Synthesis Page (Interactive Control Design Dialog Box)

Requires: Control Design and Simulation Module

Guide to interactive control design process

This topic describes the Synthesis page of the Interactive Control Design dialog box you access through the SISO Controller function or the CD Interactive Control Design VI. Use this page in conjunction with the following pages in the same interface to design and analyze a controller:

• Configuration
• Specifications
• Analysis

Tip  Use features that allow you to analyze the system and controller more effectively.

Dialog Box Options

Dialog Box Options

Parameter	Description
Interactive Root Locus	Plots the root locus controller. Closed-loop poles appear red. You can move the closed-loop poles to change the closed-loop gain by clicking and dragging the poles on the graph. You can tune the gain by changing position of the closed-loop poles. Controller poles and zeros appear blue. Open-loop poles or zeros appear gray. You cannot move open-loop poles or zeros.
Step Response	Displays the output of the system when it is excited by a step input.
Interactive Open-Loop Bode Magnitude	Displays the Bode magnitude of an open-loop transfer function defined by the loop transfer function, which calculates the controller in series with the plant, sensor (if any), and actuator (if any) (CAPH). Closed-loop poles appear red. You can move the closed-loop poles to change the closed-loop gain by clicking and dragging the poles on the graph. Controller poles and zeros appear blue. You cannot move open-loop poles or zeros.
Interactive Bode Phase	Displays the phase (in degrees) of the model plotted against a set of frequencies.
Controller Type	Choose from the following types of controllers to implement. When you change the controller type to Interconnected or Custom, LabVIEW transfers the design from the previous controller type to the design for the Interconnected or Custom controller. PID—Contains the following options for implementing a PID controller in academic, parallel, or series form: PID Topology—Specifies the form to use to construct the PID model. Click the equation to choose from the available model types. Proportional—Specifies the proportional gain of the controller. In the equation that defines the PID form, Kc represents the proportional gain. Integral—Specifies the controller parameter that adjusts the effect of the integral term on the controller output. Derivative—Specifies the controller parameter that adjusts the effect of the error derivative term on the controller output. PID Alpha—Specifies the derivative filter time constant. Increasing this value increases damping of derivative action. This option is available only when the Derivative checkbox contains a checkmark. Lead/Lag—Contains the following options for implementing a phase lead or phase lag controller: Lead/Lag Topology—Specifies the type of lead or lag controller model you want to construct. Click the equation to choose from the available model types. Lead/Lag Gain (K)—Specifies the gain of the controller model equation. Time Constant (tau)—Specifies the time constant, in seconds, of the controller model equation. Alpha—Specifies the alpha parameter of the controller model equation. This option is available only if Lead/Lag Topology is Phase Lead below 0 dB or Phase Lead above 0 dB. Beta—Specifies the beta parameter of the controller model equation. This option is available only if Lead/Lag Topology is Phase Lag above 0 dB or Phase Lag below 0 dB. Maximum Phase Frequency (rad/s)—Returns the frequency, in radians per second, at which the maximum phase of the phase-lead or phase-lag controller occurs. Maximum Phase Difference (deg)—Returns the maximum phase, in degrees, of the controller. Filter—Contains the following options for configuring a Butterworth filter to include in the system: Filter Topology—Specifies the passband of the filter you want to create: lowpass, highpass, bandpass, or bandstop (notch). Filter Order—Specifies the order of the coefficients this function generates to create the filter. Filter Gain (K)—Specifies the gain of the filter. Cutoff Frequency (Fc)—Specifies the cutoff frequency, in radians per second, of the filter. If Filter Topology is Bandpass or Bandstop (notch), this value represents the center frequency of the filter. Band Frequency (Fs)—Specifies the frequency range of the filter. This option is available only if Filter Topology is Bandpass or Bandstop (notch). Interconnected—Contains the following options for designing different types of controllers and connecting them in series: Add PID—Specifies to include a PID controller in the series of connected controllers. When you place a checkmark in this checkbox, LabVIEW displays a PID tab that provides parameters for synthesizing the PID controller in series. The PID tab contains the same components you see when you select PID as the Controller Type. Add Lead/Lag—Specifies to include a phase-lead or phase-lag controller in the series of connected controllers. When you place a checkmark in this checkbox, LabVIEW displays a Lead/Lag tab that provides parameters for synthesizing the controller in series. The Lead/Lag tab contains the same components you see when you select Lead/Lag as the Controller Type. Add Filter—Specifies to include a filter in the series of connected controllers. When you place a checkmark in this checkbox, LabVIEW displays a Filter tab that provides parameters for synthesizing the filter in series. The Filter tab contains the same components you see when you select Filter as the Controller Type. Interconnected Gain—Specifies the scalar gain of the SISO system. Interconnected Controller Zeros—Displays the array of zeros of the model. The zeros can be real or complex. Interconnected Controller Poles—Displays the array of poles of the model. The poles can be real or complex. Custom—Contains options for designing a controller whose poles and zeros you define manually. When you select the Custom controller type, the following buttons display at the top of the page and allow you to add, move, and remove controller poles and zeros in the root locus and Bode magnitude graphs. This page contains the following buttons and options, from top to bottom: Add Real Pole—Adds a single pole to the controller on the real axis. The imaginary part of the pole is zero. To add the pole to the plot, click the Add Real Pole button then click the location on the plot at which you want to place the pole. You can move the pole after you place it on the plot by clicking the Move Pole or Zero button and then clicking and dragging the pole around the plot. Add Complex Pole—Adds a complex conjugate pole to the controller. To add the pole to the plot, click the Add Complex Pole button then click the location on the plot at which you want to place the pole. The step automatically adds the complex conjugate to the plot. You can move the pole after you place it on the plot by clicking the Move Pole or Zero button and then clicking and dragging the pole around the plot. Add Real Zero—Adds a single zero to the controller on the real axis. The imaginary part of the zero is zero. To add the zero to the plot, click the Add Real Zero button then click the location on the plot at which you want to place the zero. You can move the zero after you place it on the plot by clicking the Move Pole or Zero button and then clicking and dragging the zero around the plot. Add Complex Zero—Adds a complex conjugate zero to the controller. To add the zero to the plot, click the Add Complex Zero button then click the location on the plot at which you want to place the zero. The step automatically adds the complex conjugate to the plot. You can move the zero after you place it on the plot by clicking the Move Pole or Zero button and then clicking and dragging the zero around the plot. Remove Pole or Zero—Removes the controller pole or zero from the root locus or Bode magnitude graph. Move Pole or Zero—Enables you to click and drag a controller pole or zero from the root locus or Bode magnitude graph. Gain—Specifies the gain the controller uses in the feedback loop. Center to poles—Automatically adjusts the graph scales to center the plot in the dynamics of the system. Controller zeros—Defines the array of zeros of the model. The zeros can be real or complex. If they are complex, they must be in complex conjugate pairs. This table automatically calculates the complex conjugate pairs when you enter the real and imaginary parts followed by the symbol, i. For example, if you type –1 + 0.5i, this table generates the complex conjugate –1 ± 0.5i, which is equivalent to (–1 + 0.5i) * (–1 – 0.5i). Controller poles—Defines the array of poles of the model. The poles can be real or complex. If they are complex, they must be in complex conjugate pairs. This table automatically calculates the complex conjugate pairs when you enter the real and imaginary parts followed by the symbol, i. For example, if you type –1 + 0.5i, this table generates the complex conjugate –1 ± 0.5i, which is equivalent to (–1 + 0.5i) * (–1 – 0.5i).