MRU-D KONGSBERG Motion Reference Unit (MRU)

The MRU-D is Kongsberg Marine's fifth-generation dedicated roll/pitch motion reference unit, primarily designed for ship attitude measurement and dynamic compensation. It serves as a core inertial sensor for systems such as DP, sonar, and antenna stabilization.

I. Core Positioning and Design Features

Dedicated 2-axis attitude sensor: Outputs only Roll/Pitch, no Yaw/Heave; employs a 2-axis MEMS gyroscope + accelerometer, with no moving mechanical parts, maintenance-free.

Horizontal acceleration suppression: The algorithm can cancel horizontal acceleration interference, maintaining accuracy even when installed off-center from the ship's center of gravity, superior to ordinary inclinometers.

Installation constraints: Must be installed vertically (interface end facing upwards), suitable for scenarios with limited Roll/Pitch range.

Compact and lightweight: 7cm shorter than earlier MRUs, suitable for space-constrained shipboard/equipment integration.

II. Key Technical Parameters

Measurement accuracy: Roll/Pitch 0.35° RMS (static). Dynamic Performance: Output refresh rate up to 200 Hz, low latency, high dynamic response.

Power Supply: 18–32 VDC (Marine 24 VDC standard), low power consumption design.

Communication Interfaces:

Serial Port: RS-232 / RS-422, supports NMEA 0183 and other protocols.

Ethernet: TCP/IP, multi-user data distribution.

Protection and Environment: IP67, wide temperature range -20°C to +60°C, vibration/salt spray resistant, conforms to classification society specifications.

Certifications: Comes with a calibration certificate, meets relevant maritime and IHO standards.

III. Typical Application Scenarios

Dynamic Positioning (DP) System: Provides attitude reference for K-Pos DP.

Sonar / ADCP: Attitude compensation for fish finder sonar and ADCP current measurement.

Antenna Stabilization: Motion compensation for satellite communication/radar antennas.

Navigation Log: Attitude data acquisition for VDR/SVDR.

Ship Automation: Attitude linkage control of propulsion, ballast, and cranes.

IV. Differences from Other MRU Models

MRU-D: 2 axes (Roll/Pitch), accuracy 0.35°, vertical installation, low-cost dedicated type.

MRU 5/5+: 3 axes (Roll/Pitch/Yaw) + Heave, accuracy 0.008°~0.02°, all-attitude, high-precision general-purpose type.

MRU Z: 3 axes + Heave, accuracy 0.15°, focuses on heave compensation, suitable for surveying/cranes.

V. System Integration Key Points

Includes MRC + configuration software (Windows) for parameter setting, calibration, and data monitoring.

Supports lever arm compensation, adapting to error correction for different installation positions.

Can be directly connected to Kongsberg control systems such as RCU500, K-Chief, and K-Pos, and can also interface with third-party equipment.