 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 1. The D in the term PID control refers to derivative. Question 2. The derivative control mode provides both acceleration and braking action. Question 3. The derivative action of a PID controller shortens the duration of an operation. Congratulations! You have completed this learning object, derivative control mode analogy.