Motion Fidelity Assessment for Helicopter Simulations

Abstract

The Objective Motion Cueing Test (OMCT) refers to a way to measure motion characteristics of a simulation objectively, by constructing so-called frequency response functions of the cueing system. Research in recent years has applied the OMCT to a number of fixed-wing research simulators. However, the effect of aircraft dynamics on predicted motion fidelity of the OMCT is poorly understood. The goal of this research therefore is to increase the understanding of the OMCT, by applying it to helicopter simulations. From literature, it was found that abstractions on the input signals of the OMCT may affect the representativity of predicted motion characteristics. As a first step in this thesis, the effect of these assumptions on the predicted motion characteristics of the OMCT was studied. It was seen that the current OMCT has a set of input signals which may be representative for heave motion, but might not be representative for pitch and surge motion characteristics. Therefore it was investigated whether a potentially superior OMCT, better representing helicopter motion, can be defined. An OMCT was tailored to longitudinal helicopter motion. Notable differences in pitch and surge motion characteristics were found. However, for pilot-in-the-loop training, the aircraft motion does not only depend on the dynamics of the aircraft model, but also on pilot input. Therefore, using pilot-in-the-loop simulation data, the effect of manual pilot control behaviour on the proposed methodology was studied. It was seen that, although differences were identified, the main trend of the frequency response functions was determined by the dynamics of the helicopter model, not the pilot input. Further research is recommended to evaluate the current set of input signals of the OMCT for a variety of models, also incorporating lateral motion, and tasks using a similar method presented in this thesis.