Virtual PID Experiments Using LabVIEW

In class of Automatic Control, students learn a lot of tools like root locus and Bode plot to analyze the plant under study. However, even with the aid of software simulation like MATLAB, students who first reach this subject usually wonder how simple control scheme like PID is implemented when it comes to real-world applications. PID control, though pretty fundamental, plays an important rule in industrial applications. When reaching such topic, professors usually asks those who are interested in this to build a circuit like Fig. 1 to get some insights.

Fig. 1 PID positioning control circuit

The idea of this lecturing project was to make the control implementation process more intuitive. To achieve this goal virtual PID experiments were first built in LabVIEW environment with block diagrams, and then students could manually adjust the desired drive signal and control parameters (see Fig. 2). Via observation on the waveform chart of command signal and system output, students could easily understand how real-time feedback control works and effects of control parameters on computer screen (see Fig. 3).

Fig. 2 Construction of PID controller in LabVIEW environment 

Fig. 3 Virtual PID experiments using LabVIEW interface

The final step was to wire the controller built to the plant, motor in this case, via physical devices like DAQ of National Instruments. Students were allowed to tune system performance on the screen without constructing a physical PID controller, which was laborious and less easily tuned up.