Timed-Based Linearization

Generate linear models in base workspace at specific times

• 

Libraries:
Simulink / Model-Wide Utilities

Description

This block calls linmod or dlinmod to create a linear model for the system when the simulation clock reaches the time specified by the Linearization time parameter. 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 _Timed_Based_Linearization, for example, vdp_Timed_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 operating point time (OperPoint.t). The states (OperPoint.x) and inputs (OperPoint.u) fields are not used.
Ts	The sample time of the linearization for a discrete linearization

Tip

To generate models conditionally, use the Trigger-Based Linearization block.

Examples

Generate Linear Models at Predetermined Times

This example shows how to use the Timed-Based Linearization block to generate linear models at predetermined times.

In this model, the Linearization time of the Timed-Based Linearization block is set to [2 5]. On the Data Import/Export pane of the Model Configuration Parameters dialog box, the States and Time check boxes are selected. These settings enable you to get the states of the model at the simulation times of 2 and 5 seconds.

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

• ex_f14_linearization_Timed_Based_Linearization

• tout

• xout

To get the indices to the operating point times, execute the following command:

ind1 = find(ex_f14_linearization_Timed_Based_Linearization(1).OperPoint.t==tout);

To get the state vectors at the operating points, execute the following command:

ind2 = find(ex_f14_linearization_Timed_Based_Linearization(1).OperPoint.t==tout);

Parameters

Linearization time — Time at which to generate a linear model

1 (default) | scalar | vector

Time at which you want the block to generate a linear model. Enter a vector of times if you want the block to generate linear models at more than one time step.

Programmatic Use

Block Parameter: LinearizationTime

Type: character vector

Values: scalar | vector

Default: '1'

Sample time (of linearized model) — Sample time

0 (default) | scalar | vector

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
Direct Feedthrough	no
Multidimensional Signals	no
Variable-Size Signals	no
Zero-Crossing Detection	no

Version History

Introduced in R2010a