Canada’s National Research Council Develops Revolutionary Aircraft Control System for Fly-By-Wire Rotary-Wing Aircraft

The technology will allow pilots to operate complex aircraft with a single pilot command interface acting as an independent controller of multiple input modes, simultaneously.

Ottawa-based National Research Council Canada Institute for Aerospace Research (NRC Aerospace) has developed a unique and revolutionary technology for fly-by-wire aircraft, which will allow pilots to operate complex aircraft with a single pilot command interface acting as an independent controller of multiple input modes, simultaneously.

This is a major breakthrough in the development of advanced aircraft control systems, allowing pilots to operate their aircraft to its maximum capabilities, more safely.

NRC’s novel technique blends rotorcraft control response types so that the frequency of the pilot’s input determines the control response type applied. With this approach, a pilot making slow/deliberate inputs, for example, those typically used in poor visual conditions, commands the aircraft via Translational Rate Control (TRC). Whereas a pilot using rapid control inputs, of the type more common in well-cued environments, channels the control input to attitude and rate command control systems. This control structure allows for the stability of a TRC system to be coupled with the performance of a rate command system without requiring discrete mode switching by the pilot.

NRC Aerospace Flight Research Laboratory (FRL) director, Stewart Baillie said, “Our researchers, Bill Gubbels and Kris Ellis, developed this technology over the last four years, and the results are truly revolutionary for pilots flying rotary-wing, fly-by-wire aircraft. This new control system architecture gives pilots stability when they need it and agility when they request it; all without making deliberate “mode-choice” decisions on what the situation demands.”

“I had the opportunity to fly this system in our technology demonstrator Bell 412 helicopter, and now I wouldn’t want to fly any other way,’’ he added.

In its development, the interface was tested at NRC Aerospace’s FRL in Ottawa, using its Bell 412 as a test platform. This new technology works by simplifying the aircraft control system so that in critical moments pilots can focus on flying rather than trying to manage a difficult control system with multiple discrete modes.

Rotorcraft require both the ability to maneuver aggressively and provide a stable platform. Pilots switch from quick aggressive inputs to slow deliberate inputs depending primarily on their ability to gain information through their visual external cueing. When there is a degraded visual environment such as “brownout” in sandy conditions, or ‘’whiteout’’ in the case of snow, higher levels of stability augmentation are desirable. These higher levels reduce the pilot’s workload by automatically balancing and counterbalancing the controls that stabilize the aircraft, but it also reduces the pilot’s ability to aggressively maneuver the aircraft. When visual cues are good, pilots can select lower levels of stability augmentation so that they can be more aggressive and precise in their handling.

NRC Aerospace’s new control system architecture consolidates both of these augmentation systems into one integrated system so that pilots no longer need to manually select to transition between these different response modes. In difficult situations these transitions can be distracting and take a pilot’s attention away from other important tasks. Significantly delayed transitions can result in damaged aircraft. For aircraft that operate in bad weather conditions or in combat operations, this technology could prove extremely useful. The single response mode provides both the stability of high augmentation responses, and the maneuverability of minimal stability augmentation, where possible.

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