The Human Operator as a Sampled-Data System

Abstract

A sampled-data model of the human operator in compensatory tracking is proposed. The model assumes that the operator's behavior is characterized by sampling, data reconstruction and extrapolation operations. The spectral characteristics of the new model are presented. An experimental program was conducted to evaluate certain implications of the new model. The power spectral density of the tracking error was measured under a variety of conditions. The experimental results indicate that for inputs of sufficiently high bandwidth, the output and error spectra of human operators are characterized by sharp peaks which occur in the range of 1–1.5 cps. The correspondence of these spectral peaks to those produced by the mathematical model is discussed. Some preliminary results obtained while tracking with an intermittent display are evaluated on the basis of the model. In the concluding section of the paper the experimental results are compared with those predicted by the model. For the type of inputs considered in this study, the outputs from the discrete models approximate the experimental data more closely over a wider range of frequencies than those obtained from the quasi-linear continuous models previously employed to represent the human operator. COPYRIGHT © 1962—THE INSTITUTE OF RADIO ENGINEERS, INC.