Project Abstract
Several components are used to supply a pressurized oxygen/air mixture to pilots of high-performance military aircraft for breathing during high altitude flight. The dynamic interaction between these mechanical components must be well-matched to support the physiological needs of a pilot over a wide range of operational and environmental conditions. An additional complication is the interaction of this machine with a wide range of human respiratory system characteristics presented by the aircrew population. (e.g., various lung volume, lung tissue elasticity, diaphragm muscle elasticity, airway flow resistance, etc.). Unintended dynamic interactions between these systems could adversely affect a pilot’s breathing and be a contributing factor in the numerous reports of unexplained physiological episodes (UPEs). The complexity of these human–machine interactions and the unforgiving environment in which aircrews operate requires a unified, systematic approach to identify unintended system interactions. A model that captures the interaction between the key elements, notably the pilot’s respiratory mechanics, the physical dynamics of the mask, and any significant response characteristics of life support systems, can augment understanding of the system dynamics.
The primary goal of this research is discover any unexplained physiological episodes caused by currently unknown adverse dynamic interactions within the complex system of systems providing life support to the pilot and/or aircrew of high performance military aircraft. To achieve this goal, the following aims must first be realized: 1) Develop a respiratory mechanics model of the human lungs capable of interacting with the passive mechanical life support hardware used by pilots and aircrew of high-performance jet aircraft (i.e. fighter jets). 2) Develop dynamic models of the various mechanical systems that comprise the life support system for the fighter pilot. Each system element (breathing regulator, supply hose(s), inhalation valve, oronasal mask, and exhalation valve) may have more than one model “descriptor”. For some elements, where a large variety of configurations are used in different aircraft, a representative configuration will be selected for the investigation. 3) As the complete dynamic system model is quite complex, requiring the solution of 20+ simultaneous differential equations, a methodology to strategically couple the physiological human respiratory mechanics model to various levels of mechanical life support hardware model fidelity/complexity is introduced. The value of this methodology to investigate potential undesirable dynamic interactions between the human and the support hardware as well as between various elements of the support hardware is demonstrated. The bond graph is shown to be an effective method of illustrating the relative complexities of the various model structures as well as facilitating the proper connection between the various modeling elements.
An anticipated outcome of this investigation is a dynamic modeling tool that can be used to guide the design of the next generation of respiration masks to reduce the work of breathing required by the aviators to perform their missions.
People
- Mark Koeroghlian (PhD, December 2021) – A dynamic model of human respiratory mechanics for use in respiratory mask design and development
Publications / Products
- Koeroghlian, M.M., and R.G. Longoria, “Breathing Through a Positive-Pressure, Demand-Flow Life Support System: A Conceptual Dynamic Model”, SAFE Journal, Accepted for publication, February, 2022
- Koeroghlian, M.M., and R.G. Longoria, Dynamic Modeling of a Combat Pilot’s Breathing Support System, 59th Annual SAFE Symposium (Systems Integration session), Mobile, AL, November 2-4, 2021 (presentation)
- Mark M. Koeroghlian and Raul G. Longoria, “Bond Graph Model of a Fighter Pilot’s Breathing Support System”, 2020 International Conference on Bond Graph Modeling and Simulation (ICBGM), San Diego, CA, October, 2021
- Mark M. Koeroghlian, Steven Nichols, and Raul G. Longoria, “A Respiratory Mechanics Model of the Human Lung for Positive Pressure Breathing at High Altitude”, ASME Journal of Dynamic Systems, Measurement, and Control, Vol. 142(10), October 2020. https://doi.org/10.1115/1.4047220
