The Global Hawk unmanned aerial vehicle (UAV), like many military systems, has evolved toward a more open design through the use of common interfaces, data formats, and protocols.
The earliest variant, Block 10, integrated all flight and mission functions in one processor with proprietary software, in order to minimize size, weight, and power (SWAP) and maximize payload and fuel capacity, says Bill Walker, director of business and strategy development for Northrop Grumman's Future Unmanned Systems, Strike and Surveillance Systems Division. The mission computers use 6U VME boards made by Curtiss-Wright Controls Embedded Computing in Ashburn, Va.
The next iteration moved away from such tight integration, separating flight control, and mission processing functions into different hardware packages as a basis for a series of RQ-4B aircraft, Blocks 20, 30, and 40. This allows the sensor management unit developed by Curtiss-Wright to change without affecting the flight avionics. Block 20 added Gigabit Ethernet within the sensor management unit. Block 30 and 40 aircraft also added removable bulkheads to more easily accommodate different payloads.
Northrop Grumman is also decentralizing the mission management piece, further opening the architecture. The program is moving toward a service-oriented architecture (SOA), which the U.S. Air Force says enables modularity within a family of systems. SOA separates functions into distinct units, or services, which a system makes accessible over a network in order to allow applications to combine and reuse them in performing new functions. These services and their corresponding applications communicate with each other by passing data in an XML protocol with well-defined, shared formats.
Northrop Grumman's goal is "to make the architecture more open in order to adopt COTS components and software applications more readily," Walker says. The evolution has also involved breaking up and modularizing software, with cleaner interfaces, for easier upgrades.
As the UAV continues to evolve -- customers now include, or will soon include, not only the U.S. Air Force, but the U.S. Navy, German military, and NATO -- the architecture will continue to open, Walker predicts. The Air Force has already contracted with the company to re-architect the ground and aircraft communications and ground station designs for greater interoperability.