THE IDEAL MARINE MOTION SENSOR

This fifth generation MRU 5 is specially designed for high precision motion measurements in marineapplication and for users requiring high accuracy roll, pitch and heave measurements.

Typical applications

The MRU 5 is the ideal sensor for motion compensation of multi-beam echo sounders, offshore cranes,hydroacoustic positioning systems and dynamic motion monitoring of roll, pitch and linear accelerations on offshore structures. The MRU 5 provides documented roll and pitch accuracy of 0.02° RMS at a ±5° amplitude. The unit maintains its specified accuracy aboard any surface vessel or subsea vehicle.

Function

The MRU 5 incorporates three highly accurate accelerometers and three high-end Kongsberg Seatex developed MicroElectro-Mechanical-Structures (MEMS) gyros of type MRG (MRU Rate Gyro). The MRG gyro combines low noise, excellent bias stability and gain accuracy. Very high reliability is achieved by using solid state sensors with no rotational or mechanical wear-out parts.

The unit is delivered with Windows based configuration and data presentation software. In this software vector arms from where the MRU is mounted to center of gravity (CG) and two individually configurable monitoring points (MPs), can be defined. The heave measurements can be output in four different locations (the MRU itself, CG, MP1 and MP2) simultaneously on serial lines or Ethernet port. Typical monitoring point is the transducer head or the crane tip.

Output variables

The MRU 5 outputs roll, pitch and yaw angles and corresponding angular rate vectors. The unit outputs relative (dynamic) heave, surge and sway positions,

velocities and accelerations in adjustable frames.

PFreeHeave® Algorithm

The PFreeHeave algorithm uses past measurements to output a correct and phase-free heave from the MRU. PFreeHeave has an advantage in long swell conditions

and for applications that can utilize a heave signal that is delayed some minutes, typical seabed mapping applications.

External inputs

The MRU 5 accepts input of external speed and heading information on separate serial lines or Ethernet for improved accuracy in heave, roll and pitch during turns

and accelerations. For time synchronization the MRU accepts 1-second time pulse (1PPS) input on a TTL line (XIN) or as RS-232/422 signal.

Digital I/O protocols

For this fifth generation MRU data is available through both Ethernet interface and serial lines enabling easy distribution of MRU data to multiple users on board

the vessel. Output protocols for commonly used survey equipment are available on two individually configurable serial lines and Ethernet/UDP.

TECHNICAL SPECIFICATIONS