THE HUMAN OPERATOR AS AN ELEMENT IN A CONTROL SYSTEM WITH TIME VARYING DYNAMICS,

In modern control system analysis, situations arise in which nonlinearities andor time variations make linear constant-coefficient representations inadequate. It follows that the ability of the human operator to control a system whose dynamics can be represented by linear differential equations with time-varying coefficients is now of more than just academic interest. To shed more light upon this subject, an experimental study was undertaken in which the human operator is presented with the task of controlling a system with linear, time-varying dynamics. More explicitly, the human is an element in a single axis, compensatory tracking system. Zero order periodically varying controlled elements are utilized as well as pure integrator elements in series with periodically varying gains. System inputs range from single sine waves to random appearing signals consisting of the sum of four sine waves. The possibility of representing the time varying system with an equivalent time invariant system is discussed and performance data is presented. Author