An optical pressure measurement system for control inceptors to evaluate pilots’ workload

Abstract: Understanding human-machine interaction is a fundamental research area in all engineering disciplines were the interaction between the user and the vehicle is central. From this point of view, aircraft in general and helicopters specifically offer a challenging test-bench: the interaction between the pilot and the helicopter is crucial tothe success of the flight missions. Furthermore, in some cases, the unwanted feedthrough of the aircraft accelerations at the control inputs can lead to adverse feedback loops, known as Rotorcraft Pilot Couplings (RPC) [1,2]. Since the pilot input is mediated by the control inceptors, measuring the pressure that the pilot’s hands exert on the inceptors’ grip can be very important in evaluating the mechanical impedance of the pilot, which can be correlated to the task workload [3]. However, Embedding existing measurement hardware inside the control inceptors grips may be challenging, or even impossible, without significantly altering the grip layout and thus introducing a possible source of discomfort for the pilot. These limits spurred the need to develop new measurement systems, that is able to - provide a reliable signal correlated to force exchanged between the hand and the grip; - be easy to be manufactured in such a way to be embedded in the grip, with as little loss in ergonomics as possible; - provide a signal that requires as little conditioning as possible.The solution proposed in this work has been called OPT-IN FCS (For OPTical-INceptors Flight Control System, Patent Pending) and is based on a well-known physical phenomenon commonly referred to as Frustrated Total Internal Reflection (FTIR). When an optical wave-guide, in which total internal reflection occurs, comes into contact with a third medium (outside of the wave-guide itself and air) a fraction of the incident radiation can propagate through the third medium. The paper will present the design and manufacturing of a full prototype of this device embedded in a control stick, and its application to a desktop simulator to monitor the hand activity for pilots during the performance of tasks with different levels of workload.[1] M.D. Pavel, M. Jump, B. Dang-Vu, P. Masarati, M. Gennaretti, A. Ionita, L. Zaichik, H. Smaili, G. Quaranta, D. Yilmaz, M. Jones, J. Serafini, J. Malecki (2013). Adverse rotorcraft pilot couplings—Past, present and future challenges, Progress in Aerospace Sciences, Vol. 62, 2013, Pages 1-51.[2] Quaranta, G., Masarati, P., Lanz, M., Marforio, M., & Muscarello, V. (2014). Biodynamic Adverse Rotorcraft-Pilot Coupling. In 5th International Conference on Applied Human Factors and Ergonomics (AHFE 2014), pp. 87-96.[3] Zanoni, A., Zago, M., Paolini, R., Quaranta, G., Galli, M., & Masarati, P. (2021). On Task Dependence of Helicopter Pilot Biodynamic Feedthrough and Neuromuscular Admittance: An Experimental and Numerical Study. IEEE Transactions on Human-Machine Systems.

Keywords: Human-Machine Interaction, Sensors, Helicopter Control Systems

DOI: 10.54941/ahfe1001154

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