What role does a controller play in a closed-loop system?

In a closed-loop system, the primary role of the controller is to evaluate the process variable against the desired setpoint and make adjustments to the output accordingly. This function is essential for maintaining the system at its optimal operating conditions.

The controller continuously monitors feedback from the system, which represents the actual state of the process variable. By comparing this feedback to the predetermined setpoint, the controller determines whether the output needs to be adjusted to minimize any difference, known as the error. If the process variable deviates from the setpoint, the controller sends a corrective signal to the actuators or control elements that directly influence the system, thereby restoring the desired condition.

This dynamic feedback mechanism allows for precise control of the process, ensuring stability and proper operation under varying conditions. The effectiveness of the closed-loop control hinges on the controller's ability to respond quickly and accurately to discrepancies between the setpoint and the actual process variable.