Company Events Academic Community Support Solutions Products & Services Contact NI MyNI

Linearize Subsystem Dialog Box

LabVIEW 2012 Control Design and Simulation Module Help

Edition Date: June 2012

Part Number: 371894G-01

»View Product Info

Requires: Control Design and Simulation Module

Select Tools»Control Design and Simulation»Linearize Subsystem to display this dialog box.

Use this dialog box to trim and/or linearize a simulation subsystem interactively. You can trim and/or linearize only continuous subsystems. Linear models are compatible with the Control Design VIs and functions.

This dialog box includes the following components:

  • Trimmed Operating Point—Displays the names and values of the trimmed states, inputs, outputs, and state derivatives that correspond to any trim constraints you specify. Click the Trim button to calculate these values.

    After you calculate the Trimmed Operating Point, click the Import trimmed values button to use the trimmed operating point as the initial values for the linearize algorithm.
    • States—Displays the names, values, and derivatives of the subsystem states.
    • Inputs—Displays the names and values of the subsystem inputs.
    • Outputs—Displays the names and values of the subsystem outputs.
  • Import trimmed values—Transfers state, input, and output values from the Trimmed Operating Point section to the Initial Inputs, Initial Outputs, and Initial States pages. Click this button after you click the Trim button. Then, click the Linearize button to linearize the subsystem around the trimmed operating point.
  • Subsystem—Use this page to specify the location of the subsystem you want to trim and/or linearize.
    • Location—Use this section to specify whether the subsystem is on disk or in memory.
      • From Disk—Specifies that you want to load a subsystem from disk. Enter a path in the Subsystem location text box.
      • From Memory—Specifies that you want to load a subsystem from memory. Select a subsystem from the Subsystems in memory list.
    • Refresh—Recalculates the Initial Inputs, Initial Outputs, and Initial States of the specified subsystem. Click this button if you change the subsystem while this dialog box is open.
    • Subsystem Location—Specifies the location of a subsystem on disk. Click the Browse button to select a different subsystem. This option is availably only when you select From Disk in the Location section.
    • Subsystems in memory—Lists the simulation subsystems in memory. Select a subsystem to convert from this list. This option is availably only when you select From Memory in the Location section.
  • Initial Inputs—Use this page to view subsystem inputs, specify which inputs are static, specify input constraints, and specify input values.
    • Static—Specifies whether this parameter is static or variable. The linearize algorithm excludes parameters marked Static from the linearized model. You can specify a constant Value for static parameters.
    • Name—Displays the name of this parameter.
    • Dimension—Displays whether this parameter is a scalar or a vector.
    • Constraint—Specifies the type of constraint on this parameter. If you select None, the Value is the initial location from which the trim algorithm begins the search for optimal values. If you select Equal to, the Value is a constraint the trim algorithm attempts to satisfy.
    • Value—Specifies the value of this parameter.
  • Initial Outputs—Use this page to view subsystem outputs, specify which outputs are static, specify output constraints, and specify constrained output values.
    • Static—Specifies whether this parameter is static or variable. The linearize algorithm excludes parameters marked Static from the linearized model. You can specify a constant Value for static parameters.
    • Name—Displays the name of this parameter.
    • Dimension—Displays whether this parameter is a scalar or a vector.
    • Constraint—Specifies the type of constraint on this parameter. If you select None, the Value is the initial location from which the trim algorithm begins the search for optimal values. If you select Equal to, the Value is a constraint the trim algorithm attempts to satisfy.
    • Value—Specifies the value of this parameter.
  • Initial States—Use this page to view subsystem states, specify state constraints and state derivative constraints, and specify state values and state derivative values.
    Note  You cannot mark a subsystem state as Static because the linearize algorithm includes all subsystem states in the linearized model.
    • Name—Displays the name of this parameter.
    • Dimension—Displays whether this parameter is a scalar or a vector.
    • State Constraint—Specifies the type of constraint on this parameter. If you select None, the State Value is the initial location from which the trim algorithm begins the search for optimal values. If you select Equal to, the State Value is a constraint the trim algorithm attempts to satisfy.
    • State Value—Specifies the value of this parameter.
    • Derivative Constraint—Specifies the type of constraint on this parameter. If you select None, the Derivative Value is the initial location from which the trim algorithm begins the search for optimal values. If you select Equal to, the Derivative Value is a constraint the trim algorithm attempts to satisfy.
    • Derivative Value—Specifies the value of this parameter.
  • Trim—Click this button to trim the subsystem. The trim algorithm calculates the Trimmed Operating Point using the states, inputs, outputs, and state derivatives for which you specified a Constraint of Equal to.

    After you trim a subsystem, click the Import trimmed values button to use these trimmed values as the operating point for the linearize algorithm.
  • Linearize—Click this button to convert the subsystem into a linear time-invariant (LTI) state-space model. After you click this button, the LabVIEW Control Design and Simulation Module launches the SIM Linearizer Results dialog box. This dialog box includes the following components:
    • Copy—Copies the model information to the clipboard. You then can paste the model as a block diagram constant, as a front panel control, or into the configuration dialog box of a State-Space function.
    • Save Subsystem—Saves the LTI model as a VI.
    • Save Model—Saves the LTI model as a file with any extension. You then can load this file into a controller by using the CD Read Model from File VI.

This dialog box uses the Trim & Linearize VIs to trim and linearize a subsystem. You can linearize a subsystem programmatically using the SIM Linearize VI. You can trim a subsystem programmatically using the SIM Trim VI.


 

Your Feedback! poor Poor  |  Excellent excellent   Yes No
 Document Quality? 
 Answered Your Question? 
Add Comments 1 2 3 4 5 submit