New Motion Reference Unit

The new Motion Reference Unit MRU 5+ from Kongsberg Seatex builds on the already cutting-edge technology employed in previous MRU generations, of which 7000 units have been installed since the product line was launched in 1992. MRU 5+ takes roll, pitch and heave measurements closer to perfection than ever before, with documented roll and pitch accuracy of 0.01° RMS.

The high accuracy provided by the MRU5+ is achieved through use of sophisticated inertial sensors including linear accelerometers and Micro-Electro-Mechanical-Systems (MEMS) rate gyros specially developed for maritime use by Kongsberg Seatex. The new MEMS rate gyro (three in each MRU) combines very low noise, excellent bias stability and outstanding gain accuracy. Solid-state sensors with no moving parts, enable high lifetime reliability across all applications, which include:

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

The installation and configuration of the MRU 5+ is straightforward. A Windows-based configuration and data presentation software is flexible and includes data protocols for the most commonly used single and multibeam echo sounder systems. A series of simple menu prompts allows the user to choose the optimum configuration for a specific application ensuring that MRU 5+ will always provide maximum performance.

In addition to simple, flexible installation and configuration, MRU 5+ makes it easy to distribute the MRU data to multiple users onboard the vessel via Ethernet, whilst output protocols for commonly used survey equipment are available on two individually configurable serial lines and Ethernet/UDP. Further connections include external input of speed and heading information on separate serial lines for improved accuracy in heave, roll and pitch during measurements turns and acceleration.