ABSTRACT
All controllers must be adjusted or tuned to accommodate the processes they control. There are several approaches to this task. Some of the techniques are mathematical. The purpose of tuning a controller to a process is to match the gain and time functions of the controller with the rest of the elements in the control loop. The object of adjusting a controller's proportional band is to give the total loop a dynamic gain of less than 1 in order to force any induced upset to dampen out. The closed-loop cycling method uses a process-control loop that oscillates at a gain of 1 in order to predict all mode settings. A typical tuning procedure would be: Set the integral to maximum time, Set the derivative to minimum time, Set the proportional band to maximum, Place the controller in automatic and Measure the loop's time period.
