Nonlinear Computations in the Human Controller

The response of the human forearm following random input step commands was observed to approach at its best the same kind of response as that of a maximum-effort minimum-time optimum bang-bang servo in which the magnitude of the error is compared with a nonlinear function of the stored energy in the load. Tests were made which required the hand to move both small and large inertias, small and large friction coefficients, and small and large springs, with combinations of these. The muscle force was calculated and plotted as a function of time for a great many tests on different individuals. This paper will not describe the average response, but the best response which any individual is capable of achieving. The muscle forces were relatively constant for each individual regardless of the dynamics of the load or the magnitude of the command.