Description
Key Technical Specifications
| Parameter | Specification |
|---|---|
| Sensor configuration | 3 accelerometers + 3 MEMS rate gyros |
| Roll and pitch accuracy | 0.02° RMS |
| Real-time heave accuracy | 5 cm |
| Real-time heave period | 25 seconds |
| Heave acceleration accuracy | 0.01 m/s² |
| Motion outputs | Roll, pitch, yaw, angular rates, heave, surge, sway and acceleration |
| Data output rate | Up to 200 Hz, depending on configuration |
| Communication | Ethernet and serial communication |
| Mounting | Fixed installation with orientation configuration |
| Configuration software | Windows-based MRU configuration software |
The accuracy figures above correspond to the standard MRU-5 model, not the higher-performance MRU-5+ variant. Interface availability and output configuration must be checked against the actual hardware and junction-box arrangement.
Product Introduction
Kongsberg Seatex MRU-5 Marine Motion Reference Unit
The Kongsberg Seatex MRU-5 is an inertial motion sensor designed for marine applications requiring accurate vessel attitude and linear motion measurements. Its solid-state accelerometers and MEMS rate gyros measure vessel movement and provide data for motion compensation, navigation, and marine equipment stabilization.
The unit can supply roll, pitch, yaw, angular-rate, and heave information to compatible systems. Typical applications include multibeam sonar compensation, offshore crane monitoring, hydrographic surveying, and dynamic positioning support.
MRU-5
Major Features and Advantages
Six-axis inertial sensing
Three accelerometers and three rate gyros provide the measurement foundation for attitude and dynamic motion calculations. The solid-state sensor arrangement avoids the mechanical wear associated with rotating gyro assemblies.
High-accuracy attitude measurement
The standard MRU-5 provides 0.02° RMS roll and pitch accuracy under specified test conditions. This supports applications where vessel movement must be compensated in measurement and positioning systems.
Heave measurement
The unit provides real-time heave data, with a documented accuracy of 5 cm at a 25-second measurement period. Delayed heave processing may provide different accuracy characteristics.
Flexible installation configuration
The MRU software supports configuration of mounting orientation and lever-arm corrections between the sensor location and selected monitoring points. Correct installation geometry is essential for accurate motion compensation.
Multiple output variables
The MRU-5 can provide attitude angles, angular rates, accelerations, and linear motion measurements to compatible marine systems. Available output formats depend on the selected interface and configuration.
Application Scenarios and Field Considerations
- Dynamic positioning systems: Supplies vessel attitude and motion information to compatible DP equipment.
- Hydrographic surveying: Compensates multibeam sonar and other survey instruments for vessel roll, pitch, and heave.
- Offshore crane operations: Provides motion information for crane-tip and load-motion compensation systems.
- ROV and subsea operations: Supports motion measurement and compensation for compatible subsea positioning and survey equipment.
Engineering and replacement precautions
- versus +: The + has different performance specifications. Do not transfer its accuracy figures to the standard .
- Mounting alignment: Incorrect orientation or lever-arm settings can introduce systematic errors into motion measurements.
- Junction-box compatibility: Fifth-generation MRUs use the JB3 junction box as the standard arrangement. Compatibility with older JB1 installations has interface limitations.
- Subsea housing: The fifth-generation unit has different physical dimensions from earlier generations. An older subsea bottle may not accommodate the newer unit.
- Interface changes: Connector similarity does not guarantee electrical or signal compatibility. Verify serial and Ethernet pin assignments and output-variable definitions before replacing an older MRU.
Related Kongsberg MRU Models and Accessories
| Model | Description |
|---|---|
| + | Higher-performance motion reference unit |
| MRU-E | Marine motion reference unit for different performance requirements |
| MRU-H | Motion reference unit variant |
| MRU-3 | Lower-performance motion reference unit |
| MRU-D | Roll and pitch motion reference unit |
| MRU-M-JB3 | Fifth-generation MRU junction box |
| MRU-M-MB3 | MRU mounting bracket |
| MRU-M-SB series | Subsea housing options |
These models and accessories serve different performance or installation requirements. Confirm the complete part number before ordering.
Procurement and Replacement Checklist
Before purchasing or replacing a Kongsberg , verify:
- Complete model designation and serial number.
- Fifth-generation hardware identification.
- versus + performance variant.
- Junction-box model and communication interface.
- Mounting bracket and installation orientation.
- Subsea housing dimensions, if applicable.
- Output configuration and software compatibility.
- Calibration and functional test documentation.
Replacement recommendation: Do not select an MRU solely by matching the model name. Confirm its serial-number generation, junction box, interface requirements, mounting geometry, and configured output variables.
