Gyro Compass And Inertial Navigation System (INS) MGC R2

The MGC R2 gyro compass includes three Ring Laser Gyros and three linear accelerometers.

TYPICAL APPLICATION

The MGC R2 product is a fully inertial navigation system (INS). It can output heading, roll, pitch, heave and position. Acceleration and velocity of linear motions, as well as angular rates, are output from the unit. The MGC R2 product outputs both processed and raw (gyro and accelerometer) sensor data.

The MGC R2 product can be used as a stand-alone unit or as an IMU in other systems. The product is designed for high precision maritime applications such as offshore operations and seabed mapping. The product includes integrated navigation algorithms with input from a GNSS receiver for output of aided position and heading data. The proven PFreeHeave® algorithms are part of the navigation algorithms that enable down to 2 cm accuracy in delayed heave output and 5 cm accuracy in real-time heave output. The linear position and velocity measurements can be output in up to four different points on the vessel.

The mounting bracket has been specially designed to enable easy alignment to the vessel axis or the axes of the system on which the unit shall measure the motion. This will ensure that the user gets precise measurements from the unit when it is installed.

FUNCTION

The MGC can operate in Gyrocompass mode and Integrated Navigation mode. In the Gyrocompass mode only, input of speed is required. In this mode the product will output heading, roll, pitch and heave accurately. In the Integrated Navigation mode, input of speed, position and PPS from a GNSS receiver is required (VTG, GGA, ZDA). In this mode the product will output heading, roll, pitch, heave and position.

The unit is delivered with Windows based configuration and data presentation software, the MRC+. In this software vector arms from where the MGC is mounted to the 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 MGC itself, CG, MP1 and MP2) simultaneously on serial lines or Ethernet ports. A typical measurement point is the echo sounder transducer head.

VARIABLES OUTPUT

The MGC outputs heading, roll and pitch and corresponding angular rate vectors. The unit outputs relative (dynamic) heave position, velocity and acceleration. In the Integrated Navigation mode it also outputs position in north and east direction in addition to height above the ellipsoid.

DIGITAL I/O PROTOCOLS

MGC data is available through both Ethernet interface and serial lines enabling easy distribution of 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.

FEATURES MGC R2

• 0.02° roll and pitch accuracy.
• 0.2° secant latitude heading accuracy.
• Includes INS capability.
• 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.
• Small size and low power consumption.
• Each MGC delivered with a Calibration Certificate.
• Selectable communication protocols in the Windows based configuration software.

TECHNICAL SPECIFICATIONS

ORIENTATION OUTPUT

• Angular orientation range : ±180°
• Resolution in all axes : 0.001°
• Accuracy roll, pitch : 0.02° RMS
• Accuracy heading : 0.2° RMS sec.lat
• Heading settling time (typical) : 17 min from start-up

GYRO OUTPUT

• Angular rate range : ±149°/s
• Angular rate noise : 0.020°/s RMS
• Bias stability (absolute bias) : 0.008°/h RMS
• Angle Random Walk : 0.035°/ ?h
• Scale factor error : 0.001 % RMS

ACCELERATION OUTPUT

• Acceleration range (all axes) : ±45 m/s2
• Bias stability (absolute bias) : 80 µg RMS
• Acceleration noise : 0.0003 m/s2 RMS
• Velocity Random Walk : 3.3 µg/?Hz
• Scale factor error : 0.008% RMS

HEAVE OUTPUT

• Output range : ±50 m, adjustable
• Periods (real-time) : 0 to 25 s
• Periods (delayed) : 0 to 50 s
• Heave accuracy (real-time) : 5 cm or 5% whichever is highest
• Heave accuracy (delayed) : 2 cm or 2% whichever is highest

POSITION OUTPUT

• Free inertial : 20 nm/h

ELECTRICAL

• Voltage input : 24 V DC nominal (18 to 32 V DC)
• Power consumption : Max 12 W (typical 11 W)

SERIAL PORTS

• Com1 : Bidirectional RS-422
• Com2 : Bidirectional RS-422 from junction box, user configurable RS-232, RS-422
• Com3 & Com4 : Input only, user configurable RS-232, RS-422
• Analog channels (junction box) : # 4, ±10 V, 14 bit resolution
• Ethernet output ports : 5
• Ethernet UPD/IP : 10/100 Mbps
• Digital output variables : 24 (max), Serial or Ethernet
• Data output rate (max) : 200 Hz
• Timing : < 1 ms

INPUT FORMATS

• NMEA 0183, incl. GGA, VBW, VTG, ZDA or MRU Normal format.

OUTPUT FORMATS

• MRU normal : Sounder
• NMEA 0183 proprietary : EM3000
• Atlas Fansweep : TSS1
• Seapath binary 23, 25, 26 : PFreeHeave®
• KM binary : MDL Trim Cube
• RDI ADCP : Tokimec PTVG
• NMEA GGA, GLL, HDT, THS, ROT, VTG, GST, VER, HCR

OTHER DATA

• MTBF (computed) : 50 000 h
• MTBF (service history based) : 100 000 h
• Material : Anodised aluminium
• Connector (MIL. spec.) : Souriau 851-36RG 16-26S50

WEIGHTS AND DIMENSIONS

• Weight : 8.1 kg
• Dimensions (HxLxW) : 188.9 x 189.5 x 189.5 mm

ENVIRONMENTAL SPECIFICATIONS

• Operational temperature range : -15 °C to +55 °C
• Storage temperature range : -25 °C to +70 °C
• Enclosure protection : IP66
• Vibration : IEC 60945/EN 60945

ELECTROMAGNETIC COMPATIBILITY

• Compliance to EMCD, immunity / emission : IEC 60945/EN 60945

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