Abstract
The paper describes two methods of synthesizing feedback systems in which stability considerations are qualified by an overriding limit on power demand. The three basic requirements for either method are (a) a spectral density function of input signals, (b) a transfer function of fixed elements (i.e., basic elements essential for the performance of the task), and (c) the maximum rating of the power source. Examples are given. In one method the form of the stabilizing means has to be specified. The criterion, that the mean-square error be a minimum subject to the power limitation, is applied. This gives as a result the optimum design parameters of the specified stabilizing means. The other method, based upon the same criterion, uses a variational principle. A solution by this method gives a stabilizing means for the system which, within the specified power limit, cannot be improved. One example of this method illustrates the desirability of allowing a finite time delay between the input and the output of a feedback system.
