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 for MRUs
- 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
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.
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 2||0.10°||0.01 m/s2|
|MRU D||0.35°||0.04 m/s2|
*PFreeHeave® is a delayed heave output where phase errors are removed. The delay is 132 sec.