Generalized Control System

Command signal : It is the actual input excitation which is applicable to the system. Reference input element : This element converts the command signal to the form. ;
Reference input
t is the modified signal from command input and is applied to
error detector. It corresponds to the desired output.

Error detector : This element-compare the feedback signal with reference Input signal and produces resultant error signal.
Controller : This produces modified 01'manipulated signal which is further appliedh
the system.
Manipulated signal (m (t)) : It is the signal produced by the controller. It is writtenas
[m (t) or U (t) ] ·
Disturbance [d (t) J : It is undesirable signal acting on the system anywhere. It maybe
noise or other types of disturbances like wind etc.
Controlled
output [c (t) ] : The"-output signal from the plant or system-to-_be
controlled is called a control1 : ed output. It can be the desired output.
Feedback element : t is the element (transducer) which produces afeedback signalb (t)
proportional to controlled output and suitable for error detector.

Fèedback signal ) : It is the signal produced by feedback element and SUPP, lied toh
error detector.
Forward path : This is the generalised path from error or actuating signal to rbi
controlled output.
Feedback path : It is specific path from controlled output to the respective eMf
detector.