[Music]
welcome to the derivative control mode
analogy the derivative function of a PID
controller is to shorten the time
duration of an operation to illustrate
this function consider a boat that
travels from a launching dock on one
side of a lake to a dock on the opposite
shore the boat starts slowly from a
stationary position and eventually picks
up speed as the boat approaches its
destination it must slow down so that it
doesn't slam into the dock and go up the
shore
if it were possible to speed up the
acceleration of the boat and approach
the opposite shore as closely as
possible at full speed before
decelerating it would take less time to
make the trip
improving acceleration and deceleration
is the advantage of the derivative
control mode
let's say the red boat has one motor and
the green boat has two motors the second
motor on the green boat can provide
power in both forward and reverse
directions when the boats leave the
launching dock the green boat
accelerates faster because it receives
extra power from its second motor
when the red boat reaches its full speed
the second motor of the green boat is
disabled at this point the boats are
traveling at the same speed
when the red boat approaches the shore
it must decelerate slowly so that it
doesn't slam into the dock when the
green boat nears the shore it can
approach it at full speed because its
second engine is reactivated in the
reverse direction causing a rapid
deceleration
the second motor provides a boosting and
a braking action the derivative control
mode in an industrial application such
as the movement of a robotic arm from
one position to another quickly works
the same way
the derivative operation is a function
of the controller that initiates the
movement of the robot
now let's check your understanding
please pause the video if you need more
time to answer the questions
question one
the D in the term PID control refers to
derivative
question two
the derivative control mode provides
both acceleration and braking action
question three
the derivative action of a PID
controller shortens the duration of an
operation congratulations you have
completed this learning object
derivative control mode analogy
