feedback

1. POSITIVE AND NEGATIVE
FEEDBACK

2. FEEDBACK
MECHANISMS

3. WHAT IS FEEDBACK?
Feedback is the process in which part of the
output of a system is returned to its input in
order to regulate its further output.

4. NEGATIVE FEEDBACK
 Have you ever been scolded for not cleaning your room?
 Cleaning your room is how you respond to being scolded.
 A negative feedback system involves the detection of an
undesirable condition and the response to make that
condition ideal.
Negative Feedback
+
_

5. NEGATIVE FEEDBACK
Basic structure:
INPUT DETECTION RESPONSE OUTPUT SHUT OFF

6. NEGATIVE FEEDBACK
 Negative feedback occurs when the output
of a system acts to oppose changes to the
input of the system
 A thermostat is an example of a negative
feedback system

7. A thermostat is a device for regulating the temperature of a system so that the
system's temperature is maintained near a desired setpoint temperature.
Room temp is
below the
setpoint
Room temp is
above the
setpoint
Room temp
increases
Room temp
decreases
Set point
is reached
Set point
is reached
THERMOSTAT

8. POSITIVE FEEDBACK
 A positive feedback loop occurs when the output
of a system acts to enhance the changes to the
input of the system.
 Acts to increase the magnitude of response or
disturbance
 Often referred to as a viscous cycle or runaway
 Amplification

9. POSITIVE FEEDBACK

10. OTHER KINDS OF
FEEDBACK
Feed-forward
 Not technically
feedback, but similar.
 The system responds
in anticipation of a
change