11. Linearizing a Subsystem (Control Design and Simulation Module)

To perform analysis on a simulation model, you first must create a linearized subsystem. Linearizing a nonlinear simulation subsystem involves approximating the behavior of that subsystem around an operating point. Complete the following steps to linearize a subsystem using the Linearize Subsystem dialog box and perform analysis on the linearized subsystem.

1. Click and drag a selection rectangle around the portion of the simulation diagram selected in the following simulation diagram.

   

2. Select Edit»Create Simulation Subsystem.
3. Save the VI. When LabVIEW prompts you to save, click the Yes button to save the new, unsaved subsystem. Name the subsystem Spring Mass Subsystem.vi.
4. Right-click the subsystem and select Trim/Linearize Subsystem from the shortcut menu. The Linearize Subsystem dialog box appears.
5. In the Static column of the Initial Inputs tab, place checkmarks in the checkboxes next to Stiffness and Mass. During the linearization process, these become constants instead of variables.
6. In the Value column of the Initial Inputs tab, enter a value of 100 for Stiffness, a value of 10 for Mass, and a value of -9.8 for Force.
7. Click the Linearize button to open the SIM Linearizer Results dialog box and display an equation representing the transfer function of the model.
8. Click the Save Model button and name the file Linearized Spring-Mass Damper Example.lti.
9. Close all open dialog boxes.
10. Save the VI.