what is the difference between Feedback controller and Feed
forward controller. and when it is to be used.
Answers were Sorted based on User's Feedback
Answer / jai
feed back controller is slow response ,feed forward is fast
response loop,becuae we are measuring the process value
before the control element.we can use wher we required fast
response.actually both loop prsent in the case cad control.
Is This Answer Correct ? | 27 Yes | 5 No |
Answer / vaishnavi
In the case of feedfwd controller we need to know the complete mathematical model and all the load variables acting on the process which is not possible and this takes anticipatory action b4 the disturbances can affect the process.
weras feedback control takes corrective action by measuring the error once the process is affected by load variables.and in this case we need not know the load var acting on the sys and no need for mathematical model.
hence usually feedfwd cant be used alone and is used in combination with feedback.
Is This Answer Correct ? | 18 Yes | 4 No |
Answer / muslim
feedback controller: to monitor the controlled variables
(pressure, temperature,..) and feedback the measured value
to the controller to be compared with set point within the
controller , and finally to give corrective signal used to
stabilize the control loop.
feedforward controller: to monitor all loads that influence
the process.
theoritically we have to monitor all loads, but practically
it's impossible .. as there's unmeasured disturbances (like
pipe fitting leaks, composition change ,..) that can't be
predicted.
so if we are to make a complete feedforward control so we
have no feedback mechanism and so we will have a non
disturbed process, which is impracticale.
practically we have feedforward in conjunction with
feedback control , which enhance the loop stability.
Is This Answer Correct ? | 15 Yes | 3 No |
Can please tell mi about SIOS, PRM, SERVER, and what is the diference between PIN LAN, PCS LAN,APC Server, and please send the Doc if possible for referance,mail id patil_amit17@yahoo.com
what is Instrumentation?
what is plc communication?
WHAT ARE THE INSTRUMENTAL DIAGRAMSOF VALVES?
0 Answers Artikal, ITC Infotech,
what's the criteria of using over range protector when installing Pressure Gauge
what the pid setting in controller
in a power plant main steam flow is volumetric or mass flow? is it required compensation?
how to check thermocouple ,its working or not?
14 Answers Coca Cola, Ford, Honeywell,
Linear amplifier.
the basic of a DP flow transmitter are the following
What should be the ideal tapping location for pressure differential transmitter for liquid service. If the tapping taken from the top of the pipe then PDIT will work properly or not. If PDIT do not work properly then what minimum corrective action should be taken in order to solve wrong tapping locations.
how can calibrate transmitter online