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The success of most military operations depends on the effective operation of different systems and tools in the field, and human-machine interfaces (HMIs) can significantly impact the performance of those military and aerospace systems. Effectively designed HMIs have made a vital contribution to the success of countless products across the spectrum of industries, ranging from the most sought-after consumer products to the most advanced military and aerospace equipment. But for military applications, the effectiveness and efficiency of an HMI is often a matter of life or death.

Aerospace applications range from cockpit controls and displays to cabin environment controls to in-flight entertainment systems. HMIs are used throughout defense and aerospace industries (Fig. 1), whether for shipboard, airborne, or ground-based mobile applications. These include hand-held computers, man-pack radios, high-resolution monitors, and secure voice/data communications devices. Because such hardware must withstand rough handling and extreme environmental conditions, such devices often require a ruggedized HMI for maximum performance.

Fig. 1HMIs for defense and aerospace applications must be designed to improve cognition and comprehension to enable rapid decision making. Thus, it is essential not only that information is clearly presented, but that inputs can be provided to a system without error—even under stressful conditions and situations.

Although an HMI may be viewed as an integral part of a military system, the design and manufacture of the interface is often a separate, specialized process that involves the highest levels of complexity (both human and technological). At the same time, build-to-print HMI designs created without the collaboration of an interface specialist is almost always fraught with problems.

Developing a successful machine interface involves design subtleties such as ergonomics, psychology and other “user-centric” considerations (Fig. 2). Plus, there is a host of available materials and interface technologies to choose from, the need to perform in harsh environments and, increasingly, the need to fit the most effective HMI within extremely limited space on smaller products.

Whether the interface is displaying information, collecting data, or controlling operations, it may require special design consideration such as ruggedized features or the integration of multiple elements into one. These are indicative of the many design challenges at the higher levels of complexity shared by HMIs.

Avoiding Design Pitfalls

Design engineers experienced in the development of HMI solutions often provide complete documentation for their designs. While a system may be well designed and documented, opportunities may be lost for reducing costs or gaining other benefits possible by consulting with HMI manufacturers prior to the completion of a system design.

As Keith Heinzig, vice president of engineering at Secure Communications Systems, observes: “There are serious challenges involved when customers build-to-print their own interface designs. Those include possible errors requiring redesign and additional time and money. Also, depending on the application, reliability is always a key constraint.”

Fig. 2Heinzig reports that engineers at Secure Communications Systems are not open to compromises that may impact reliability. The company provides custom rugged computer solutions and custom contract manufacturing solutions for defense, aerospace, and industrial applications that involve cold weather and other extreme operating conditions. Secure Communications Systems specializes in the integration of commercial-off-the-shelf (COTS) equipment into rugged, reliable, and cost-effective solutions.

“Our systems can be found in the hands of troops and on vehicles all around the world,” Heinzig notes. “Our commitment to providing high levels of service and quality has made us a long-term partner to many manufacturers in the defense industry.”

Early involvement during the design phase, and integrating all the various components of an HMI into a complete subassembly—including enclosures, displays, switches, and electronics—ensures that all the parts work in harmony to meet the required performance levels. The end result is a higher performing HMI that is easier for the end user to manage and integrate into their system.

Ensuring that interface devices are ruggedized for environmental conditions are a major concern in military and aerospace applications. This includes protection against corrosive environments, providing for ultra-rugged applications that require military-grade shielding, protection against shock or vibration, contaminate sealing, sunlight readability, night vision lighting and extended-life grade products.

Teaming with a firm with extensive expertise in the design and development of HMIs, such as Jayco mmi, Inc., can be instrumental in achieving a final system design with the performance and ease of use required for effective operation under severe conditions.

Fig. 3“We have worked successfully with Jayco for a number of years, and their preliminary design consultation has been very helpful in keeping us on the right track as far as planning and implementing the HMIs for our products,” Heinzig says. “Some of our more recent projects include very small controls, such as wrist displays for the military.

“The trend today is that products have to be smaller, lighter, and use lower power. Yet, you somehow have to find room to squeeze some HMI controls onto the equipment, and that gets more difficult as product sizes continue to be reduced.”

Heinzig adds that finding room for the HMI controls on the product often requires creativity and a bit of finesse. “It is often necessary to place the controls on the periphery of the product, and that requires advanced planning,” he says. Virtual prototyping aids in the process and shows exactly what is possible.

As an example of its many different HMI solutions, Jayco has developed an automatic weapon targeting interface for Soldier Enhanced Rigid Engagement and Vision in Ambient Lighting (SERVAL) systems (Fig. 3). This is a weapon-mounted interface that enables a soldier to quickly change imaging modes. The HMI must function under the most demanding environmental conditions, including at 40,000 ft. altitude and under 12 ft. of water.

The HMI switch assembly features MIL-I-46058C seal protection, with secondary conformal coating to MIL-I-46058 requirements around connectors for additional protection. The HMI is intelligently designed for ease and efficiency of use, and constructed to operate when needed, no matter how harsh the operating conditions.

Hemant Mistry, President

Jayco mmi, Inc., 1351 Pico St., Corona, CA 92881-3373; (951) 738-2000, (877) 529-2648

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