Classification of Control Systems

Control systems are classified into two general categories based upon the control action which is responsible to activate the system to produce the output viz.

<!--[if !supportLists]-->1)      <!--[endif]-->Open loop control system in which the control action is independent of the out put.      

<!--[if !supportLists]-->2)      <!--[endif]-->Closed loop control system in which the control action is some how dependent upon the output and are generally called as feedback control systems. 

Open Loop System is a system in which control action is independent of output. To each reference input there is a corresponding output which depends upon the system and its operating conditions. The accuracy of the system depends on the calibration of the system. In the presence of noise or disturbances open loop control will not perform satisfactorily.