CD Continuous Observer Function

Simulation VI and Function

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CD Continuous Observer Function

Owning Palette: Continuous Linear Systems Functions

Installed With: Control Design and Simulation Module

Implements an observer for a continuous linear time-invariant (LTI) state-space model.

Refer to Chapter 15, Estimating Model States, of the LabVIEW Control Design User Manual for information about using a continuous observer.

Details

Dialog Box Options

Block Diagram Inputs

Block Diagram Outputs

Place on the block diagram

Find on the Functions palette

Dialog Box Options

Parameter

Description

Parameters

Lists all the parameters associated with this function. Select a parameter from this list to configure the parameter. When you select a parameter, the parameter and its associated Parameter source control appear in the Parameter Information section of the configuration dialog box.

Preview

Displays a graphical preview, if available, of the function output or configuration.

Parameter Information

Contains the parameters you can configure for this function. You must select a parameter from the Parameters list to make that parameter and its associated Parameter source control visible in the Parameter Information section of the configuration dialog box.

Parameter source

Specifies whether you configure this parameter using the Configuration Dialog Box or a Terminal on the simulation diagram. The default value is Configuration Dialog Box. If you select Terminal, LabVIEW displays an input for that parameter on the simulation diagram, and you can wire values to that input to configure this function programmatically. If you select Configuration Dialog Box, LabVIEW removes that input from the simulation diagram. You then must set the value for this parameter inside the configuration dialog box.

State-Space Model

Specifies the mathematical representation of and information about the system for which this function implements the observer.

Model name—Specifies the name of the state-space model.

Sampling Time—Specifies the sampling time of the system model and determines whether the model represents a continuous-time or discrete-time system. If the model represents a continuous-time system, Sampling Time must equal zero. If the model represents a discrete-time system, Sampling Time must be greater than zero and equal to the sampling rate, in seconds, of the discrete system. The default is 0.

Note If you use the inputs to create a continuous-time system, setting the Sampling Time to a value greater than zero does not yield the discrete-time equivalent of the system. You must use the CD Convert Continuous Stochastic to Discrete VI to convert the continuous-time system to the discrete-time equivalent of the system.

A—Specifies the n × n state matrix of the given system.
B—Specifies the n × m input matrix of the given system.
C—Specifies the r × n output matrix of the given system.
D—Specifies the r × m direct transmission matrix of the given system.

where m is the number of inputs
n is the number of states
r is the number of outputs

Observer Gain

Specifies the estimator gain matrix this function applies to the difference between the observed output and the estimated output, which is y(t) – yhat(t). You can use the CD Pole Placement VI or the CD Ackermann VI to calculate Observer Gain.

Initial state estimate xhat(t0)

Specifies the initial states from which this function begins estimating the model states. If you do not specify a value for this parameter, Initial state estimate xhat(t0) is a vector of zeros.

Output y(t)

Specifies the measurements made on the State-Space Model.

Input u(t)

Specifies the control action this function applies to the model. If you specify a vector of zeros for Input u(t), this function does not apply any control action.

Block Diagram Inputs

Parameter	Description
Observer Gain	Specifies the estimator gain matrix this function applies to the difference between the observed output and the estimated output, which is y(t) – yhat(t). You can use the CD Pole Placement VI or the CD Ackermann VI to calculate Observer Gain.
Initial state estimate xhat(t0)	Specifies the initial states from which this function begins estimating the model states. If you do not specify a value for this parameter, Initial state estimate xhat(t0) is a vector of zeros.
Output y(t)	Specifies the measurements made on the State-Space Model.
Input u(t)	Specifies the control action this function applies to the model. If you specify a vector of zeros for Input u(t), this function does not apply any control action.
State-Space Model	Specifies the mathematical representation of and information about the system for which this function calculates the estimated states.

Block Diagram Outputs

Parameter	Description
Estimated Output yhat(t)	Returns the estimated model output at time t.
Estimated State xhat(t)	Returns the estimated model states at time t.

CD Continuous Observer Details

This function solves the following equations:

The output Estimated State xhat(t) is the result of integrating by using the ordinary differential equation (ODE) solver and time step information you specify for the Simulation Loop.

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