Motion Reference Unit

The MRU 5 represents the pinnacle of marine motion sensing technology - embodying a specially designed fifth-generation device that excels in delivering high precision motion measurements within marine applications. It stands out in its ability to offer highly accurate roll, pitch, and heave measurements for the most demanding users.

High Precision Applications

Primed for excellence, the MRU 5 is the optimal sensor for various motion compensatory functions used in multi-beam echo sounders, offshore cranes, hydroacoustic positioning systems, and dynamic motion monitoring on offshore structures. Its unparalleled roll and pitch accuracy of 0.02° RMS within a ±5° amplitude is proven and documented, ensuring reliable performance on any surface vessel or subsea vehicle.

Advanced Sensor Technology and Configurability

Integrating three top-tier accelerometers with three premier Kongsberg Seatex developed MEMS gyros of MRG type, the MRU 5 exhibits low noise characteristics alongside exceptional bias stability and gain accuracy. This high reliability is attributed to the use of solid-state sensors, which circumvents any mechanical wear. Adding to its feature set, this unit comes with specialized Windows-based configuration and data presentation software, which allows for the precise definition of vector arms to the center of gravity and two individually configurable monitoring points.

Enhanced Data Output and Complementary Algorithms

The MRU 5 is proficient in the output of critical motion-related variables, such as roll, pitch, and yaw angles as well as angular rate vectors across various adjustable frames. Furthermore, with the employment of the cutting-edge PFreeHeave algorithm, it overcomes the perils of long swell conditions and is ideal for applications that can utilize a delayed heave signal, commonly observed in seabed mapping operations. External speed and heading inputs are also accepted to augment the accuracy of heave, roll, and pitch under dynamic conditions.

Key features

  • 0.02° roll and pitch accuracy
  • Outputs on RS-232, RS-422 and Ethernet
  • High output data rate (200 Hz)
  • Precise heave at long wave periods by use of PFreeHeave algorithms
  • Lever arm compensation to two individually configurable monitoring points
  • Meets IHO special order requirements
  • Small size, light weight and low power consumption
  • No limitation to mounting orientation
  • Each MRU delivered with Calibration Certificate
  • Selectable communication protocols in the Windows based MRU configuration software
  • 2-year warranty

Technical specifications


Roll/pitch Static RMS:
Roll/pitch Dynamic 1-sigma:
Heave Real-time RMS:
5 cm/5 %
Heave Period Real-time:
25 s
Heave Delayed RMS:
1 cm/1 %
Heave Period Delayed:
50 s

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