Dudley Nye, Nye Engineering Inc.

Fine tuning a PID tutorial

On the last page of the article ["Understanding PID Control," CE, June '00, pp. 53-58], the author stated that proportional-only control systems are incapable of hunting. This is only true if the process is a first-order time constant. (A single R-C time constant is a first-order delay.) If the process being controlled is second-order or greater, proportional-only control can result in ...