Kongsberg MRU-E-JB3

Core Technical Specifications

• Sensing Core: 3-axis MEMS accelerometer + 3-axis MEMS gyroscope solid-state sensor
• Measurement Accuracy: Roll/Pitch ±0.05° full range
• Measurable Motion Parameters: Heave displacement, heave velocity, roll angle, pitch angle, three-axis linear acceleration
• Built-in Algorithm: PFreeHeave phase-free heave compensation algorithm
• Power Supply: 10–30 VDC wide range marine DC power
• Communication Interfaces: Ethernet TCP/IP, RS422 serial port
• Protection Rating: IP67 fully sealed stainless steel housing
• Overall Dimensions: 100 mm × 100 mm × 50 mm (sensor main unit); JB3 junction box matched split assembly
• Operating Temperature: -25 °C ~ +70 °C
• Shock Resistance: 10g peak vibration impact resistance, marine standard DNV certified

Function & Performance Features

1. Solid-state sensor without mechanical rotating parts, zero mechanical wear, long service life at sea
2. PFreeHeave algorithm eliminates phase delay of heave signal, accurate measurement under long ocean swell conditions
3. Support external ship speed and heading signal input to optimize motion calculation accuracy during vessel turning
4. JB3 junction box realizes multi-channel signal branching, one MRU-E unit can supply motion data to multiple on-board equipment simultaneously
5. Windows configuration software supports vector arm calibration, adjust measurement compensation point according to actual installation position
6. DNV marine equipment certification, meets offshore platform and ship safety equipment standards

Working Principle

1. MEMS gyroscope measures angular velocity of roll and pitch motion; accelerometer collects three-axis linear acceleration data
2. Built-in high-speed MCU integrates inertial data, uses PFreeHeave filtering algorithm to separate heave motion from vessel horizontal movement
3. External ship speed and heading signals are fused to correct motion calculation error caused by vessel turning acceleration
4. Real-time motion data is output via Ethernet/serial port to dynamic positioning system, multi-beam sonar and helideck monitoring host
5. JB3 junction box distributes single sensor signal to multiple receiving devices without signal attenuation

Material Composition & Structural Characteristics

• Sensor Main Unit Housing: 316L stainless steel integrated casting, salt spray corrosion resistant for marine environment
• JB3 Junction Box: Glass fiber reinforced plastic sealed shell, internal terminal block with anti-loose spring wiring terminals
• Internal Sensor Chip: Hermetically sealed MEMS inertial chip, humidity and moisture isolation protection
• Cable Interface: Waterproof marine grade cable gland, fluorine rubber sealing ring to prevent seawater fog infiltration

Installation Requirements

1. Install sensor main unit at vessel center of gravity or helideck geometric center as specified by system design
2. Fix unit with four M8 stainless steel bolts, mounting base must be horizontal to avoid initial measurement offset
3. JB3 junction box can be installed separately in electrical room, use shielded marine cable to connect sensor and junction box
4. All cable glands must be tightened with waterproof sealant filling to resist seawater mist corrosion
5. Reserve 100 mm maintenance space around unit for regular calibration and wiring inspection

Application Scenarios

• Offshore vessel dynamic positioning (DP) systems
• Ship helideck motion severity index (MSI) monitoring
• Multi-beam echo sounder seabed mapping attitude compensation
• ROV/AUV underwater robot attitude measurement
• Offshore wind turbine installation vessel heave compensation control
• Marine seismic survey ship motion correction

Usage Precautions

1. Execute vector arm recalibration after any vessel refit or sensor position change
2. Clean stainless steel housing salt spray deposits every month when operating in coastal high-salinity waters
3. Do not install near large marine thrusters to avoid vibration interference affecting measurement precision
4. Regularly check junction box terminal tightness every quarter to prevent signal open circuit caused by sea vibration
5. Avoid impact collision during ship maintenance; MEMS sensor internal chip is sensitive to strong impact