Experiment No.5The objective of this practice is to carry out a closed loop control by an on/off controller by the closing and opening of the A VS-I, AVS-2, AVS-3 solenoid valves and the activation of pump 2 using proportional derivative controller.

Apparatus: UCP-L Control and Acquisition Software Water

Diagram:

Procedure: Connect the interface of the equipment and the control software Select the control on/off option Make a double click on the on/off control, select the flow wanted. there are a certain flow, a

tolerance and a performance time set by default. It allows the students to play with these parameters and see the influences of each one

The level control can be carried out by the activation of a single actuator, or of several ones, to which different tolerances are allowed. These controllers work as security system measures when the controlled variable exceeds in a tolerance the set value. To activate or to disable any of these controllers you may have to double click on each of them and press the button "PAUSE"

Calculate the inertia of the system for an on/off response and determine the limit time for an exact control

The following graph is obtained when we set the gain upto 0.005

D controllersD controllers generate the manipulated variable from the rate of change of the error and not as P controllers from their amplitude. Therefore, they react much faster than P controllers: even if the error is small, derivative controllers generate. By anticipation, so to speak large control amplitudes as soon as a change in amplitude occurs. A steady-state error signal, however, is not recognized by D controllers, because regardless of how big the error, its rate of change is zero. Therefore, derivative-only controllers are rarely used in practice. They are usually found in combination with other control elements, mostly in combination with proportional control.

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PD controller graph

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Time

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