PC/104 remains the chosen solution for rugged vehicle applications
PC/104’s rugged capabilities and small form factor made it a preferred solution in defense (including onboard vehicle control and navigations systems), transport, and industrial control. Despite challenges posed to PC/104 from other architectures offering high computational performance within Small Form Factors (SFFs), PC/104 continues to flourish because of its flexibility in military and other rugged vehicle applications. It delivers high performance combined with low power, stackable configurations, MIL-STD compliance, as well as meeting key industrial and transportation standards.
The PC/104 standard is used widely as the basis for a range of CPUs and components for peripheral expansion, I/O, and power supplies. Characterized by a small (3.6" x 3.8"), stackable form factor and low power consumption, PC/104 has significant rugged benefits including the capability to withstand shock and vibration and tolerance of an extended temperature range (-40 °C to +85 °C). The ability to build stacks of PC/104 modules creates opportunities for developing a diversity of complex in-vehicle applications that range across industrial, transportation, and defense environments where PC/104’s robust and reliable capabilities are valued.
Winning the rugged module war
The defense sector has been a particularly strong arena for PC/104 products, which have created a greater acceptance of Commercial-Off-The-Shelf (COTS) solutions for military applications, with their modular benefits and proven reliability saving time and cost of project development. PC/104 combines a very rugged design with a very small footprint. Other standards demonstrate one or the other characteristic, but rarely both combined. PC/104 meets the critical survivability, performance, and interface flexibility requirements for military embedded systems, and these features have been validated over decades of experience.
New module standards released in recent years have been posing a challenge to the position of PC/104 in its traditional markets. In military electronics, Size, Weight, and Power (SWaP) is an all-important acronym leading to an increasing demand for small form factor board architectures. Both manned and unmanned applications are increasingly demanding the highest possible computational performance within dense, low-power solutions.
For instance, Computer-On-Module (COM) solutions evolved from PC/104, and in some cases, these have been deployed in rugged environments. These systems involve a complete computer on a single printed circuit board, including microprocessor, RAM, flash memory, Ethernet, and I/O controllers. Some of the more common COM modules include COM Express, ETX, Qseven, and many proprietary form factors.
However, there are concerns about the level of robustness of COM solutions. COM Express was not inherently designed with the same rugged qualities as the original PC/104, so for military and other applications experiencing high levels of vibration, COM Express modules may require additional testing whereas PC/104’s vibration resistance qualities are already well established.
3U VPX and VPX-REDI board standards are also major contenders for rugged SFF solutions for military applications. Offering exceptional performance, high density, and high bandwidth I/O, VPX and OpenVPX, also known as VITA 46 and VITA 65, use a high speed multi-GB connector to interface to a switched fabric backplane, and were developed with defense applications in mind.
VPX has made considerable developments in performance, but other open architectures like PC/104 will continue to be used for a range of budgetary and technical reasons. As VPX is ideally suited for sophisticated and high-power applications, VPX supports a greater power budget than legacy buses like VME, PC/104, and CompactPCI, but in many applications the extra performance is not needed and the potentially higher cost is not justified.
PC/104 answers the needs of a broad range of applications requiring a low-power, small form factor solution, and at a competitive cost. Both PC/104 and VPX have assured and continued roles to play in the defense sector, with PC/104 serving the low-to-mid market for military electronics while VPX covers higher end applications, such as complex high-value electronics required in military aircraft. With COTS driving a large part of military expenditure, the relatively low cost and rugged capabilities of PC/104 solutions make them a preferred option for military ground vehicle applications.
The fact that PC/104 is a modular system is a critical benefit, particularly for designers of military applications. Its ability to be far more flexible than other architectures is an invaluable characteristic, giving designers the ability to stack modules using a common core and add new functionality when and as needed. This capability to fine tune is not available to the same extent with other standards, and allows for systems to be modified and enhanced for changing operational requirements. It allows a military program to generate building blocks for problem solving, testing each stage of application development under operating conditions before adding a new element.
PC/104 in mil ground vehicles
Flexibility and its proven track record in military applications give PC/104 the edge for rapid completion of projects, such as meeting tight deadlines imposed by the UK’s Ministry of Defence Urgent Operational Requirements (UORs). For instance, recent production of a vehicle mounted data capture system for the British Army in Afghanistan was completed in only six weeks from initial order to delivery.
This data capture equipment covered many controls and functions within armored personnel carriers relating to communications, electronics, engine management, and a range of critical applications including the detection of Improvised Explosive Devices (IEDs).
The PC/104-Plus form factor processor board used featured a fanless design with an Intel Atom processor in a robust, ultra-small package providing exceptional connectivity and performance per watt. This combination of high performance and small dimensions made it ideal for use in an armored personnel carrier where space is at a premium.
In general, if a military vehicle has been installed with a PC/104 data logging solution initially, GPS can also be added with a link to the odometer to calculate distance and check speeds and use of gasoline. However, operations in the field might require greater sophistication. If the vehicle comes under attack in a theater of war, a camera and frame grabber module can also be installed in order to capture images and reconstruct the action. If an audio record is required, a PC/104 audio expansion module can be added. The same system can then be easily adapted for other types of military vehicle, such as adding further interfaces to control actuators and sensors in mine clearing units.
PC/104 in avionics systems
PC/104 is a reliable option for a variety of specialized applications, including those that involve MIL-STD-1553 communications. This is a military standard published by the U.S. Department of Defense (DoD) that defines the mechanical, electrical, and functional characteristics of a serial data bus. Its role in military avionics has been expanded with developments in the space program, and MIL-STD-1553 has also become commonly used in the On-Board Data Handling (OBDH) subsystems on both military and civil spacecraft. By choosing the PC/104 standard, designers can quickly add the MIL-STD-1553 bus to new and existing designs by plugging in one PC/104 add-on board. Other COM standards, like COM Express, do not map the MIL-STD-1553 signals on the standard connector pinout, effectively forcing developers to design and validate the interface themselves on the carrier board.
PC/104 can also be compliant with MIL-STD-810G, another popular requirement in avionics and in rugged applications in general: The U.S. Military Standard MIL-STD-810 (DoD Test Method Standard for Environmental Engineering Considerations and Laboratory Tests) establishes methods to test the limits of conditions that equipment can experience during its service life. MIL-STD-810G addresses a broad range of extreme environmental conditions and how they affect equipment operation, including resistance to temperature changes, humidity, sand and dust exposure, impact shock, and random or gunfire vibration.
PC/104 in rail applications
There are similarities in the performance requirements between a range of military and transportation applications, and PC/104 enables system design to meet the stringent qualifications for EN50155 (rolling stock) and MIL-STD-810G. EN50155 is the main technical standard covering electrified rail network applications, dealing with a range of constraints including:
- Surge requirements
- Electromagnetic interference
- Mechanical requirements
- Temperature/humidity resistance
- Galvanic isolation (namely isolating functional sections of electrical systems)
PC/104 solutions have been found to be ideal for a range of on-vehicle and trackside applications requiring high I/O density or high levels of insulation, including solutions for feeder driven trains and metros.
For instance, PC/104 provides dedicated add-on boards that deliver application-specific capabilities such as the Multifunction Vehicle Bus (MVB), a specialized fieldbus that is often used for digital control of the coach and includes applications such as control of doors, air conditioning, lights, and passenger information. In the locomotive itself, MVB is used to interface diagnostic systems, the cockpit, and important functions such as control of brakes, engine, power electronics, and track signals. This capability would require significantly greater efforts to implement with most other COM Standards.
Flexible and interoperable
The interoperability of PC/104-based solutions has allowed vendors to offer customers successful methods for updating the functionality of their legacy systems. For instance, Eurotech manufactures PC/104 products based on the Intel Atom and the DM&P Vortex86DX chipsets that deliver a feature set of a modern PC platform while retaining compatibility with legacy designs. In transportation, when dealing with onboard vehicle functions or infrastructures with long lifecycles, PC/104 solutions allow applications to be updated and different generations of technology to cooperate.
Eurotech has also developed cloud-based solutions that provide new opportunities to design flexible and scalable communications models between control centers and vehicles and assets in transport and military applications. As advances in technology continue, the original PC/104 concept remains fully viable and adaptive to change.
PC/104: Here to stay
PC/104 has stood the test of time and provides the invaluable features of rugged design in a very small footprint. In sectors like defense and transport it has gained customer confidence through proven operational capabilities in a variety of applications. The standard is unique in its level of flexibility compared to other architectures, allowinging tactical changes to be designed into systems, meeting operational imperatives, and saving time and cost.
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