SI Create Partially Known Continuous Transfer Function Model VI

Owning Palette: Partially Known Model Estimation VIs

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

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.

Details  Examples

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 node runs. This input provides standard error in functionality.
	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. This output provides standard error out functionality.

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 node runs. This input provides standard error in functionality.
	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. This output provides standard error out functionality.

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 node runs. This input provides standard error in functionality.
	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. This output provides standard error out functionality.

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:

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