Simulation of digital control systems on an analog computer with digital logic

This paper describes a procedure for simulation of digital control systems on an analog computer with digital logic. The digital elements are only those normally provided in the digital panel now available as an optional accessory from most analog computer manufacturers. When used in conjunction with the conventional analog amplifiers and integrators connected as track-hold devices, it is possible to simulate complete systems which include not only the straightforward single-rate system but also those having two or more sampling rates or subsystems, and those having delayed or skip sampling characteristics. The digital logic connections for some simple but typical problems are given and are suggestive of those required for more sophisticated applications. A couple of oscilloscope photographs are included which show the informative presentation which can be obtained with this simulation technique.