Effects of biodynamic coupling on the human operator model

Abstract

Describing function models of the human operator in manual tracking tasks developed so far, have essentially been restricted to a static cockpit environment using fixed based simulators. This paper addresses the problem whether, and how, the response of the human operator and his associated describing function are influenced by cockpit motion induced by his own control commands. It is suggested, that the motion induced biodynamic stick feedthrough affecting the inner kinesthetic control loop, can be interpreted as a modification of the dynamics of the controlled vehicle. By assuming that the crossover model remains valid under conditions of vehicle motion, an extended analytical model of the human operator describing function is derived. Computer simulation of this analytical model provides reference characteristics of the describing function and remnant noise. A validation of this model, accomplished by extensive dynamical tests on a moving base simulator is described. The excellent match of the analytical and experimental characteristics obtained both in magnitude and shape substantiates the notion of the extended human operator model and suggests that it may contribute to improved overall pilot-aircraft system design.