GPS-INS Integration
|
|
|
|
|
|
|
Written by Bradley S. Melara
|
|
Monday, 09 March 2009 |
|
Honeywell integrates a ring laser gyro-based INS with a five-channel GPS P/Y code receiver into its product called H-764G, which utilizes line-of-sight information in a central Kalman filter, Moya says. "Embedded GPS/INS is the technology that's in the greatest demand."
The device appeals to the military because it eliminates a separate box in aircraft and other platforms that require GPS and INS capability, Moya explains. Moreover, the integrated system provides greater capability than the sum of its parts would suggest and does so in a package that remains unclassified when keyed.
GPS and IMU systems are superior navigational devices in their own rights, but each has a severe weakness. The validity of a GPS signal degrades or disappears as its receiver loses contact with the Navstar satellites because of electronic jamming or terrain masking. The validity of IMUs, on the other hand, degrades over time. But integrating the two enables the GPS to update the IMU and keep it accurate while the GPS receiver has line-of-sight access to all the Navstar satellites. When line-of-sight satellite contact is lost, the IMU most often is accurate enough to provide reasonably valid navigational information until the GPS signals can be restored.
Since many existing military opportunities involve upgrades and retrofits, many designers are taking the opportunity to replace standalone GPS receivers and INSs with combined GPS/INS systems, which can be critical in areas where terrain blocks GPS signals -- even for infantry soldiers taking cover behind rocks and other obstructions.
Future products from Rockwell Collins will include 12-channel, all-in-view capability," says Tyler Trickey, the company's marketing manager for navigation products. "They'll be able to track all the satellites visible simultaneously, whereas the traditional military receivers track four or five satellites at a time."
In the past, 5-channel receivers have been the baseline for high-performance airplanes like the F-16 jet fighter, which need to track four satellites at once to get 3-D position and time solutions, with the fifth channel looking at other satellites and performing housekeeping functions, Trickey explains.
|
|
Last Updated ( Monday, 09 March 2009 )
|
Vehicle GPS Unit