Designing for Harsh and/or Rugged Environments
July 30, 2019
Rugged computers can be found in harsh manufacturing environments, automotive or other mobile/transportation applications, including aviation and rail.
A rugged industrial computer is one that’s designed specifically to operate reliably in a harsh environment and/or harsh conditions. That could be an environment that’s subject to lots of vibration, extreme temperatures, or wet or dusty conditions. Or it could be all of those at the same time.
Note that the military typically specifies that its platforms must adhere to strict rugged standards. A host of standards has been established by the military to guarantee compliance. Platforms aimed at industrial or other applications may or may not comply with those military standards. And other application areas have standards of their own. For example, the National Electrical Manufacturers Association, better known as NEMA, publishes a long list of standards that would apply to rugged computers.
The key to a rugged computer is that it’s designed for these environments from the get-go, rather than after the design is complete. While it may be possible to “sort of” ruggedize an existing non-rugged platform, that’s typically a recipe for failure. Don’t be fooled into thinking an enhanced commercial design will deliver the same performance as that of a true rugged industrial computer.
Another key to such a design is that the entire system must be designed properly, not just the single-board computer or some of the components on the board. And certainly not just the external case.
Rugged computers can be found in harsh manufacturing environments, automotive or other mobile/transportation applications, including aviation and rail. They can also be used in outdoor situations, like base stations or agriculture. Basically, any situation that’s moving, subject to extreme temperatures, or can potentially be used outdoors is subject to harsh conditions.
Another common term is “ruggedized.” This is often the condition mentioned above, where a non-rugged computer is adapted to operate in harsh conditions. It may contain an extra fan or have some adhesives added to seal the systems’ open seams. This works for some applications but if your platform will be subjected to a truly harsh environment, one that’s rugged, rather than ruggedized, is a better option.
A key element of a rugged computer is the elimination of moving parts. Instead of rotating hard drives, rugged computers have solid-state drives that are far more resistant to physical shock. They may have thicker PCB boards and can also contain stiffeners, often made out of aluminum, to prevent inside components and boards from flexing during an impact.
Conformal coating, which is typically a thin polymeric film, can also be applied to the PCB. As its name applies, the coating conforms to the contours of the board and serves to protect its components. It generally guards against moisture, dust, chemicals, and temperature extremes.
The outer case and bumpers should be designed to absorb the energy from vibration or a drop to prevent internal damage. Another measure designers should be on the lookout for are the Ingress Protection (IP) ratings, which define levels of sealing effectiveness for enclosures. This would be to ward off intrusion from things like dirt and moisture. Common IP ratings are 65, 66, 67, and 68. Here, the “6” represents an enclosure that offers full protection against dust and other particulates, including a vacuum seal, and is tested against continuous airflow. The second digit represents the level of moisture protection.
While some vendors claim their products are rugged, it’s a good practice not to take them at their word. Ask for detailed testing information from the manufacturer to verify the product's ability to operate in certain environments. And results can also be open to interpretation. Be sure to not only obtain the results, but to understand those results.
One good example of a product built to withstand harsh environments is the WINSYSTEMS’ PPM-C407 low-power SBC. In addition to its ruggedness, it adds long-term availability to its long list of features. That’s often a key ingredient in industrial designs. The PPM-C407 is designed with Intel’s E3800 family of Atom processors, which lets you choose between a low-power single-core and higher performance dual or quad-core solutions in the versatile PC104-Plus form factor. The rugged capabilities stem from having RAM soldered onto the board for added shock and vibration resistance. The SBC can operate from -40oC up to +85oC.
And if you’re in need of a touch-panel PC, check out WINSYSTEMS’ PPC65B-1x series, which is IP65-certified and optimized for use in demanding applications including industrial machinery, utilities, petroleum, transportation, pipeline, pharmaceutical and food processing. A key feature of the PPC65B is its minimal footprint without skimping on features. It takes advantage of an Intel 1.9-GHz Quad-Core Atom E3845 processor in a fanless design.
Remember: for harsh conditions, go with rugged, not ruggedized.