What type of closed-loop system adjusts the output of a process based on the difference between the desired output and the measured output?

The correct answer is that the type of closed-loop system that adjusts the output of a process based on the difference between the desired output and the measured output is feedback control.

Feedback control systems are designed to constantly monitor the output of a system and compare it to a desired target or setpoint. The key aspect of this system is the feedback loop, which uses the error signal — the difference between the desired output and the actual output — to make real-time adjustments to the system. This process allows the system to respond dynamically to variations and maintain stability and accuracy in its performance.

Other control strategies, such as proportional and proportional-integral-derivative control, are types of feedback control, but they include additional calculations or adjustments to enhance performance. Proportional control adjusts the output proportionally to the error, while proportional-integral-derivative control combines proportional control with integrative and derivative actions to provide a more sophisticated response to varying conditions.

In essence, while feedback control encompasses a broad range of methods, it fundamentally relies on the principle of continuously comparing the output against a desired target and making adjustments based on that comparison.