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Trigger-Based Linearization

Generate linear models in base workspace when triggered

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  • Trigger-Based Linearization block

Libraries:
Simulink / Model-Wide Utilities

Description

When triggered, this block calls linmod or dlinmod to create a linear model for the system at the current operating point. No trimming is performed. The linear model is stored in the base workspace as a structure, along with information about the operating point at which the snapshot was taken. Multiple snapshots are appended to form an array of structures.

Note

linmod and dlinmod provide only basic linearization functionality. For full linearization functionality, use Simulink® Control Design™ software. For more information, see Choose Linearization Tools (Simulink Control Design).

The block sets the following model parameters to the indicated values:

  • BufferReuse = 'off'

  • BlockReductionOpt = 'off'

The name of the structure used to save the snapshots is the name of the model appended by _Trigger_Based_Linearization, for example, vdp_Trigger_Based_Linearization. The structure has the following fields:

Field

Description

a

The A matrix of the linearization

b

The B matrix of the linearization

c

The C matrix of the linearization

d

The D matrix of the linearization

StateName

Names of the model's states

OutputName

Names of the model's output ports

InputName

Names of the model's input ports

OperPoint

A structure that specifies the operating point of the linearization. The structure specifies the value of the model's states (OperPoint.x) and inputs (OperPoint.u) at the operating point time (OperPoint.t).

Ts

The sample time of the linearization for a discrete linearization

Tip

Use the Timed-Based Linearization block to generate linear models at predetermined times.

Examples

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Open Model

You can use state and simulation time logging to extract the model states at operating points. In this example, the model is configured to get the states when the x1 signal triggers the Trigger-Based Linearization block on a rising edge.

In this model, the Trigger type of the Trigger-Based Linearization block is set to rising. On the Data Import/Export pane of the Model Configuration Parameters dialog box, the States and Time check boxes are selected.

After simulating the model, the following variables appear in the MATLAB® workspace:

  • ex_vdp_triggered_linearization_Trigger_Based_Linearization

  • tout

  • xout

To get the index to the first operating point time, execute the following command:

ind1 = find(ex_vdp_triggered_linearization_Trigger_Based_Linearization(1).OperPoint.t==tout);

To get the state vector at this operating point, execute the following command:

x1 = xout(ind1,:);

Ports

Input

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Input trigger signal, specified as a scalar. Specify the type of event that triggers generation of a linear model using the Trigger type parameter.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | fixed point

Parameters

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Type of event on the trigger input signal that triggers generation of a linear model. You can select:

  • rising — Trigger execution of subsystem or model when the trigger signal rises from a negative or zero value to a positive value. If the initial value is negative, a rising signal to zero triggers execution.

  • falling — Trigger execution of subsystem or model when the trigger signal falls from a positive or a zero value to a negative value. If the initial value is positive, a falling signal to zero triggers execution.

  • either — Trigger execution of subsystem or model when the trigger signal is either rising or falling.

  • function-call — Trigger execution of subsystem or model when the trigger signal is a function-call event from a Stateflow® chart, Function-Call Generator block, S-Function block, or Hit Crossing block.

Programmatic Use

Block Parameter: TriggerType
Type: character vector
Values: 'rising' | 'falling' | 'either' | 'function-call'
Default: 'rising'

Specify a sample time for the linear model. To create a continuous-time model using linmod, specify a sample time of 0. Otherwise, to create a discrete-time model using dlinmod, specify a positive sample time.

Programmatic Use

Block Parameter: SampleTime
Type: character vector
Values: scalar | vector
Default: '0'

Block Characteristics

Data Types

Boolean | double | fixed point | integer | single

Direct Feedthrough

no

Multidimensional Signals

no

Variable-Size Signals

no

Zero-Crossing Detection

no

Extended Capabilities

Fixed-Point Conversion
Design and simulate fixed-point systems using Fixed-Point Designer™.

Version History

Introduced before R2006a

See Also

Blocks

Functions