SOLUTION

The use of the feedback element in the feedback loop is to converts the output variable ‘c’ to another suitable feedback variable ‘b’ to compare with the input command signal.

Detailed Explanation

Closed-loop control system

In this system, the control action is dependent on the desired output. Commonly the closed-loop control systems are called feedback control systems. Feedback allows the comparison of the output with input to the system so that an appropriate control action may be generated as some function of input and output.

It is divided into three basic components-feedback elements, controller, and controlled system.

Error detector or comparator: It is a device where the reference input and feedback signal are compared, and if there is a difference, an error signal is generated. Error signal:

Controller: Controller is a device whose input is the error signal and the output is the actuating signal. It acts to reduce the error to zero by making the actual output equal to the desired output. The controller essentially is a comparator.

Feedback element:– It is a device that converts the output variable ‘C’ to another suitable feedback variable ‘B’ to compare with the input command signal. This signal is used to compare with the reference input R. 

The feedback is a property of the system by which it permits the output to be compared with the reference input to generate the error signal based on which the appropriate controlling action can be decided. The purpose of feedback is to reduce the error between the reference input and the system output.