Moog Crossbow GNAV540 - Manual (Page 23)

GNAV540 User Manual
7430‐0808‐01 Rev. B Page 23
Figure 2 GNAV540 Software Block Diagram
.
X / Y / Z Body
Accelerometers
6 - DOF Sensor Cluster
Sensor
Calibration
Axes Rotation
GPS Data
Internal/External
Kalman Filter and Dynamic State Model
Integration to 100 Hz
Velocity, GPS
Position Output
Hard/Soft Iron
Calibration
UseMags
X / Y / Z
Magnetometers
NAV/AHRS only
IMU - Scaled Packets
(S0,S1,S2)
All Units
NAV/AHRS/VG/IMU
Gravity Reference
Turn Rate
(Internal
Computation)
Free Integrate
TurnSwitch
Threshold
UseGPS
Stationary Yaw
Lock
X / Y / Z Body
Rates
100Hz
Signal
Proc.
Chain
Extended Kalman Filter (EKF)
Drift Correction Module
VG/AHRS – Angle
Packets
(A0,A1,A2)
NAV/AHRS/VG
NAV - Nav Packets
NAV/AHRS/VG
Integration to
Attitude
Unit Settings & Profile*
Communication Settings
Axes Orientation
Low Pass Filtering
Free Integrate
UseGPS
UseMags
TurnSwitchThreshold
DynamicMotion
Restart On Overange
Dynamic Motion
Programmable BIT Alerts
Aiding Sensors
Built In Test
& Status
Data
Available to
User
Measurement
Data Available to
User (Fixed Rate
or Polled)
Status Packet (T0)
(N0,N1,N2, N3)
The GNAV540 features include sensors used in the EKF for the drift correction of the 6‐DOF inertial sensor cluster
A 3‐axis magnetometer and a GPS receiver are used for correcting the drift on yaw/heading angle, increasing the
accuracy of the attitude estimation by incorporating these sensor signals into the EKF and providing a navigation
solution. The common aiding sensor for the drift correction for the attitude (i.e., roll and pitch only) is a 3‐axis
accelerometer.
Figure 3 below illustrates the unit setting and profile block, which configures the algorithm to user and application
specific needs. This feature is one of the more powerful features in the GNAV540 architecture, as it allows the
GNAV540 to work in a wide range of commercial applications by setting different modes of operation.