Abstract
The frequency response of a linear digital control system is studied by simulating a plant (represented by a first-order lag plus dead-time) on the analog computer. The digital controller is simulated with analog track-and-store units and parallel logic components. The high speed of the analog computer allows it to display the sinusoidal signals on an oscilloscope in order to observe instantaneously the effect on the frequency response of changing various system parameters. This paper describes the simulation techniques we used, the results we obtained, and how the analog simulation helped us to get the "big picture" of the problem in only a few hours of simulation runs. We turned to analog simulation only after spending several months in an unsuccessful attempt to solve the problem by digital simulation. The reasons for this lack of success are cited.
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