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12. Performing Analysis on a Linearized Subsystem (Control Design and Simulation Module)

LabVIEW 2012 Control Design and Simulation Module Help

Edition Date: June 2012

Part Number: 371894G-01

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After you linearize a subsystem, you might want to perform analysis on that subsystem by applying an impulse response and testing the reaction of the system. This procedure explains how to use LabVIEW Control Design and Simulation VIs to determine the damping ratio and the natural frequency of the newly linearized subsystem, view the mathematical representation of the transfer function equation, and display a pole-zero map of the results. You can use these results to determine how the linearized system performs under different impulse response conditions.

  1. Create a new blank VI.
  2. If you are not already viewing the Functions palette, select View»Functions Palette to display this palette.
  3. Select Control Design & Simulation»Control Design»Model Construction to display the Model Construction palette.
  4. Add the CD Read Model from File VI to the block diagram.
  5. Right-click the File Path input of the CD Read Model from File VI and select Create»Control from the shortcut menu. Enter the path to the Linearized Spring-Mass Damper Example.lti model in the File Path control.
  6. Add the CD Draw Transfer Function Equation VI to the block diagram. Wire the First State-Space Model in Record output of the CD Read Model From File VI to the Transfer-Function Model input of the CD Draw Transfer Function Equation VI.
    Note  Because the CD Draw Transfer Function Equation VI is a polymorphic VI, the Transfer-Function Model input changes to a State-Space Model input when you wire these functions together.
  7. Right-click the Equation output of the CD Draw Transfer Function VI and select Create»Indicator from the shortcut menu.
  8. View the front panel and run the VI. Note that the Equation indicator displays the mathematical representation of the transfer function of the model you created.
  9. Use the palette search to add a CD Pole-Zero Map VI, a CD Damping Ratio and Natural Frequency VI, and a CD Impulse Response VI to the block diagram.
    Note  You also can perform step impulse analysis on a linearized subsystem using the CD Step Response VI.
  10. Wire the First State-Space Model in Record output of the CD Read Model from File VI to the State-Space Model input of each VI.
  11. Create indicators for the Pole-Zero Map output of the CD Pole-Zero Map VI, the Damping Ratio and Natural Frequencies outputs of the CD Damping Ratio and Natural Frequency VI, and the Impulse Response Graph output of the CD Impulse Response VI. The block diagram now resembles the following diagram.

  12. Switch to the front panel and run the VI. The front panel now resembles the following front panel.

Note that the Impulse Response Graph displays a waveform identical to the waveform in the Spring-Mass Damper Example.vi. The Impulse Response Graph simulates the original model.

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