More powerful. Lighter. Cooler. These are the key criteria for the design of Line Replaceable Units (LRUs) in next-generation Unmanned Aerial System (UAS) platforms, which continue to grow in importance to military organizations worldwide. The ability of these platforms to provide persistent surveillance of targets while eliminating the need to put warfighters in harm’s way makes them indispensable assets to commanders. The effectiveness of these platforms in the field is governed by their sensor payload and their processing systems. Next-generation UAS designs, such as the Navy’s Unmanned Combat Air System Carrier Demonstration (UCAS-D), require high levels of processing power for multiple onboard sensors, and all that power must be delivered in a lighter, cooler configuration that minimizes the size, weight and power (SWaP) envelope of onboard electronics subsystems.

COTSCurtiss- Wright Defense Solutions has supplied Northrop Grumman with the dual Integrated Mission Management Computer (IMMC) subsystems used as the redundant flight control processors aboard the Global Hawk UAS since the program’s inception in 2000.
Unfortunately, designing LRUs that meet next-generation UAS program requirements is a challenge. Commercial off-the-shelf (COTS) single board computers (SBCs) are available that provide key functionality for everything from feature recognition and video surveillance, to target identification and tracking. But not all SBCs are ideal for LRUs destined for new UAS platforms. Most do not have the processing power required. Some that do have the processing power require too much real estate in available chassis configurations, while others may offer the right mix of processing power and compact size, but cannot be cooled properly to meet rugged operational requirements. LRUs built on open architecture 3U VPX form factor modules offer the optimal balance of size, weight and power for a variety of UAS applications.

More Functionality in Less Space

Whatever the configuration of the sensor payload, the key to the effectiveness of a UAS once it is deployed is how long it can remain in the air collecting, processing and delivering sensor information to operators and commanders. If the payload is too large and too heavy, it will have an impact on fuel consumption and how long the UAS can stay in the air. Therefore, the more information processing that can be accomplished with smaller, more compact and more capable SBCs, the more valuable the LRU is to a system integrator and, ultimately, to the commander and operator in the field.

The compact 2-slot rugged 3U MPMC-9321 mission computer supports up to 2 single board computers or one SBC and one mezzanine card carrier board. (Curtiss-Wright)
New LRUs configured with SBCs built on the 3U VPX open standard offer a number of benefits. Compared to systems built on the 6U VME or even 6U VPX standards, LRUs configured with 3U VPX cards offer more processing power in a smaller form factor. As a result, system integrators need fewer cards and fewer LRUs in the same system to deliver the same functionality of a 6Ubased subsystem. For example, 6U VPX designs that may have previously required two LRUs can now be built with one LRU, thereby cutting size, weight and power allocations by as much as 50 percent.

Beyond functionality, 3U VPX SBCs are also a more cost effective option. With fewer SBCs needed to deliver the required functionality, development and build costs are lower. Once deployed, the open standard architecture makes life cycle maintenance and management easier, and makes tech insertion a less costly operation.

Pre-Validated Reference Design Architectures

Despite the benefits, leveraging the 3U VPX SBCs for next-generation UAS platforms can be difficult.

One of the biggest challenges that system integrators face is ensuring COTS-based SBCs will work as intended in a specific LRU design configuration. Like all COTS-based solutions, 3U VPX COTS SBCs are designed and built by COTS solution providers to perform a specific function, such as network routing, switching, or graphics processing. The manufacturer rarely knows how their board will ultimately be used in a LRU, and integrators can use the board to provide its function in a variety of LRUs destined for a variety of platforms. Often, the same board can be used in multiple LRUs to enable different applications.