operation. This arises because of the integral element in the controller
which bases its error on the duration of the error signal input to the
controller and does not take account of any manually introduced signals.
Thus, changing the manually introduced signal can lead to the output
from the controller in the automatic mode not being the same as that in
the manual mode. To avoid this 'bump' and give a bumpless transfer,
modem controllers automatically adjust the contribution to the control
law from the integral element.