Rotorcraft–Pilot–Coupling (RPC) is a dynamic phenomenon in which the rotorcraft vibrations are transmitted through the cockpit, the seat and the control inceptors to the helicopter pilot and to the passengers. Handling qualities are affected by the proneness of the of rotorcraft to give rise to adverse interactions, an unwanted quality that can be captured by the so called biodynamic feedthrough. In this work, a multibody model of the whole upper body, developed by the authors, is used in order of evaluate the effects of several parameters influencing cockpit layout design: namely, the pilot seat backrest angle, compliance, and connection to the cockpit floor. The model comprises the complete upper body of pilot. Rigid bodies associated to torso sections, connected to nodes located in the respective vertebrae, are connected by linear viscoelastic elements representing both the passive and active (muscular) structural characteristics of the human biomechanics. Each upper limb is modeled through 4 rigid bodies, i.e. the humerus, the radius, the ulna and the hand, actuated by 25 muscle bundles. Dedicated procedures are used in solving the problem of estimating the biodynamic feedthrough, coping with the model kinematic underdeterminacy and overdeterminacy in the upper limb actuation. As a representative parameter of the flight controls design, the effects related to the characteristics of the trim spring is also investigated. Simulations encompass subjects of different anthropometric data, in order to represent possible intra-subject variations. Biomechanical feedthroughs at the collective and cyclic commands, estimated on the  response to vertical acceleration frequency sweep inputs in the range 0.5-12.5 Hz, are discussed, along with single-harmonic, high magnitude (9 m/s\^2) input responses that highlight the presence and importance of nonlinear effects. In the frequency sweep tests, the primary resonance frequency is in the range between 1.5Hz–2.1Hz with the exception of the case in which the seat compliance is neglected and the trim spring is engaged. In single-harmonic excitation tests, The phase diagrams, the time response and the frequency spectrum of the amplitude of each inceptors levers were evaluated and discussed. The collective rotation shows a nonlinear response when the trim spring is engaged and the seat compliance is considered. The cyclic lever exhibits a nonlinear behavior in all cases when the seat compliance is considered. In most cases the subject with lower BMI has a lower response amplitude, with the exception of the response of the cyclic lever without trim engaged, moreover having a backrest reclined of  
10 ◦ seems to have a beneficial impact on reducing the amplitude  
of the responses. In future developments, coupled simulations considering also the relevant rotorcraft dynamics are envisioned.


Effects of Flight Controls and Cockpit Layout Design in Rotorcraft-Pilot Couplings: A Computational Approach

Division / Sponsors: 
Design Engineering Division and Computers & Information In Engineering Division


Paper Proceedings: https://asmedigitalcollection.asme.org/IDETC-CIE/IDETC-CIE2020/volume/83907

IDETC2020 - Virtual Conference

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.