What is the function of a controller in a control system?

The function of a controller in a control system is primarily to process the error signal and control the process. The controller operates by comparing the desired setpoint with the actual process variable obtained from sensors, determining the error (the difference between these two values).

Once the error is calculated, the controller uses this information to determine the necessary actions to minimize the error and bring the process variable closer to the setpoint. This may involve sending control signals to actuators or other elements in the system to adjust the process accordingly. By continuously processing these error signals and adjusting the controls, the controller plays a crucial role in achieving and maintaining system stability and performance over time.

The other options presented relate to different aspects of a control system, such as initiating processes, gathering data, or regulating environmental factors, but they do not encapsulate the central role of a controller, which focuses on the feedback mechanism of processing error signals to ensure the system operates as desired.