The design of sampled-data feedback systems
V. Gladwyn Lago, G. John Truxal · Transactions of the American Institute of Electrical Engineers Part II Applications and Industry · 1954
SAMPLED-DATA feedback control systems, or pulsed servomechanisms, are characterized by the distinguishing feature that at one or more points in the system signal information is in the form of a pulse train which can be represented as a sequence of numbers. One example in which the signal information inherently is represented by a sequence of numbers is provided by a closed-loop system containing a digital computer as one element. Sampled-data systems are also useful when the energy available from a sensitive element is so small that it is imperative to avoid loading the output more than necessary.