Rescue Mission: GPS Applications in an Airborne Maritime Surveillance System
Airborne search and rescue missions at sea pose a set of challenging technical and operational requirements to meet the life-critical application involved. These require specialized navigation and flight management capabilities that, in turn, support a variety of other surveillance sensors and functions. A team of German engineers describe a system developed by their company to meet these requirements.
Maritime search and rescue (SAR) operations do not fit the usual and customary operational modes for aircraft operations. Consequently, neither do their navigation and flight management system (FMS) requirements.
SAR missisions are not based on schedules but rather on ad hoc events and flights. Once the mission control center receives word of an accident (ship disaster, aircraft crash, etc.), an aircraft receives a mission order and begins a high-speed ferry flight to the area of concern. After arrival in the area of the incident, the aircraft typically performs a low-altitude (500 to 1,500 feet), low-speed search flight to locate survivors and the vessel.
In executing this search, the crew employs a suite of surveillance radars, electro-optical sensor, and scanning and direction finding equipment to localize transmissions of emergency beacons that may have been activated during the accident. Once the target (person, ship, aircraft) is found, the crew drops needed equipment, such as life rafts or pumps, out of the aircraft.
The target position and other details are reported to the mission control center in order to initiate further rescue activities. All of these activities require precise navigation and sensor control, which may be obtained by a number of GNSS/GPS applications on board the aircraft.
This article describes an airborne surveillance system, AeroMission, developed by Aerodata AG, and the GPS/inertial navigation system (INS) that supports its operation.
In addition to SAR missions, AeroMission is also suitable for maritime surveillance, border and anti-smuggling patrols, pollution detection and mapping, fishery control, offshore oil field monitoring, and research applications.
In supporting AeroMission, an integrated GPS/IMU navigation system — AeroNav — combines the GPS advantages of long-term stability and absolute accuracy with those of inertial navigation — short-term accuracy during phases of high dynamics in which GPS positioning may be lost or degraded.
A separate GPS/INS system also provides attitude reference by using strapdown algorithms providing position and velocity solutions. Turn rates and accelerations given by the IMU are corrected by the GPS pseudorange measurements. These corrections are calculated by a Kalman filter.
The basic system components include:
Other sensors such as side-looking airborne radar or microwave radiometer can be integrated as options into the suite.
. . .
. . .
. . .
Flight Deck Interface
. . .
System Qualification and Certification
. . .
For the complete story, including figures, graphs, and images, please download the PDF of the article, above.
ManufacturersAeroNav, the integrated GPS/IMU unit from Aerodata AG, Braunschweig, Germany, incorporates a GPS receiver from NovAtel, Inc., Calgary, Alberta, Canada, and an inertial navigation system from Sagem Défense Sécurité, Paris, France. AeroMission also includes a separate GNSSU, the Primus 2000, from Honeywell, Inc., Phoenix, Arizona.
Copyright © 2017 Gibbons Media & Research LLC, all rights reserved.