You are here: NI Home > Support > Product Reference > Manuals > LabVIEW Control Design Toolkit 3.0 Help

Plots the Evans plot or trajectory of closed-loop poles of a single-input single-output (SISO) system as the feedback gain varies from zero to infinity. You can display this data in the CD Root Locus Plot indicator. You can use this polymorphic to plot the root-locus plot of state-space, transfer function, and zero-pole-gain models. The data type you wire to the State-Space Model input determines the polymorphic instance to use.

Details  

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

Select an instance CD Root Locus with Gain (State-Space)CD Root Locus with Gain (Transfer Function)CD Root Locus with Gain (Zero-Pole-Gain)

CD Root Locus with Gain (State-Space)

	Root Locus Graph Reference specifies a reference to the Root Locus Graph.
	State-Space Model contains a mathematical representation of and information about the system for which this VI generates the root locus, or Evans, plot.
	Gain Info specifies the initial and final gain values. K0 is the initial feedback gain value. The default is 0. Kf is the final feedback gain value. The default is 0.
	Gain specifies the feedback gain to apply to each open-loop model pole. Use this parameter to determine the feedback gain necessary to place an open-loop pole in a particular location. Each element of the Gain parameter corresponds to a different open-loop pole.
	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.
	Feedback specifies the type of feedback, positive or negative. 0 negative (default)—The closed-loop system has negative feedback. 1 positive—The closed-loop system has positive feedback.
	Minimum Number of Points specifies the minimum number of points this VI uses for the root locus plot. The default is 300 points.
	Root Locus Graph displays the Evans plot of a SISO feedback system on an XY graph. Right-click this terminal on the block diagram and select Create»Indicator from the shortcut menu to display this data in the CD Root Locus Plot indicator.
	Root Locus Data returns information about the root locus calculation. K is a 1D-array of m elements of all the gain values that this VI uses to create the root locus. Roots is an m x n array, where n is the number of poles in the closed-loop transfer function. The ith row of Roots consists of the n closed-loop poles that result when the feedback gain has value equal to the ith element of K.
	Root Locus Information returns information about the root locus plot, such as the bifurcation points and open-loop poles and zeros. Open-Loop Zeros returns the zeros of the open-loop system and the location of the closed-loop poles when the gain K equals infinity. Open-Loop Poles returns the poles of the closed-loop system when the gain K equals 0. Bifurcation Points returns the points in the root locus plot where a pair of real poles splits into a conjugate pair of poles. K at Bifurcation Point returns the gain values at which the bifurcation occurs in the root locus plot.
	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.

CD Root Locus with Gain (Transfer Function)

	Root Locus Graph Reference specifies a reference to the Root Locus Graph.
	Transfer Function Model contains a mathematical representation of and information about the system for which this VI generates the root locus, or Evans, plot.
	Gain Info specifies the initial and final gain values. K0 is the initial feedback gain value. The default is 0. Kf is the final feedback gain value. The default is 0.
	Gain specifies the feedback gain to apply to each open-loop model pole. Use this parameter to determine the feedback gain necessary to place an open-loop pole in a particular location. Each element of the Gain parameter corresponds to a different open-loop pole.
	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.
	Feedback specifies the type of feedback, positive or negative. 0 negative (default)—The closed-loop system has negative feedback. 1 positive—The closed-loop system has positive feedback.
	Minimum Number of Points specifies the minimum number of points this VI uses for the root locus plot. The default is 300 points.
	Root Locus Graph displays the Evans plot of a SISO feedback system on an XY graph. Right-click this terminal on the block diagram and select Create»Indicator from the shortcut menu to display this data in the CD Root Locus Plot indicator.
	Root Locus Data returns information about the root locus calculation. K is a 1D-array of m elements of all the gain values that this VI uses to create the root locus. Roots is an m x n array, where n is the number of poles in the closed-loop transfer function. The ith row of Roots consists of the n closed-loop poles that result when the feedback gain has value equal to the ith element of K.
	Root Locus Information returns information about the root locus plot, such as the bifurcation points and open-loop poles and zeros. Open-Loop Zeros returns the zeros of the open-loop system and the location of the closed-loop poles when the gain K equals infinity. Open-Loop Poles returns the poles of the closed-loop system when the gain K equals 0. Bifurcation Points returns the points in the root locus plot where a pair of real poles splits into a conjugate pair of poles. K at Bifurcation Point returns the gain values at which the bifurcation occurs in the root locus plot.
	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.

CD Root Locus with Gain (Zero-Pole-Gain)

	Root Locus Graph Reference specifies a reference to the Root Locus Graph.
	Zero-Pole-Gain Model contains a mathematical representation of and information about the system for which this VI generates the root locus, or Evans, plot.
	Gain Info specifies the initial and final gain values. K0 is the initial feedback gain value. The default is 0. Kf is the final feedback gain value. The default is 0.
	Gain specifies the feedback gain to apply to each open-loop model pole. Use this parameter to determine the feedback gain necessary to place an open-loop pole in a particular location. Each element of the Gain parameter corresponds to a different open-loop pole.
	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.
	Feedback specifies the type of feedback, positive or negative. 0 negative (default)—The closed-loop system has negative feedback. 1 positive—The closed-loop system has positive feedback.
	Minimum Number of Points specifies the minimum number of points this VI uses for the root locus plot. The default is 300 points.
	Root Locus Graph displays the Evans plot of a SISO feedback system on an XY graph. Right-click this terminal on the block diagram and select Create»Indicator from the shortcut menu to display this data in the CD Root Locus Plot indicator.
	Root Locus Data returns information about the root locus calculation. K is a 1D-array of m elements of all the gain values that this VI uses to create the root locus. Roots is an m x n array, where n is the number of poles in the closed-loop transfer function. The ith row of Roots consists of the n closed-loop poles that result when the feedback gain has value equal to the ith element of K.
	Root Locus Information returns information about the root locus plot, such as the bifurcation points and open-loop poles and zeros. Open-Loop Zeros returns the zeros of the open-loop system and the location of the closed-loop poles when the gain K equals infinity. Open-Loop Poles returns the poles of the closed-loop system when the gain K equals 0. Bifurcation Points returns the points in the root locus plot where a pair of real poles splits into a conjugate pair of poles. K at Bifurcation Point returns the gain values at which the bifurcation occurs in the root locus plot.
	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.

CD Root Locus with Gain Details

This VI does not support delays unless the delays are part of the mathematical model that represents the dynamic system. To account for the delays when calculating the dynamics of a system, you must incorporate the delays into the mathematical model of the dynamic system using the CD Convert Delay with Pade Approximation VI (continuous models) or the CD Convert Delay to Poles at Origin VI (discrete models). Refer to the LabVIEW Control Design Toolkit User Manual for more information about delays and the limitations of Pade Approximation.