What is the proportional function of a controller also known as?

The proportional function of a controller is referred to as "Gain." In control systems, gain defines how much the output of a controller will respond to a change in the input signal, which is a crucial aspect of system performance. When the error (the difference between the desired setpoint and the actual process variable) is multiplied by the gain, it determines the output signal of the controller. Essentially, gain controls the magnitude of the output response to the measured error; a higher gain results in a more aggressive response to errors, while a lower gain results in a more subdued response.

Understanding gain is vital for effective tuning of control systems, as it directly influences stability and responsiveness. In a proportional controller, the control action is proportional to the error signal, making gain a foundational concept in PID (Proportional-Integral-Derivative) controller design.