Multibody dynamics analysis of the human upper body for rotorcraft–pilot interaction

The study of the biodynamic response of helicopter passengers and pilots, when excited by rotorcraft vibrations that are transmitted through the seat and, for the latter, the control inceptors, is of great importance in different areas of aircraft design. Handling qualities are affected by the proneness of the aircraft to give rise to adverse interactions, an unwanted quality that can be captured by the so-called biodynamic feedthrough. On the other hand, the transmissibility of vibrations, especially from the seat to the head, affects the comfort of pilots and passengers during flight. Detailed and parametrised multibody modelling of the human upper body can provide a strong base to support design decisions justified by a first-principles approach. In this work, a multibody model of the upper body is formed by connecting a previously developed detailed model of the arms to a similarly detailed model of the spine. The whole model can be adapted to a specific subject, identified by age, gender, weight and height. The spine model and the scaling procedure have been validated using the experimental results for seat to head transmissibility. The coupled spine-arms model is used to evaluate the biodynamic response in terms of involuntary motion induced on the control inceptors, including the related nonlinearities.