SI Create Partially Known Continuous Transfer Function Model VI

System Identification VIs

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SI Create Partially Known Continuous Transfer Function Model VI

Owning Palette: Partially Known Model Estimation VIs

Installed With: System Identification Toolkit

Creates a continuous transfer function model for a partially known system. Use the SI Estimate Partially Known Continuous Transfer Function Model VI to estimate the model you create with this VI. You must manually select the polymorphic instance to use.

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Use the pull-down menu to select an instance of this VI.

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SI Create Partially Known Continuous Transfer Function Model (1st Order)

delay (s) specifies the delay, in seconds, of the continuous transfer function model.
delay initial guess specifies the initial guess of the system delay. The value of delay initial guess must be greater than or equal to 0.
delay upper limit specifies the upper limit to use to search for the optimal delay of the model. The value of delay upper limit must be greater than 0. The default is Inf.
delay lower limit specifies the lower limit to use to search for the optimal delay of the model. The value of delay lower limit must be greater than 0 and smaller than the delay upper limit. The default is 0.
static gain specifies the static gain of the continuous transfer function model.
static gain initial guess specifies the initial guess of the static gain.
static gain upper limit specifies the upper limit to use to search the optimal static gain of the model. The default is Inf.
static gain lower limit specifies the lower limit to use to search for the optimal static gain of the model. The default is -Inf.
Tp (s) specifies the time constant, in seconds, of the continuous transfer function model.
Tp initial guess specifies the initial guess of the system time constant. The value of Tp initial guess must be greater than or equal to 0.
Tp upper limit specifies the upper limit to use to search for the optimal time constant of the model. The value of Tp upper limit must be greater than 0. The default is Inf.
Tp lower limit specifies the lower limit to use to search for the optimal time constant of the model. The value of Tp lower limit must be greater than or equal to 0. The default is 0.
error in describes error conditions that occur before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node.
status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE.
code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.
system model out contains information of the mathematical model of a partially known system. The information includes model type, model orders, constraints on each model coefficient, input and output names of the system, and so on.
error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error.
status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.
code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.

SI Create Partially Known Continuous Transfer Function Model (2nd Order)

delay (s) specifies the delay, in seconds, of the continuous transfer function model.
delay initial guess specifies the initial guess of the system delay. The value of delay initial guess must be greater than or equal to 0.
delay upper limit specifies the upper limit to use to search for the optimal delay of the model. The value of delay upper limit must be greater than 0. The default is Inf.
delay lower limit specifies the lower limit to use to search for the optimal delay of the model. The value of delay lower limit must be greater than 0 and smaller than the delay upper limit. The default is 0.
static gain specifies the static gain of the continuous transfer function model.
static gain initial guess specifies the initial guess of the static gain.
static gain upper limit specifies the upper limit to use to search the optimal static gain of the model. The default is Inf.
static gain lower limit specifies the lower limit to use to search for the optimal static gain of the model. The default is -Inf.
natural freq (rad/s) specifies the natural frequency, in radians per second, of the continuous transfer function model.
freq initial guess specifies the initial guess of the system natural frequency. freq initial guess must be greater than or equal to 0.
freq upper limit specifies the upper limit to use to search for the optimal natural frequency of the model. The value of freq upper limit must be greater than 0. The default is Inf.
freq lower limit specifies the lower limit to use to search for the optimal natural frequency of the model. The value must be greater than or equal to 0. The default is 0.
damping ratio specifies the damping ratio of the continuous transfer function model.
ratio initial guess specifies the initial guess of the damping ratio. ratio initial guess must be greater than or equal to 0.
ratio upper limit specifies the upper limit to use to search for the optimal damping ratio of the model. The value of ratio upper limit must be greater than 0. The default is Inf.
ratio lower limit specifies the lower limit to use to search for the optimal damping ratio of the model. The value of ratio lower limit must be greater than or equal to 0. The default is 0.
error in describes error conditions that occur before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node.
status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE.
code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.
system model out contains information of the mathematical model of a partially known system. The information includes model type, model orders, constraints on each model coefficient, input and output names of the system, and so on.
error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error.
status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.
code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.

SI Create Partially Known Continuous Transfer Function Model (General)

delay (s) specifies the delay, in seconds, of the continuous transfer function model.
delay initial guess specifies the initial guess of the system delay. The value of delay initial guess must be greater than or equal to 0.
delay upper limit specifies the upper limit to use to search for the optimal delay of the model. The value of delay upper limit must be greater than 0. The default is Inf.
delay lower limit specifies the lower limit to use to search for the optimal delay of the model. The value of delay lower limit must be greater than 0 and smaller than the delay upper limit. The default is 0.
orders of transfer function model specifies the numerator and denominator orders of the transfer function model.
num order specifies the numerator order of the system model. The default value is 1.
den order specifies the denominator order of the system model. The default value is 2. The value of den order must be greater than the value of num order.
static gain specifies the static gain of the continuous transfer function model.
static gain initial guess specifies the initial guess of the static gain.
static gain upper limit specifies the upper limit to use to search the optimal static gain of the model. The default is Inf.
static gain lower limit specifies the lower limit to use to search for the optimal static gain of the model. The default is -Inf.
# of zeros/poles at origin specifies the number of zeros or poles at the origin. You can specify the number of either zeros or poles, but you cannot have both zeros and poles at the origin.
zeros/poles specifies the zeros or poles of the system.
number specifies the number of zeros or poles at the origin.
error in describes error conditions that occur before this VI or function runs. The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node.
status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE.
code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.
Tp (s) specifies the time constant(s), in seconds, of the continuous transfer function model.
Tp initial guess specifies the initial guess of the system time constant. The value of Tp initial guess must be greater than or equal to 0.
Tp upper limit specifies the upper limit to use to search for the optimal time constant of the model. The value of Tp upper limit must be greater than 0. The default is Inf.
Tp lower limit specifies the lower limit to use to search for the optimal time constant of the model. The value of Tp lower limit must be greater than or equal to 0. The default is 0.
natural freq (rad/s) & damping ratio specifies the natural frequency(s) and the damping ratio(s) of the continuous transfer function model.
freq initial guess specifies the initial guess of the system natural frequency. freq initial guess must be greater than or equal to 0.
freq upper limit specifies the upper limit to use to search for the optimal natural frequency of the model. The value of freq upper limit must be greater than 0. The default is Inf.
freq lower limit specifies the lower limit to use to search for the optimal natural frequency of the model. The value must be greater than or equal to 0. The default is 0.
ratio initial guess specifies the initial guess of the damping ratio. ratio initial guess must be greater than or equal to 0.
ratio upper limit specifies the upper limit to use to search for the optimal damping ratio of the model. The value of ratio upper limit must be greater than 0. The default is Inf.
ratio lower limit specifies the lower limit to use to search for the optimal damping ratio of the model. The value of ratio lower limit must be greater than or equal to 0. The default is 0.
system model out contains information of the mathematical model of a partially known system. The information includes model type, model orders, constraints on each model coefficient, input and output names of the system, and so on.
error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error.
status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.
code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.

SI Create Partially Known Continuous Transfer Function Model Details

The following equations represent first-order, second-order, and general models, respectively.

First-order models:

Second-order models:

General models:

whereK is the transfer function gain
Td is the delay
Tp is the first-order time constant
r is the damping ratio
w is the natural frequency

If a system has zeros at the origin, you can use general models to represent the system using the following equation:

You must select the zeros input of the # of zeros/poles at origin parameter and specify the number of zeros in the number input.

If a system has poles at the origin, you can use general models to represent the system using the following equation:

You must select the poles input of the # of zeros/poles at origin parameter and specify the number of poles in the number input.

Examples

Refer to the following VIs for examples of using the SI Create Partially Known Continuous Transfer Function Model VI:

  • Continuous Transfer Function Model of a DC Motor with Known Gain VI: labview\examples\System Identification\Getting Started\Grey-Box Model.llb

     Open example  Browse related examples

  • Ball and Beam VI: labview\examples\System Identification\Industry Applications\Mechanical Systems.llb

     Open example  Browse related examples

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