PIO I-II tendencies case study. Part 1. Mathematical modeling

Abstract

In the paper, a study is performed from the perspective of giving a method to reduce the conservatism of the well known PIO (Pilot-Induced Oscillation) criteria in predicting the susceptibility of an aircraft to this very harmful phenomenon. There are three interacting components of a PIO – the pilot, the vehicle, and the trigger (in fact, the hazard). The study, conceived in two parts, aims to underline the importance of human pilot model involved in analysis. In this first part, it is shown, following classical sources, how the LQG theory of control and estimation is used to obtain a complex model of human pilot. The approach is based on the argument, experimentally proved, that the human behaves “optimally” in some sense, subject to his inherent psychophysical limitations. The validation of such model is accomplished based on the experimental model of a VTOL-type aircraft. Then, the procedure of inserting typical saturation nonlinearities in the open loop transfer function is presented. A second part of the paper will illustrate PIO tendencies evaluation by means of a grapho-analytic method.