There’s no doubt that there has been a change occurring in the military embedded computing industry over the past five years or so. At the heart of that change is the rising importance of the product category COTS Journal coined the “stand-alone rugged box.” In many ways these box-level systems resemble the end deliverable systems that prime contractor manufacturers pieced together with off-the-shelf subsystems inside it. But now these rugged box-level systems are a common COTS product offering among a wide selection of suppliers. In other words, they’ve become a second center of gravity alongside single board computers and slot card systems.

For years the SBC ranked as the driver of the military embedded computing market. When major vendors rolled out new SBC products—in VME, cPCI and other form factors—every couple of months, the peripheral, mezzanine and I/O products rode that wave, being sure to be compatible with whatever form factor or bus architecture the SBC vendors were supporting. That trend continues, but now integrated rugged box systems have started to move to the foreground as another choice for military system developers.

No Longer Just Custom

Rugged box-level systems typically comprise a set of modular embedded boards housed in a rugged enclosure that has its own power supply and interface ports to link to a variety of user terminals. And while the idea of offering a more complete system solution is nothing new, they used to be mostly “custom” offerings for specific customers. What’s changed, however, is that the concept has really become a kind of staple in this market, where even most board product suppliers now offer rugged box systems as catalog products. That said, there are a handful of companies, Crystal Group, Octagon Systems, Parvus, Quantum 3D, Rave Computer and RTD Embedded Technologies, that were doing this long before the traditional board vendors.

A key decision facing today’s military system developer is that of caged cards versus an off-the-shelf box-level computer. The traditional approach is to use slot card boards in a card cage. This means choosing a bus architecture, a rugged card cage and an SBC, plus any

additional I/O boards to fulfill the requirements. In the case of a tech refresh or tech upgrade program, the bus architecture is already given—VME being the most prevalent for military applications. More recently, for applications where size, weight and power have priority over past compatibility with legacy boards, the option of rugged box-level systems that are basically monolithic integrated computers is popular.

Trade-offs of the Slot Cards Approach

The slot card approach brings with it a number of merits. It offers the greatest flexibility in the I/O complement that can be supported. If an MIL-STD-1553 interface is needed, such a board can be added. This kind of flexibility is particularly useful when not all the I/O requirements are defined at the beginning of a project—a common situation in military programs. Some applications like comms and networking systems tend to require the slot card be available to the end-user for reconfiguring systems functionality in the field. Figure 1 shows an example of a 3U CompactPCI slot card system in the back of General Dynamics C4 System’s WIN-T demonstrator Humvee at AUSA Winter earlier this year.

On the downside, this means the system integrator is sometimes left to be the first to combine some of the board-level components and will have to work out any incompatibilities. Problems like mismatched drivers, variations in pin assignments and mechanical issues are all potential hurdles to overcome. In an integrated, box-level platform the supplier has already worked out these problems.

Predictability and Power

With an integrated rugged box-level computer many factors are known at the beginning. These include power, weight, heat dissipation and cooling strategy. The systems cable construction is also predefined as well as the basic level of operating system software. Generally speaking, a COTS rugged box system can be smaller, more power-efficient and more shock and vibration resistant than a slot card solution. 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. With the rugged box product category now well entrenched, a number of vendors are on their second and third generation of products. As this happens, products with more rigorous levels of ruggedization and environmental hardiness have emerged. 

Exemplifying this trend toward increasingly rugged solutions is Aitech Defense Systems’ NightHawk RCU (Figure 2). This Intel Atom-based box-level system is a self-contained control unit that weighs only 4.5 lbs. This weight reduction, combined with a slimmer profile and natural convection/radiation cooling that dissipates up to 22W at +55°C in stagnant (non-flowing) air, or at up to 71°C with an optional low pressure fan or baseplate, makes the rugged control unit ideal for a variety of military, aerospace and commercial environments. These include data concentrator and remote interface applications such as manned and unmanned, ground or airborne vehicles as well as low SWaP (size, weight and power) data concentrator unit (DCU) and remote interface unit (RIU) applications. For military tracked and wheeled vehicle applications, the NightHawk RCU can provide Condition Based Maintenance (CBM) functionality to reduce the overhead costs of preventative vehicle maintenance.

Based on the low-power Intel Atom processor operating at 1.6 GHz, the new NightHawk provides up to 2 Gbytes DDR2 SDRAM as well as between 4 and 8 Gbytes of SSD memory with an optional expansion up to 250 Gbytes for extended and remote data collection and storage applications. PC I/O interfaces are available in a low-power, environmentally sealed rugged controller. With a complete set of standard PC I/O interfaces, the NightHawk also provides two Gigabit Ethernet ports, six USB 2.0 ports and four multi-function RS-232 serial ports, dual graphics/video ports, keyboard/mouse and stereo audio in/output ports as well as an I/O set specifically tailored for embedded military and severe industrial applications. Optional I/O includes MIL-STD-1553B, ARINC-429 and ARINC-708, CAN Bus, Wi-Fi and WAN ports.

Also targeting the small size direction of rugged boxes is Crystal Group’s TCM2 (Tactical Computing Module). This embedded module is designed for Military shipboard, airborne and land-based applications. The TCM2 is a small-footprint (11” x 12.75” x 3”), high-performance embedded computer. It operates in extreme environments, offering extended capabilities with a temperature range of -40° to +65°C and 7.18 GRMS of random vibration. A standard 10-36 VDC power supply is included allowing it to run on conventional +12V vehicle power or +24/28 VDC, used in many military applications. It also comes with MIL-STD-461E filtering, allowing it to be integrated into existing platforms without disrupting nearby sensitive electronics.

The TCM2 embeds a dual-core 2.53 GHz Core 2 Duo CPU, up to 8 Gbytes of RAM, low-profile PCIe expansion capabilities, and two 2.5” rotational or solid-state hard drives. The TCM2 can also be configured with up to 8 additional 2.5” rotational or solid-state hard drives with the addition of a bolt-on expansion base. This effectively allows the TCM2 to offer up to 4.8 Tbytes of rotational hard drive storage or 1.28 Tbytes of SSD storage in a very small footprint, suitable for rugged embedded computing. The TCM2 also comes equipped with Military Circular MIL-C-26482 connectors, setting it apart from the existing TCM line.

Straddling the Two Approaches

While the rugged box-level approach and the slot card/card cage approach each offer advantages, there are likely to emerge implementations that take the best of both worlds. OpenVPX systems will likely take such a direction because military customers these days will expect both a high degree of pre-integration along with the ability to mix and match compatible boards. Enclosure and embedded board vendors have already started to team up along those lines. An early example was exhibited at the Milcom last fall where Curtiss-Wright Embedded Computing demonstrated a live OpenVPX system. The system (Figure 3) featured an OpenVPX backplane in a Hybricon SFF-4 Small Form Factor conduction-cooled chassis integrated with Curtiss-Wrights’ small form factor 3U OpenVPX-compliant cards, including single board computers, expansion carrier cards and graphics controller OpenVPX-compliant boards. The initial SFF-4 product is designed to support I/O for airborne and ground vehicle control applications, supporting I/O for Ethernet, serial, video and 1553 or CANBUS.  Different I/O complements can easily be supported with different backplanes.

Hybricon’s SFF-4 chassis is the first in a family of products and is designed for rugged environments for airborne and ground mobile applications. It provides support for the first industry available OpenVPX backplane and features extended temperature, shock and vibration tolerance. It is designed for use in MIL-STD-704F aircraft and MIL-STD-1275B vehicles.

Blade-Level Box Solutions

Another trend that straddles the box and slot card approach is the emergence of bladed server systems targeted for the military market. These solutions provide slot card flexibility in the form of blade compute nodes, but in a rugged box system that is designed for rugged applications. An example along such lines is Themis’ line of XR3 servers, which provide multicore processing, extensive I/O and storage options for high performance in compact, rackmountable 1U, 2U and 3U designs. Themis’ new XR3 series of Rugged Enterprise Servers (RES) combines the latest Intel Quad-Core Intel Xeon processors with the ruggedized design features of the Themis RES server family. Designed to perform in environments where other systems fail, the new RES-12XR3, RES-22XR3 and RES-32XR3 (Figure 4) servers blend the latest processor technologies with Themis’ proprietary thermal and mechanical design to deliver outstanding performance and reliability.

Offered in a compact 1RU, 2RU or 3RU short, light (20-inch aluminum) chassis, these new servers feature more memory—up to 144 Gbytes—and up to eight lockable and removable drives, hot-swappable fans and hard disk drives, single or redundant power supply options, and optional front panel filters for increased reliability in field deployments. These new systems combines the Quad-Core Intel Xeon 5500 series processors (Intel Nehalem Microarchitecture), with Themis’ advanced thermal and mechanical design techniques to provide users industry-leading SWAP (Size, Weight and Power), RAS (Reliability, Availability and Service), storage and I/O configurability.  

Aitech Defense Systems 
Chatsworth, CA.
(888) 248-3248.
[www.rugged.com].

Crystal Group
Hiawatha, IA.
(877) 279-7863.
[www.crystalrugged.com].

Curtiss-Wright Controls 

Hybricon
Ayer, MA.
(978) 772-5422.
[www.hybricon.com].

Themis Computer
Fremont, CA.
(510) 252-0870.
[www.themis.com].