Version 9.0 (R2010b) Control System Toolbox Software

This table summarizes what's new in Version 9.0 (R2010b):

New Features and Changes	Version Compatibility Considerations	Fixed Bugs and Known Problems
Yes Details below	Yes–Details labeled as Compatibility Considerations, below. See also Summary.	Bug Reports

New features introduced in this version:

• New Commands and GUI for Modeling and Tuning PID Controllers

• Improved PID Tuning Options in SISO Design Tool

• Ability to Analyze a Controller Design for Multiple Models Simultaneously in SISO Design Tool

• Change in Output of repsys Command

New Commands and GUI for Modeling and Tuning PID Controllers

This release introduces specialized tools for modeling and designing PID controllers.

PID Controller Design with the New PID Tuner GUI

The new PID Tuner GUI lets you interactively tune a PID controller for your required response characteristics. Using the GUI, you can adjust and analyze your controller's performance with response plots, such as reference tracking, load disturbance rejection, and controller effort, in both time and frequency domains.

The PID Tuner supports all types of SISO plant models, including:

• Continuous- or discrete-time plant models

• Stable, unstable, or integrating plant models

• Plant models that include I/O time delays or internal time delay

For more information about using PID Tuner, see:

• Designing PID Controllers in the Control System Toolbox Getting Started Guide

• The new demo Designing PID for Disturbance Rejection with PID Tuner

PID Controller Design with the New pidtune Command

The new pidtune command lets you tune PID controller gains at the command line.

pidtune automatically tunes the PID gains to balance performance (response time) and robustness (stability margins). You can specify your own response time and phase margin targets using the new pidtuneOptions command.

pidtune supports all types of SISO plant models, including:

• Continuous- or discrete-time plant models.

• Stable, unstable, or integrating plant models.

• Plant models that include I/O time delays or internal time delays.

• Arrays of plant models. If sys is an array, pidtune designs a separate controller for each plant in the array.

For additional information, see:

• The pidtune and pidtuneOptions reference pages

• The new Control System Toolbox demo Designing Cascade Control System with PI Controllers

Modeling PID Controllers in Parallel Form or Standard Form

The new LTI model objects pid and pidstd are specialized for modeling PID controllers.

With pid and pidstd you can model a PID controller directly with the PID parameters, expressed in parallel (pid) or standard (pidstd) form. The pid and pidstd commands can also convert to PID form any type of LTI object that represents a PID controller.

Previously, to model a PID controller, you had to derive the controller's equivalent transfer function (or other model), and could not directly store the PID parameters.

For additional information, see the pid and pidstd reference pages

Improved PID Tuning Options in SISO Design Tool

This release includes improvements to the PID Tuning options in the Automated Tuning pane of SISO Design Tool.

In addition to the Robust Response Time tuning algorithm, SISO Design Tool offers a collection of classical design formulas, including the following:

• Approximate M-Constrained Integral Gain Optimization (MIGO) Frequency Response

• Approximate MIGO Step Response

• Chien-Hrones-Reswick

• Skogestad Internal Model Control (IMC)

• Ziegler-Nichols Frequency Response

• Ziegler-Nichols Step Response

For information about using SISO Design Tool, see SISO Design Tool in the Control System Toolbox User's Guide. For specific information about the automatic PID Tuning options in SISO Design Tool, see PID Tuning in the Control System Toolbox User's Guide.

Ability to Analyze a Controller Design for Multiple Models Simultaneously in SISO Design Tool

You can now analyze a controller design for multiple models simultaneously using the SISO Design Tool. This feature helps you analyze whether the controller satisfies design requirements on a system whose exact dynamics are not known and may vary.

System dynamics can vary because of parameter variations or different operating conditions. You represent variations in system dynamics of the plant (G), sensor (H), or both in a feedback structure using arrays of LTI models. Then, design a controller for a nominal model in the array and analyze that the controller satisfies the design requirements on the remaining models using the design and analysis plots. For more information, see:

• Control Design Analysis of Multiple Models in the Control System Toolbox documentation.

• Compensator Design for a Set of Plant Models demo.

• Reference Tracking of a DC Motor with Parameter Variations demo in Simulink^® Control Design™ software.

Change in Output of repsys Command

The output of the repsys command when called with a single dimension argument has changed.

In prior versions, the output of repsys(sys,N) was the same as that of append(sys,...,sys).

Now, repsys(sys,N) returns the same result as repsys(sys,[N N]).

The results of other syntaxes for repsys have not changed.

See the repsys and append reference pages for more information.

Compatibility Consideration

Code that depends upon the previous result of repsys(sys,N) no longer returns that result. To obtain the previous result, replace repsys(sys,N) with sys*eye(N).

Version 9.1 (R2011a) Control System Toolbox Software

Version 8.5 (R2010a) Control System Toolbox Software

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