Block Diagram Models of Control System

By analyzing the block diagram, the following is obtained:

The feedback of the system is called negative feedback if the sign at the summing junction is negative and positive feedback if the sign is positive.

The block diagram of a closed-loop control system. The role of the feedback element whose transfer function is \(H(s)\) is to modify the output \(C(s)\) before it is compared with the input \(R(s)\). In most cases, the feedback element is a sensor that measures the output of the plant (process) \(G(s)\). The output \(C(s)\) of the sensor is compared with the system input \(R(s)\), and the actuating error signal \(E(s)\) is generated.