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There's no avoiding the trend toward processors and other key components ramping up in wattage. And more power means more challenges dissipating heat. Rugged box-level systems are now available that address these problems themselves. Exotic techniques such as spray-cooling and liquid-cooling are all on the table as possible ways to attack the cooling challenge. Meanwhile, clever new mechanical designs that maximize system-wide conduction-cooling are equally important.
In tandem with the military's drive toward greater compute density, there's a growing demand to reduce size, weight and power (SWaP) of system electronics. More and more programs are pushing for as much computer processing muscle as can possibly fit into a board-level solution. Driving those demands is a desire to fit more functionality in the same space or into a smaller footprint. In the air, this means smaller and longer endurance for systems like UAVs. For ground vehicles this means more weight can be allocated to the all important armor of ground vehicles.
New Twist on the Problem
The emergence of rugged box-level systems has brought different twists to the size, weight and power problem. Over the past couple years, stand-alone rugged box-level systems have become one of the fastest growing areas of military embedded computer design. These complete system boxes-which often support standard form factor boards inside them-provide a complete, tested and enclosed computing solution that eliminates complex integration chores for customers. Today dozens of vendors have some sort of stand-alone rugged box-level system in their offerings-many even have whole product lines in that category. Among these are Acromag, Advantech, Aitech Computers, Ampro Computers, AP Labs, Curtiss-Wright, DRS Technologies, Extreme Engineering, General Micro Systems, GE Fanuc Embedded Systems, Macrolink, Mercury, MEN Micro, Octagon Systems, Parvus, Quantum 3D, Rave Computer, RTD Embedded Technologies, VersaLogic, WIN Enterprises and WinSystems.
A new set of challenges faced by defense programs has driven the rugged requirements for defense electronics to new levels. Defense forces are meeting the need for more intelligence-gathering assets by placing sensors on unmanned vehicles (UVs)-which are airborne (UAVs), ground-based, or undersea. Early implementations such as the Global Hawk and Predator UAVs were fairly large platforms, but each succeeding generation is smaller. The challenge is to make the sensor-supporting processing power fit into a smaller size, weight and power (SWaP) budget. These smaller computing packages must also be rugged enough to withstand operation within deployed UVs.
Since cooling is directly related to SWaP in many cases, the term SWaP-C is now widely used to describe these governing constraints. This is especially true for ground vehicle, UAV and manned aircraft applications, where tight spaces, operational demands and payload parameters must be factored into the final system solution (Figure 1). As these constraints have gotten tighter, electronics systems also are often being designed to perform multiple tasks, rather than having multiple systems dedicated to separate tasks. While a consolidation of functions can help to conserve overall space in the vehicle, it places even more demands on the primary system thereby further driving up performance, storage, cooling and reliability requirements.
UAVs like the MQ-9 Reaper are driving the need for compact, low-power box-level solutions. Shown here preparing to land after a mission in Afghanistan, the Reaper has the ability to carry both precision-guided bombs and air-to-ground missiles.
Often times a stand-alone rugged box system can be smaller, more power efficient, more rugged and so forth, if only because of its broader utilization compared to a purpose-built computer. If the box-level system supplier is building the platform all the time, to fulfill demand, one can be pretty confident in their procedures and outcomes, compared to the early specimens of a project-specific computer. Finally, once the deployment has reached an appreciable size, it may be a welcome luxury to regard the computer as a single LRU, and just return it for service when necessary, instead of owning fault isolation down to the board level.
The stand-alone rugged box trend has pervaded all corners of the military embedded computing space. Many product lines have even moved on to second-generation, smaller spin-off versions. An example along those lines is Mercury Computer Systems' new, rugged, manpack-sized system. Enhancing the Ensemble 1000 Series family of computing systems, the 2-slot PowerBlock 15 has a convection-cooled or cold-plate mountable design, suitable for deployment on small platforms operating in harsh environments. Approximately the size of an external hard drive, the portable system can be configured with any of the processing, I/O, or storage modules currently used in the 6-slot PowerBlock 50 chassis.
Ensemble 1000 Series systems, using either the PowerBlock 15 (Figure 2) or the PowerBlock 50 chassis, are scalable and optimized for real-time applications. A point-to-point PCI Express connection delivers high-throughput, non-blocking, serial connectivity between processing and I/O nodes. External I/O can be customized to accommodate virtually any type of digital or analog I/O. Processing options include the Intel EP80579 SoC (system-on-chip) device, Xilinx Virtex-4 and Virtex-5 FPGAs, the AMD M96 GPU (Graphics Processing Unit), and Freescale PowerQUICC processors, all supported by SATA hard-disk and solid-state storage drives.
Approximately the size of an external hard drive, the 2-slot PowerBlock 15 has a convection-cooled or cold-plate mountable design, suitable for deployment on small platforms operating in harsh environments.
Another significant challenge is driven by changes within computing technology. New components, especially processors, are orders of magnitude faster, but they are also much, much hotter, magnifying the cooling challenge. In the early 90s a 66 MHz CPU consumed about 7W of power. In an office environment it would not even need a cooling fan. Now processors will often draw over 50W, sometimes over 150W, depending upon clock speed, core type and processing load.
How OpenVPX Fits In
With all that in mind, defense program teams have a situation requiring that much hotter, albeit faster, components must operate with increasingly difficult SWaP restrictions. Meeting this new level of challenge requires a systems-level approach to solutions design. A broad range of applications can be addressed by a more rigorous, standards-based approach. The evolution of the OpenVPX standard is proving to be a great benefit to this systems-level approach. Created to improve interoperability of off-the-shelf modules, OpenVPX does this by implementation of predefined system topologies that simplify integration of components while retaining a significant range of configuration flexibility.
When programs reach the stage for integrating a deployable system, OpenVPX leverages the VITA 47 and VITA 48 standards. Designs can be optimized at the systems level for ruggedness and cooling, while the use of standards-based components-modules and chassis-reduces the integration effort and speeds time-to-deployment. Adhering to a systems level approach based on open industry standards gains these advantages while retaining a large degree of design flexibility.
An example of this new generation of VPX-based, compact, power-friendly box-level systems is an 8.8 pound sub-½ ATR, forced air-cooled enclosure for conduction-cooled modules from Extreme Engineering Solutions. Called the XPand4200 (Figure 3), a fully populated version weighs less than 15 pounds and is suitable for C4ISR applications in vehicles such as UAVs, helicopters, planes, tanks and light armored vehicles, HMMWVs and UGVs. The XPand4200 conducts heat from conduction-cooled modules to heat exchangers, where the heat is dissipated to the ambient environment by forced air cooling. The system measures 4.88 x 6.0 x 13.5 inches.
The XPand4200 system weighs less than 15 pounds fully populated. It conducts heat from conduction-cooled modules to heat exchangers, where the heat is dissipated to the ambient environment by forced air cooling. The system measures 4.88 x 6.0 x 13.5 inches.
Up to six conduction-cooled, 0.8" pitch 3U VPX, 3U cPCI, or power supply modules can be configured into the XPand4200. Additionally, the XPand4200 can be configured to meet custom I/O requirements with conduction-cooled PMC/XMC modules available from X-ES or third parties. The XPand4200 supports Gigabit Ethernet, graphics, RS-232/RS-422, MIL-STD-1553, ARINC 429, as well as custom conduction-cooled PMC/XMC I/O through D38999 circular connectors. An optional front-panel USB port provides system monitoring and maintenance capabilities. There are several power supply options, supporting up to 200W from a MIL-STD-704 28V DC or 115V AC input, as well as internal EMI filtering and hold-up for up to 60 ms at 200W.
San Jose, CA.
Curtiss-Wright Controls Embedded Computing
Extreme Engineering Solutions
GE Intelligent Platforms
Mercury Computer Systems
Salt Lake City, UT.
San Jose, CA.
Liberty Lake, WA.
N. Andover, MA.