What type of feedback is typically involved in a closed loop control system?

In a closed loop control system, real-time performance feedback is essential for maintaining the desired output by continuously comparing it to the setpoint. This type of feedback allows the system to make adjustments based on the current performance of the process. Real-time feedback provides immediate data about the system's performance, enabling it to respond dynamically to changes in conditions or disturbances.

The nature of closed loop systems is to ensure that the controlled variable remains at the setpoint by incorporating this feedback to make necessary corrections. For example, in a temperature control system, a sensor measures the actual temperature and sends that data back to the controller, which then determines whether heating or cooling is required to maintain the desired temperature.

The other options do not align with the fundamental principles of closed loop systems: delayed output feedback does not allow for immediate correction of errors, unidirectional feedback would not provide the necessary input for corrective action, and no feedback at all negates the essence of a closed loop system, which relies on feedback for its functionality.