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Contents

Index

• Getting Started

Key Features

About This Tutorial

PID Control Design Using Robust-Response-Time Tuning Algorithm

PID Control Design Using Bode Graphical Tuning

Closed-Loop Simulation of Simulink Model

• User's Guide

• Blocks

• Functions

• Linearization Analysis I/Os

• Steady-State Operating Points

• Linearization

• Frequency Response Estimation

• Interface for Compensator Tuning

• Release Notes

looptune - Class: slTunable

Tune MIMO control systems in Simulink

Syntax

[ST,gam,info] = looptune(ST0,wc) [ST,gam,info] = looptune(ST0,wc,Req1,Req2,...) [ST,gam,info] = looptune(...,options)

Description

[ST,gam,info] = looptune(ST0,wc) tunes the Simulink control system described by the slTunable interface ST0 to meet the following default requirements:

Bandwidth — Gain crossover for each loop falls in the frequency interval wc
Performance — Integral action at frequencies below wc
Robustness — Adequate stability margins and gain roll-off at frequencies above wc

[ST,gam,info] = looptune(ST0,wc,Req1,Req2,...) tunes the feedback loop to meet additional design requirements specified in one or more tuning goal objects Req. Omit wc to use the requirements specified in the Req objects instead of an explicit target crossover frequency and the default performance and robustness requirements.

[ST,gam,info] = looptune(...,options) specifies further options, including target gain margin, target phase margin, and computational options for the tuning algorithm.

Tips

slTunable.looptune allows you to use the Robust Control Toolbox tuning command looptune on a control system described in a Simulink model. Using slTunable provides an interface between the Simulink model and the looptune command, allowing you to identify the tunable components of the system for looptune to tune. Using slTunable.looptune requires Robust Control Toolbox software.

Input Arguments

`ST0`	`slTunable` interface object representing the Simulink control system to tune. For information on how to create and configure the `slTunable` interface, see the `slTunable` reference page.
`wc`	Vector specifying the target crossover region `[wcmin,wcmax]`. The `looptune` command attempts to tune all loops in the control system so that the open-loop gain crosses 0 dB within the target crossover region. A scalar `wc` specifies the target crossover region `[wc/2,2*wc]`.
`Req`	One or more `TuningGoal` objects specifying design requirements. Available requirement types are: `TuningGoal.Tracking` — Setpoint tracking requirement `TuningGoal.MaxGain` — Limit on transfer function gain `TuningGoal.LoopShape` — Target shape for open-loop response Any input or output signal names that you specify in a `TuningGoal` object must appear in the `Controls` or `Measurements` properties of `SL0`. See the `slTunable` reference page for more information.
`options`	Set of options for the `looptune` algorithm, specified using `looptuneOptions`. See `looptuneOptions` for information about the available options, including target gain margin and phase margin.

Output Arguments

ST

Tuned version of ST0.

Use slTunable.loopview to graphically validate the design. Use slTunable.writeBlockValue to apply the tuned parameter values to the Simulink model.

gam

Parameter indicating degree of success at meeting all tuning constraints. A value of gam <= 1 indicates that all requirements are satisfied. A value of gam >> 1 indicates failure to meet at least one requirement. Use slTunable.loopview to visualize the tuned result and identify the unsatisfied requirement.

For best results, use the RandomStart option in looptuneOptions to obtain several minimization runs. Setting RandomStart to an integer N > 0 causes looptune to run the optimization N additional times, beginning from parameter values it chooses randomly. You can examine gam for each run to help identify an optimization result that meets your design requirements.

info

Structure containing the following tuning data:

Optimal I/O scalings Di and Do
Requirement parameters and weighting functions

To use the data in info, use the command loopview(ST,info) to visualize tuning constraints and validate the tuned design. See slTunable.loopview for more information.