50 s
MRU 5 0.02° 0.01 m/s2 5 cm 2 cm 25 s 50 s
MRU E 0.05° 0.01 m/s2 5 cm 3 cm 25 s 50 s
MRU H 0.05° 0.01 m/s2 5 cm 3 cm 25 s 50 s
MRU 3 0.08° 0.02 m/s2 5 cm 4 cm 18 s 50 s
MRU S 0.3° 0.05 m/s2 15 cm 5 cm 18 s 50 s
MRU 2 0.10° 0.01 m/s2      
MRU D 0.35° 0.04 m/s2        

An embedded version of the MRU is available, read more here.
*PFreeHeave® is a delayed heave output where phase errors are removed. The delay is 132 sec.

Servicios y soporte

  • 24/7 Technical support

    Our 24/7 technical support team is there to help at any time, day or night, wherever your vessel is.

  • Conversions, retrofit and refit

    We understand the importance of having the right parts, available in the right place, at the right time.

  • Training

    Ensure that your crew is properly and thoroughly trained. This will reduce operational risk, downtime and maximise return on asset investment.