setTunedValue

Set current value of tuned variable in slTuner interface

Syntax

setTunedValue(st,var,value)

setTunedValue(st,varValues)

setTunedValue(st,model)

Description

setTunedValue lets you initialize or modify the current value of a tuned variable within an slTuner interface.

An slTuner interface parameterizes each tuned block as a Control Design Block, or a generalized parametric model of type genmat or genss. This parameterization specifies the tuned variables for commands such as systune.

setTunedValue(st,var,value) sets the current value of the tuned variable, var, in the slTuner interface, st.

setTunedValue(st,varValues) sets the values of multiple tuned variables in st using the structure, varValues.

setTunedValue(st,model) updates the values of the tuned variables in st to match their values in the generalized model model. To propagate tuned values from one model to another, use this syntax.

Examples

Set Value of Single Tunable Element within Custom Parameterization

Create an slTuner interface for the scdcascade model.

open_system('scdcascade')
st = slTuner('scdcascade',{'C1','C2'});

Set a custom parameterization for one of the tunable blocks.

C1CustParam = realp('Kp',1) + tf(1,[1 0]) * realp('Ki',1);
setBlockParam(st,'C1',C1CustParam);

These commands set the parameterization of the C1 controller block to a generalized state-space (genss) model containing two tunable parameters, Ki and Kp.

Initialize the value of Ki to 10 without changing the value of Kp.

setTunedValue(st,'Ki',10);

Set Value of Multiple Tunable Elements within Custom Parameterization

Create an slTuner interface for the scdcascade model.

open_system('scdcascade')
st = slTuner('scdcascade',{'C1','C2'});

Set a custom parameterization for one of the tunable blocks.

C1CustParam = realp('Kp',1) + tf(1,[1 0]) * realp('Ki',1);
setBlockParam(st,'C1',C1CustParam);

These commands set the parameterization of the C1 controller block to a generalized state-space (genss) model containing two tunable parameters, Ki and Kp.

Create a structure of tunable element values, setting Kp to 5 and Ki to 10.

S = struct('Kp',5,'Ki',10);

Set the values of the tunable elements in st.

setTunedValue(st,S);

Set Value of Tuned Block Parameterization Using Generalized State-Space Model

Convert an slTuner interface for the Simulink® model rct_diskdrive to a genss model to tune the model blocks using hinfstruct. After tuning, update the slTuner interface with the tuned parameters and write the parameter values to the Simulink model for validation.

Use of hinfstruct requires a Robust Control Toolbox™ license.

Create an slTuner interface for rct_diskdrive. Add C and F as tuned blocks of the interface.

open_system('rct_diskdrive');
st = slTuner('rct_diskdrive',{'C','F'});

The default parameterization of the transfer function block, F, is a transfer function with two free parameters. Because F is a low-pass filter, you must constrain its coefficients. To do so, specify a custom parameterization of F with filter coefficient a.

a = realp('a',1);
setBlockParam(st,'F',tf(a,[1 a]));

Convert st to a genss model.

m = getIOTransfer(st,{'r','n'},{'y','e'});

Typically, for tuning with hinfstruct, you append weighting functions to the genss model that depend on your design requirements. You then tune the augmented model. For more information, see Fixed-Structure H-infinity Synthesis with hinfstruct (Robust Control Toolbox).

For this example, instead of tuning the model, manually adjust the tuned variable values.

m.Blocks.C.Kp.Value = 0.00085;
m.Blocks.C.Ki.Value = 0.01;
m.Blocks.a.Value = 5500;

After tuning, update the block parameterization values in st.

setTunedValue(st,m);

This is equivalent to setBlockValue(st,m.Blocks).

To validate the tuning result in Simulink, first update the Simulink model with the tuned values.

writeBlockValue(st);

Input Arguments

st — Interface for tuning control systems modeled in Simulink^®

slTuner interface

Interface for tuning control systems modeled in Simulink, specified as an slTuner interface.

var — Tuned variable

character vector | string

Tuned variable within st, specified as a character vector or string. A tuned variable is any Control Design Block, such realp, tunableSS, or tunableGain, involved in the parameterization of a tuned Simulink block, either directly or through a generalized parametric model. To get a list of all tuned variables within st, use getTunedValue(st).

var can refer to the following:

• For a block parameterized by a Control Design Block, the name of the block. For example, if the parameterization of the block is

  C = tunableSS('C')

  then set var = 'C'.

• For a block parameterized by a genmat/genss model, M, the name of any Control Design Block listed in M.Blocks. For example, if the parameterization of the block is

  a = realp('a',1);
  C = tf(a,[1 a]);

  then set var = 'a'.

value — Value of tuned variable

numeric scalar | numeric array | state-space model

Value of tuned variable in st, specified as a numeric scalar, a numeric array or a state-space model that is compatible with the tuned variable. For example, if var is a scalar element such as a PID gain, value must be a scalar. If var is a 2–by–2 tunableGain, then value must be a 2–by–2 scalar array.

varValues — Values of multiple tuned variables

structure

Values of multiple tuned variables in st, specified as a structure with fields specified as numeric scalars, numeric arrays, or state-space models. The field names are the names of tuned variables in st. Only blocks common to st and varValues are updated, while all other blocks in st remain unchanged.

To specify varValues, you can retrieve and modify the tuned variable structure from st.

varValues = getTunedValue(st);
varValues.Ki = 10;

model — Tuned model

generalized LTI model

Tuned model that has some parameters in common with st, specified as a Generalized LTI Model. Only variables common to st and model are updated, while all other variables in st remain unchanged.

More About

Tuned Blocks

Tuned blocks, used by the slTuner interface, identify blocks in a Simulink model whose parameters are to be tuned to satisfy tuning goals. You can tune most Simulink blocks that represent linear elements such as gains, transfer functions, or state-space models. (For the complete list of blocks that support tuning, see How Tuned Simulink Blocks Are Parameterized). You can also tune more complex blocks such as SubSystem or S-Function blocks by specifying an equivalent tunable linear model.

Use tuning commands such as systune to tune the parameters of tuned blocks.

You must specify tuned blocks (for example, C1 and C2) when you create an slTuner interface.

st = slTuner('scdcascade',{'C1','C2'})

You can modify the list of tuned blocks using addBlock and removeBlock.

To interact with the tuned blocks use:

• getBlockParam, getBlockValue, and getTunedValue to access the tuned block parameterizations and their current values.

• setBlockParam, setBlockValue, and setTunedValue to modify the tuned block parameterizations and their values.

• writeBlockValue to update the blocks in a Simulink model with the current values of the tuned block parameterizations.

Tuned Variables

Within an slTuner interface, tuned variables are any Control Design Blocks involved in the parameterization of a tuned Simulink block, either directly or through a generalized parametric model. Tuned variables are the parameters manipulated by tuning commands such as systune.

For Simulink blocks parameterized by a generalized model or a tunable surface:

• getBlockValue provides access to the overall value of the block parameterization. To access the values of the tuned variables within the block parameterization, use getTunedValue.

• setBlockValue cannot be used to modify the block value. To modify the values of tuned variables within the block parameterization, use setTunedValue.

For Simulink blocks parameterized by a Control Design Block, the block itself is the tuned variable. To modify the block value, you can use either setBlockValue or setTunedValue. Similarly, you can retrieve the block value using either getBlockValue or getTunedValue.

Version History

Introduced in R2015b