What is the primary purpose of a PID controller?

The primary purpose of a PID (Proportional-Integral-Derivative) controller is to maintain a desired output level by continuously adjusting the control inputs based on the difference between the desired setpoint and the current process variable. The PID controller achieves this by calculating an error value, which is the difference between the target state (setpoint) and the current state of a process.

The proportional component responds to the current error, the integral component addresses the accumulation of past errors, and the derivative component predicts future errors based on the rate of change. Together, these three components allow the PID controller to efficiently stabilize the process, minimizing overshoot and settling time, and keeping the output as close as possible to the desired setpoint.

Other choices relate to different functions that do not directly represent the primary purpose of a PID controller. While amplifying a signal, measuring temperature changes, or filtering noise can be important functions in various systems or sensors, they do not encapsulate the core functionality of controlling and stabilizing a system to achieve a specific output level.