Feedback from the Sensors is Compared to the Expectancies in the Comparator.
Expectancies of what is to be accomplished by the movement is set up in the Comparator, which is probably a number of locations in the brain--such as the frontal lobe, the cerebellum, and the brainstem to mention a few.
If the feedback from the Sensors does not match the expectancies, error messages are sent to the Mixer to correct the movement and to the Governor so that we are aware of the process.
NOTES: Here is an interesting note on Feedback.