1, different proportions

Negative feedback is the control mechanism in most cases and positive feedback is the control mechanism in a few cases.

2. Different definitions

Negative feedback: the feedback information sent by the controlled part adjusts the activities of the controlled part, and finally makes the activities of the controlled part change in the opposite direction to its original activities; Feedback refers to the process that the output of the system returns to the input end and changes the input in some way, thus affecting the system function.

Positive feedback The feedback information sent by the controlled part promotes and strengthens the activities of the controlled part, and finally changes the activities of the controlled part to its original direction; The polarity of the feedback signal is the same as the polarity of the system input signal, which plays a role in enhancing the net input signal of the system, and is called positive feedback mode.

3. Different functions

Negative feedback: plays the role of correcting and weakening control information; Make the output play the opposite role to the input, reduce the error between the system output and the system target, and the system tends to be stable. Positive feedback plays a role in strengthening control information; Make the output play the role of similar input, make the system deviation increase continuously, make the system oscillate and amplify the control function.