linio

Create linear analysis point for Simulink model, Linear Analysis Plots block, or Model Verification block

Syntax

io = linio(block,port)

io = linio(block,port,type)

io = linio(block,port,type,[],busElement)

Description

io = linio(block,port) creates a linearization I/O object that represents an input perturbation analysis point for the signal that originates from the specified output port of a Simulink^® block.

io = linio(block,port,type) creates an analysis point of the specified type.

io = linio(block,port,type,[],busElement) creates an analysis point for an element of a bus signal.

Examples

Create Analysis Points for Simulink Model

Open Simulink model.

open_system('magball')

To specify multiple analysis points for linearization, create a vector of linearization I/O objects.

Create an input perturbation analysis point at the output port of the Controller block.

io(1) = linio('magball/Controller',1);

Create an open-loop output analysis point at the output of the Magnetic Ball Plant block. An open-loop output point is an output measurement followed by a loop opening.

io(2) = linio('magball/Magnetic Ball Plant',1,'openoutput');

View the specified analysis points.

io

1x2 vector of Linearization IOs: 
--------------------------
1. Linearization input perturbation located at the following signal:
- Block: magball/Controller
- Port: 1
2. Linearization open-loop output located at the following signal:
- Block: magball/Magnetic Ball Plant
- Port: 1

You can use these analysis points to linearize only the Magnetic Ball Plant subsystem. To do so, pass io to the linearize command or to an slLinearizer interface.

Unlike specifying analysis points directly in the Simulink model, when you create analysis points using linio, no annotations are added to the model.

Select Individual Bus Element as Analysis Point

Open Simulink model.

mdl = 'scdbusselection';
open_system(mdl)

The COUNTERBUS signal, which originates from the COUNTERBUSCreator block, contains multiple bus elements.

Specify the upper_saturation_limit bus element as a linearization input. Select this element using dot notation, since it is within the nested limits bus.

io = linio('scdbusselection/COUNTERBUSCreator',1,'input',[],...
           'limits.upper_saturation_limit');

Input Arguments

block — Simulink block

character vector | string

Simulink block from which the analysis point originates, specified as a character vector or string that contains its full block path. For example, to mark an analysis point at an output of the Controller block in the magball model, specify block as 'magball/Controller'.

port — Output port

positive integer

Output port of block from which the analysis point originates, specified as a positive integer.

port must be a valid port number for the specified block.

type — Analysis point type

'input' (default) | 'output' | 'loopbreak' | ...

Analysis point type, specified as one of the following:

• 'input' — Input perturbation

• 'output' — Output measurement

• 'loopbreak' — Loop break

• 'openinput' — Open-loop input

• 'openoutput' — Open-loop output

• 'looptransfer' — Loop transfer

• 'sensitivity' — Sensitivity

• 'compsensitivity' — Complementary sensitivity

For more information on analysis point types, see Specify Portion of Model to Linearize.

busElement — Bus element name

character vector | string

Bus element name, specified as a character vector or string. When adding elements within a nested bus structure, use dot notation to access the elements of the nested bus. For an example, see Select Individual Bus Element as Analysis Point.

Output Arguments

io — Analysis point

linearization I/O object

Analysis point, returned as a linearization I/O object. Use io to specify a linearization input, output, or loop opening when using the linearize command. For more information, see Specify Portion of Model to Linearize.

Each linearization I/O object has the following properties:

Property	Description
Active	Flag indicating whether to use the analysis point for linearization, specified as one of the following: 'on' — Use the analysis point for linearization. This value is the default option. 'off' — Do not use the analysis point for linearization. Use this option if you have an existing set of analysis points and you want to linearize a model with a subset of these points.
Block	Full block path of the block with which the analysis point is associated, specified as a character vector.
PortNumber	Output port with which the analysis point is associated, specified as an integer.
Type	Analysis point type, specified as one of the following: 'input' — Input perturbation 'output' — Output measurement 'loopbreak' — Loop break 'openinput' — Open-loop input 'openoutput' — Open-loop output 'looptransfer' — Loop transfer 'sensitivity' — Sensitivity 'compsensitivity' — Complementary sensitivity For more information on analysis point types, see Specify Portion of Model to Linearize.
BusElement	Bus element name with which the analysis point is associated, specified as a character vector or '' if the analysis point is not a bus element.
Description	User-specified description of the analysis point, which you can set for convenience, specified as a character vector.

Alternative Functionality

Model Linearizer

You can interactively configure analysis points using the Model Linearizer. For more information see, Specify Portion of Model to Linearize in Model Linearizer.

Simulink Model

You can also specify analysis points directly in a Simulink model. When you do so, the analysis points are saved within the model. For more information, see Specify Portion of Model to Linearize in Simulink Model.

slLinearizer and slTuner Interfaces

If you want to obtain multiple open-loop or closed-loop transfer functions from the linearized system without recompiling the model, you can specify linear analysis points using an slLinearizer interface. For more information, see Mark Signals of Interest for Batch Linearization. Similarly, if you want to tune a control system and obtain multiple open-loop or closed-loop transfer functions from the resulting system, you can specify linear analysis points using an slTuner interface. For more information, see Mark Signals of Interest for Control System Analysis and Design.

Version History

Introduced before R2006a