Large UAVs Ramp Up Sensor Processing Capabilities

February 06, 2009

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By integrating more powerful computer engines, along with speedy fabric interconnects, large UAV platforms are cranking up their sensor processing muscles to a new leBy vel.

By Val Zarov

The military's rapid move toward IPbased, network-centric architectures is driving a number of design considerations for current and nextgeneration embedded COTS subsystems deployed on Unmanned Aerial Vehicles. The push toward network-centric architectures is speeding the adoption of these UAV platforms and newer data communications interfaces such as Gbit Ethernet, PCI Express, Serial RapidIO, and with discussion about migrating over to 10 GigE in the future. Many of the newer payload sensors are designed with high-speed ports to quickly transfer high-density data that's captured during mission in real time. At the same time, practical budgetary reasons for supporting slower legacy interfaces such as 1553 on the protocol level to protect software application development investment encourages continued but transitional support of earlier, slower aerospace interface standards.

During this period of transition away from legacy interfaces, UAV system integrators have taken a "best of both worlds"approach by, for example, supporting the simulation of 1553 over Gbit Ethernet and other highspeed interfaces. This encapsulation approach enables the system to utilize the entire 1553 structure and retain the software hooks that have already been built, tested and qualified for inf light applications.

In anticipation of future requirements related to network-centric architectures, next-generation UAV subsystems are being built today that incorporate the hardware piping that will utilize IP packet data in the upcoming future. This anticipatory step, essentially laying down high-speed "cables"while retaining support for application code that was written in legacy protocols, will ease the transition into adopting complete network-centric communications methodologies, including support for IPv6, when budgets allow and requirements demand the evolution.

As an example, Curtiss-Wright's SMU (Sensor Management Unit) (Figure 1) subsystem deployed aboard the Global Hawk UAV provides a fully modern platform with the capability to support Gbit Ethernet and High-Speed Fibre Channel links while interfacing with legacy interfaces such as 1553, RS-422, ECL and Fast Ethernet. In this way, the SMU works essentially as an interface fusion box, routing various interfaces and fusing them together.

The SMU's fully ruggedized aluminum chassis has also evolved from the original version (utilized in Global Hawk Block 20), adding significant ca- Val Zarov, Senior Program Manager Curtiss-Wright Controls Embedded Computing By integrating more powerful computer engines, along with speedy fabric interconnects, large UAV platforms are cranking up their sensor processing muscles to a new level. Large UAVs Ramp Up Sensor Processing Capabilities Slot-Cards in Large UAVs pacity for system expansion (planned for BAMS Global Hawk) while addressing demanding environmental requirements. Helping to drive this evolution has been an increased demand for modularity and scalability. UAV system integrators are being called on to enable both scaling up and scaling down of particular subsystems as required by the mission and payload configuration of other UAV platforms. This trend has driven designs to utilize VPX-based I/O-centric processors with multiple and widely supported high-speed fabric I/O interfaces and expandable high-bandwidth memory. Subsystems for the BAMS variant of Global Hawk, for example, will most likely include similar features.

Going beyond the idea of interface fusion, another new trend in UAV subsystem design is the requirement for data fusion. In data fusion, sensory data is fused with control data, enabling a subsystem to take image, radar, audio or inertial data and from it derive a control signal to a particular module. For example, BAMS Global Hawk (Figure 2) may be used by National Oceanic and Atmospheric Administration (NOAA) to study development of tropical depressions.

For this project, the UAV will fly above the tropical storm and drop temperature and pressure sensors into the weather depression. The idea here is to employ data fusion and artificial intelligence algorithms to autonomously deploy sensors at the exact time and location without human interaction. The image and other sensor data is fed to the Sensor Management Unit, where the data is processed and appropriate control signals are generated to deploy a particular payload.

Net-Centric Architectures
Another trend in UAV subsystem design is being driven by the adoption of network-centric architectures and the move toward higher bandwidth computing architectures. Today's UAV subsystems frequently utilize VME and/or CompactPCI-based architecture and the growing VITA 46 architecture. Curtiss-Wright's SMU, for example, employs a hybrid architecture that supports multiple bus types. To support network-centric methodologies that support multiple COTS processors and system scaling, system integrators want to move away from buses such as CompactPCI, which require a single processor to function as a host, controlling a number of slave boards.

The CompactPCI/VME model, in which the system controller (host) manages all other subsystem cards, burdens the host with processing that could otherwise be spread around different processors. This requirement is driving next-generation UAV subsystems to utilize fabric interconnect architecture, which does not require a dedicated system controller. Next-generation SMU will utilize Gbit Ethernet, PCI Express and Serial Rapid I/O for interboard/interconnect in a VPX form factor to achieve higher bandwidth requirements of a network-centric subsystem.

Unlike CompactPCI and VME, VPX advanced connectorization has the physical bandwidth to support dedicated pins for fabrics such as Gbit Ethernet, PCI Express and SRIO, which will enable the parallel processing and shared memory arrangements needed to meet heavy processing demand in a network-centric architecture in the future. An additional advantage of the VPX form factor backplane is that it provides a standard approach to wiring for Gbit Ethernet and other fabric I/O, defining and reserving particular pins for future growth and board interchangeability to address scalability/modularity and provide physical architecture for obsolescence management. This enables integrators to add or upgrade VPX boards for system expansion or upgrade, to achieve higher processing or add more memory, for example, without having to change the subsystem backplane or invest in costly system redesign.

UAVs: Critical Platforms
UAVs are increasingly critical platforms, both in theatres of combat and for national security, including response to natural disasters here at home. The Global Hawk, for example, played a key role in helping to locate hotspots to get fire fighting teams where they were most needed quickly, minimizing the spread of damage during recent forest fires in California. As they become more fully integrated into today's rapidly evolving network-centric architectures, the valuable data they can capture and distribute will deliver immeasurable dividends.

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