What does "feedback" mean in a control system?

In a control system, "feedback" refers to the process of using the output of the system to influence the system's input. This mechanism is fundamental in maintaining control and stability within the system. When feedback is positive or negative, it allows for adjustments to be made based on the performance of the output relative to the desired setpoint. For instance, in temperature control, a thermostat might measure the current temperature (the output) and compare it to the desired temperature (the input). If the output deviates from the desired setpoint, the system adjusts accordingly, demonstrating how feedback plays a crucial role in ensuring that the control system operates efficiently and effectively.

The other options do not capture the essence of how feedback operates in a control system. For example, disregarding the output would mean there is no adjustment based on performance, while controlling the system without any input suggests a lack of interaction between input and output, which is contrary to the principles of feedback. Storing data for future reference might be useful, but it does not directly correlate to the real-time responsiveness that feedback provides in a control system context.