Biomechanical models for vibration feedthrough to hands and head for a semisupine pilot.

A series of tracking experiments under vibration has been carried out on the AMRL/BBV shaker facilities covering three axes of vibration with sinusoidal and random waveforms and different control stick configurations. Based on this and other data, a lumped-parameter biomechanical model has been evolved to suit the needs of aircraft control system designers for the new generation of low-altitude, high-speed bombers and highly maneuverable fighters. This paper shows that measured vibration feedthrough to hands and head can be adequately described by this model when linearized about the appropriate configuration of display, posture, and control. The model includes effects of: semisupine torso; sliding hip, plus rocking chest supported on a compliant buttocks/seat; head bobbing on an articulated neck; upper arm and forearm links plus grip-interface compliance, driven by an active neuromuscular system; elbow rest (optional); and stick "feel system" dynamics. Examples are given of the model's application to predict effects of: a 65 degrees semisupine seat, apparent impedance increase of a control stick under pilot control, and a sliding arm rest.