What is open loop &closed loop system?

Open loop control system does not involve the feedback taken from the output response due to an input where as in a closed loop control system the feedback from output is considered and an error value is calculated by substracting the desired setpoints from the actuall output value.

Openloop control system does not need any feedback from output. Where are closeloop system requires.

open loop control system which not feed back sent and close loop control feed back sent the controller

In the system the output quantity is not depend upon input quantity is called open loop and its oppsite input is required for desired output is called closed loop.

am i right

OPEN LOOP CONTROL SYSTEM:-

*It loop or path is open.

*In this control system  input has no control over output .

*In this control system mv value are adjusted once not readjusted continually to maintain the pv into        sp when disturbance disturb the pv.

CLOSE LOOP  CONTROL SYSTEM:-

* It loop or path is close.

*In this control system, cv are measured and feed back to the controller through a path.

*In this control sysytem  input has control over output .  

*In this control system  controller take care against the all type of disturbances.

NOTE:-

* pv or cv  = speed of moter

* sp =1500rpm

*mv= voltage

*disturbance-lood,bearing,condition,etc.

In close loop systems feedback is taken from output as error which will be added or subtracted to/from input and then given to system while open loop is based on pre-calculation only, no feedback is added or subtracted to/from input signal.

Open loop no feed back no ctrol on o/p

closed loop control o/p by control feed back 

main purpose for clsed loop to make zero error "difference between desired o/p and actual o/p"