Transfer matrix stability criterion applied to an amplidyne servo network

The problem of stability rightly enjoys a central role in the theory of servomechanisms. In this paper the transfer matrix stability criterion1 is applied to an electromechanic servo system employing an amplidyne as the amplifying element. This criterion is valid for either exact neutralization, the strict amplidyne amplifier (in which case a unilateral feedback loop ensues) or for over- or under-neutralization, the Metadyne amplifier (which results in a bilateral transmitting feedback loop). Both cases of neutralization yield substantial agreement between the mathematical predictions and the physical performances, with allowances for the necessary idealizations introduced to render the analysis tractable.