SI Estimate ARX Model VI

Owning Palette: Parametric Model Estimation VIs

Requires: Advanced Signal Processing Toolkit or Control Design and Simulation Module

Estimates the parameters of an ARX model for an unknown system. Wire data to the stimulus signal and response signal inputs to determine the polymorphic instance to use or manually select the instance.

The success of the model estimation depends on the correct selection of the orders of ARX model input. Use the SI Estimate Orders of System Model VI to estimate orders of ARX model if you do not know the orders of the model.

Example

SI Estimate ARX Model (SISO Waveform)

	stimulus signal specifies the input waveform of the stimulus signal.
	response signal specifies the input waveform of the response signal. The length of response signal must be greater than [max(A order, B order + delay – 1) + (A order + B order)].
	orders of ARX model specifies the orders and delay of the ARX model. A order specifies the order of the A coefficients of the system model. The value of A order must be greater than or equal to 0. B order specifies the order of the B coefficients of the system model. The value of B order must be greater than or equal to 1. delay specifies the delay k of the system model. The value of delay must be greater than or equal to 0.
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	system model out returns information about the model structure, nominal or estimated parameters, identification result, and so on. Use the Model Management VIs to retrieve the information system model out contains. Note  You can use a customized system model probe to view model information that flows through system model wires when you debug a block diagram created with the System Identification VIs. Right-click a system model wire and select Custom Probe»SI System Model from the shortcut menu to use the system model probe.
	coefficients of ARX model returns the coefficients of the ARX model. A returns the A coefficients of the system model. B returns the B coefficients of the system model.
	noise returns the disturbance e(t) in the estimated system model.
	error out contains error information. This output provides standard error out functionality.

SI Estimate ARX Model (SISO Array)

	stimulus signal specifies an array that represents the stimulus signal.
	response signal specifies an array that represents the response signal. The length of response signal must be greater than [max(A order, B order + delay – 1) + (A order + B order)].
	orders of ARX model specifies the orders and delay of the ARX model. A order specifies the order of the A coefficients of the system model. The value of A order must be greater than or equal to 0. B order specifies the order of the B coefficients of the system model. The value of B order must be greater than or equal to 1. delay specifies the delay k of the system model. The value of delay must be greater than or equal to 0.
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	sampling rate (Hz) specifies the sampling frequency in hertz. The value of sampling rate must be greater than 0. The default is 1.
	system model out returns information about the model structure, nominal or estimated parameters, identification result, and so on. Use the Model Management VIs to retrieve the information system model out contains. Note  You can use a customized system model probe to view model information that flows through system model wires when you debug a block diagram created with the System Identification VIs. Right-click a system model wire and select Custom Probe»SI System Model from the shortcut menu to use the system model probe.
	coefficients of ARX model returns the coefficients of the ARX model. A returns the A coefficients of the system model. B returns the B coefficients of the system model.
	noise returns the disturbance e(t) in the estimated system model.
	error out contains error information. This output provides standard error out functionality.

SI Estimate ARX Model (MISO Waveform)

	stimulus signals specifies the input waveform array of the stimulus signals. Each element of the array is the waveform of one stimulus signal.
	response signal specifies the input waveform of the response signal. The length of response signal must be greater than [max(A order, max(B orders + delays) – 1) + (A order + sum(B orders))].
	orders of ARX model specifies the orders and delays of the ARX model. A order specifies the order of the A coefficients of the system model. The value of A order must be greater than or equal to 0. B orders specifies the orders of the B coefficients of the system model. The value of B orders must be greater than or equal to 1. delays specifies the delays k of the model. The value of delays must be greater than or equal to 0.
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	system model out returns information about the model structure, nominal or estimated parameters, identification result, and so on. Use the Model Management VIs to retrieve the information system model out contains. Note  You can use a customized system model probe to view model information that flows through system model wires when you debug a block diagram created with the System Identification VIs. Right-click a system model wire and select Custom Probe»SI System Model from the shortcut menu to use the system model probe.
	coefficients of ARX model returns the coefficients of the ARX model. A returns the A coefficients of the system model. B returns the B coefficients of the system model.
	noise returns the disturbance e(t) in the estimated system model.
	error out contains error information. This output provides standard error out functionality.

SI Estimate ARX Model (MISO Array)

	stimulus signals specifies an array that represents the stimulus signals. Each row in the array is one stimulus signal.
	response signal specifies an array that represents the response signal. The length of response signal must be greater than [max(A order, max(B orders + delays) – 1) + (A order + sum(B orders))].
	orders of ARX model specifies the orders and delays of the ARX model. A order specifies the order of the A coefficients of the system model. The value of A order must be greater than or equal to 0. B orders specifies the orders of the B coefficients of the system model. The value of B orders must be greater than or equal to 1. delays specifies the delays k of the model. The value of delays must be greater than or equal to 0.
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	sampling rate (Hz) specifies the sampling frequency in hertz. The value of sampling rate must be greater than 0. The default is 1.
	system model out returns information about the model structure, nominal or estimated parameters, identification result, and so on. Use the Model Management VIs to retrieve the information system model out contains. Note  You can use a customized system model probe to view model information that flows through system model wires when you debug a block diagram created with the System Identification VIs. Right-click a system model wire and select Custom Probe»SI System Model from the shortcut menu to use the system model probe.
	coefficients of ARX model returns the coefficients of the ARX model. A returns the A coefficients of the system model. B returns the B coefficients of the system model.
	noise returns the disturbance e(t) in the estimated system model.
	error out contains error information. This output provides standard error out functionality.

SI Estimate ARX Model (MIMO Waveform)

	stimulus signals specifies the input waveform array of the stimulus signals. Each element of the array is the waveform of one stimulus signal.
	response signals specifies the input waveform array of the response signals. Each element of the waveform array is the waveform of one response signal. The length of response signals must be greater than [max(max(A orders) * number of outputs, max(B orders + delays) * number of inputs – 1) + max(A orders) * number of outputs + max(B orders + delays) * number of inputs].
	orders of ARX model specifies the orders and delay of the ARX model. A orders specifies the order of the A coefficients of the model. The value of A orders must be greater than or equal to 0. B orders specifies the orders of the B coefficients of the system model. The value of B orders must be greater than or equal to 1. delays specifies the delays k of the model. The value of delays must be greater than or equal to 0.
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	system model out returns information about the model structure, nominal or estimated parameters, identification result, and so on. Use the Model Management VIs to retrieve the information system model out contains. Note  You can use a customized system model probe to view model information that flows through system model wires when you debug a block diagram created with the System Identification VIs. Right-click a system model wire and select Custom Probe»SI System Model from the shortcut menu to use the system model probe.
	coefficients of ARX model returns the coefficients of the ARX model. A returns the A coefficients of the system model. B returns the B coefficients of the system model.
	noises returns the disturbances e(t) in the estimated system model.
	error out contains error information. This output provides standard error out functionality.

SI Estimate ARX Model (MIMO Array)

	stimulus signals specifies an array that represents the stimulus signals. Each row in the array is one stimulus signal.
	response signals specifies an array that represents the response signals. Each row in the array is one response signal. The length of response signals must be greater than [max(max(A orders) * number of outputs, max(B orders + delays) * number of inputs – 1) + max(A orders) * number of outputs + max(B orders + delays) * number of inputs].
	orders of ARX model specifies the orders and delay of the ARX model. A orders specifies the order of the A coefficients of the model. The value of A orders must be greater than or equal to 0. B orders specifies the orders of the B coefficients of the system model. The value of B orders must be greater than or equal to 1. delays specifies the delays k of the model. The value of delays must be greater than or equal to 0.
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	sampling rate (Hz) specifies the sampling frequency in hertz. The value of sampling rate must be greater than 0. The default is 1.
	system model out returns information about the model structure, nominal or estimated parameters, identification result, and so on. Use the Model Management VIs to retrieve the information system model out contains. Note  You can use a customized system model probe to view model information that flows through system model wires when you debug a block diagram created with the System Identification VIs. Right-click a system model wire and select Custom Probe»SI System Model from the shortcut menu to use the system model probe.
	coefficients of ARX model returns the coefficients of the ARX model. A returns the A coefficients of the system model. B returns the B coefficients of the system model.
	noises returns the disturbances e(t) in the estimated system model.
	error out contains error information. This output provides standard error out functionality.

Example

Refer to the Estimate Polynomial Models VI in the labview\examples\System Identification\Getting Started\Parametric Estimation.llb for an example of using the SI Estimate ARX Model VI.