The human operator as a servo system element

doi:10.1016/0016-0032(59)90091-2

Journal of the Franklin Institute

Volume 267, Issue 5, May 1959, Pages 381-403

https://doi.org/10.1016/0016-0032(59)90091-2 Get rights and content

Abstract

This paper considers the role of human elements in certain closed loop control systems. A quantitative description of human dynamics useful to control system designers is essential to understanding and analysis of such systems. Accordingly, the human behavior description must be expressed in terms which are compatible with conventional descriptions of control system components. This compatibility is achieved by the use of a quasi-linear mathematical model for the human operator. The model is composed of two components—a describing function and remnant. The describing function, which for a linear system is identical with the conventional transfer function, is established to characterize that portion of the operator's output which is linearly correlated with his input. The input, upon which the describing function is based, is selected on the basis of a priori estimates of the nature of certain human non-linear behavior. Human output power which cannot be characterized by the operation of the describing function on the input is designated as the remnant.

After presenting the analytic basis for measurements of human dynamics, steady-state describing functions measured by the various experiments in the field are discussed and the adaptive, optimalizing behavior of the human operator is demonstrated. The remnants are also discussed and plausible sources for their origin are postulated.

Knowledge of the range of parameter adjustment of which the human operator is capable in his adaptation as well as knowledge of his criteria for adjusting these parameters enables the designer to specify input functions and operator controlled dynamics compatible with both desirable human operator behavior and good system performance. By judiciously trading off system complexity against operator preferences, while still making proper engineering use of the human operator's adaptability, a control system may be optimized for both performance and reliability.

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^☆: This research was supported in whole or in part by the United States Air Force under Contracts AF 33(616)-3080, AF 33(038)-10420, AF 33(616)-2804, AF 33(616)-3610, and AF 33(616)-5822, monitored jointly by the Flight Control Laboratory and the Aero Medical Laboratory, Wright Air Development Center, Wright-Patterson Air Force Base, Ohio.

¹: Systems Technology, Inc., Inglewood, Calif.

²: The Franklin Institute Laboratories for Research and Development, Philadelphia, Pa.

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The human operator as a servo system element☆

Abstract

Dynamic Response of Human Operators

WADC TR 56-524

The Human Pilot

The Human as a Dual Mode Relay Servomechanism

Nonlinear Techniques for Studying Human Operator Performance

The Phase-Plane as a Tool for the Study of Human Behavior in Tracking Problems

WADC TR 55-444

A Nonlinear Approach to Human Tracking

Franklin Institute Report I-2490-1, Contract Nav 1571(00)

Combination Open-Cycle, Closed-Cycle System

Introduction to Nonlinear Mechanics

The Analysis of Nonlinear Control Systems with Random Inputs