The response of remote-position-control systems with hard-spring non-linear characteristics to step-function and random inputs

The paper is concerned with the response to step-function and random inputs of a closed-loop system having a specific class of non-linearity called ¿hard-spring.¿ In order that an analysis be carried out for step-function inputs the system is restricted to that with a second-order characteristic equation. Two amplitude characteristics are considered, the first being a continuous curve, and the second being composed of segments of three straight lines. An experimental system is described, and the results are compared with analysis. Stabilization is achieved by velocity feed-back, but derivative of error stabilization is also considered. A discussion of the effect of the non-linear characteristics on the overall stability of the system is included. The response of the system with the straight-line characteristics is obtained for random inputs and in the presence of noise. Detailed results and a discussion of their implications and value compared with transient and frequency-response testing are given. Theoretical verification is not included.