Moog Crossbow NAV440 Series - Manual (Page 18)

Page 18
NAV440 User Manual
7430‐0131‐01 Rev. F
• Coupled to the 6‐DOF MEMS inertial sensor cluster is a high performance Digital Signal Processor (DSP) that
utilizes the inertial sensor measurements to accurately compute navigation information including attitude,
40 Series heading, and linear velocity thru dynamic maneuvers (actual measurements are a function of the 4
unit as shown in Table 2).
The DSP processor makes use of internal and external magnetic sensor and/or GPS data to aid the
performance of the inertial algorithms and help correct long term drift and estimate errors from the inertial
sensors and computations. The navigation algorithm utilizes a multi‐state configurable Extended Kalman
Filter (EKF) to correct for drift errors and estimate sensor bias values. This algorithm runs on a 150MHz
32‐bit DSP that has approximately four times the computational power of Moog Crossbow ’s earlier
generation Inertial Systems.
• Another unique feature of the 440 Series is the extensive field configurability of the units. This field
configurability allows the 440 Series of Inertial Systems to satisfy a wide range of applications and
performance requirements with a single mass produced hardware platform. The basic configurability
includes parameters such as baud rate, packet type, and update rate, and the advanced configurability
g the includes the defining of custom axes and how the sensor feedback is utilized in the Kalman filter durin
navigation process.
The 440 Series is packaged in a fully sealed lightweight housing which provides EMI, vibration, and moisture
resistance to levels consistent with most land, marine, and airborne environments. The 440 Series utilizes an RS‐
232 serial link for data communication, and each data transmission includes a BIT (Built‐In‐Test) message providing
system health status. The 440 Series is supported by Moog Crossbow ’s NAV‐VIEW 2.X, a powerful PC‐based
operating tool that provides complete field configuration, diagnostics, charting of sensor performance, and data
ogging with playback. l
Summary of Major Changes from the 300/400 Series and the 420 Series
Mechanical Size and Footprint
The mechanical footprint of Moog Crossbow ’s new 440 Series Inertial Systems is compatible with prior generation
Inertial Systems including Moog Crossbow ’s 400 Series (IMU400, VG400, AHRS400) and the NAV420 Series
products. The mounting plate foot print is the same and the connector location is identical. The 440 Series units
are shorter than their equivalent 400 Series product (i.e. the AHRS440 is shorter than the AHRS400, etc). The 440
Series unit is dimensionally equivalent to the NAV420. For detailed mechanical and installation drawings, refer to
. Appendix E. Mechanical Specifications
Connector Pin Out & Operating Voltage, Current
The DB‐15 male connector on Moog Crossbow ’s 440 Series Inertial Systems has a backward compatible pin out
with the 400 Series and 420 Series. However, the 440 Series has a secondary optional‐use communications port for
internal or external GPS.
Operating Performance and Accuracy
The 440 Series has been characterized in a wide range of land and airborne applications. In the qualification
testing, the dynamic accuracy of the 440 Series has shown superior performance when compared to the equivalent
model of 400 and 420 Series, reducing attitude estimation errors in half during certain critical dynamic maneuvers
without the use of GPS aiding. With GPS aiding in the NAV440, attitude estimation is improved by an order of
magnitude compared with 400 series products. Recommended configuration settings are discussed in
. The 440 Series functions are discussed in
Appendix B.
Application Examples Chapter 2. 440 Series Functions.