Feedback Control vs Feedforward Control-Difference between Feedback Control and Feedforward Control
This page compares Feedback Control vs Feedforward Control and mentions difference between Feedback Control and Feedforward Control. It mentions advantages and disadvantages of Feedback Control system and Feedforward Control system.
Feedback Control System
• In feedback control system, the output of the process is continuously compared with input of the process.
If there is any deviation between them, the error signal is generated which is sent to the controller.
• The controller tries to bring back the process to the desired level with the help of final control element. The figure-1 depicts generalized process in a feedback control loop.
Advantages of Feedback Control System
Following are the advantages of Feedback control system:
➨It does not require identification and measurement of any disturbance.
➨It is insensitive to modeling errors.
➨It is insensitive to parameter changes.
Disadvantages of Feedback Control System
Following are the disadvantages of Feedback control system:
➨It waits until the effect of the disturbances has been felt by the system before control action is taken.
➨It is unsatisfactory for slow processes or with significant dead time.
➨It may create instability in the closed loop response.
Feedforward Control System
• A feedforward control configuration measures the disturbance directly and takes the control action to eliminate its impact on the proces output. The figure-2 depicts feedforward control action.
In case of feedforward control, the effect of disturbance is completely eliminated as it is already sensed and corrected before reaching the process. The feedforward acts beforehand in an anticipatory manner.
Advantages of Feedforward Control System
Following are the advantages of Feedforward control system:
➨Acts before the effect of a disturbance has been felt by the system.
➨It is good for slow system or with significant dead time.
➨It does not introduce instability in the closed loop.
Disadvantages of Feedforward Control System
Following are the disadvantages of Feedforward control system:
➨It requires identification of all possible disturbances and their direct measurement.
➨It can not cope with unmeasured disturbances.
➨It is sensitive to process parameter variations.
➨It requires good knowledge of the process model.
What is difference between or comparison between
Following links mention difference or comparison between various equipments and terms:
comparison between SPI and I2C
difference between PXI and PCI
Microscope vs Telescope
Amplitude Modulation vs Angle Modulation
difference between modem and router
Air Fuel Ratio Sensor vs O2 Sensor
Radiometer vs Spectrometer vs Spectroradiometer
Clamp meter vs digital multimeter
Colorimeter vs Spectrophotometer
difference between Prism and Grating
difference between Venturi meter and Orifice meter
difference between Lux and Lumens