Creating State Objects :: Estimating from the Command Line (Simulink Parameter Estimation)

Simulink Parameter Estimation

Creating State Objects

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What is a State Object Constructor Properties of State Objects Example: F14 Model Modifying Properties Using Class Methods

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What is a State Object

Constructor

Properties of State Objects

Example: F14 Model

Modifying Properties

Using Class Methods

What is a State Object

The @State object is similar to the @Parameter object. One @State object corresponds to each Simulink block with states in the model.

Constructor

The syntax to create a state object is

h = ParameterEstimator.State('block');
h = ParameterEstimator.State('block', Value);
h = ParameterEstimator.State('block', Value, Minimum, 
    Maximum);

In the first case, the state vector is initialized from the model containing the block. In the other cases, block does not need to exist in the workspace at the time of object creation. However, it is required at estimation time.

Properties of State Objects

Descriptions of some important properties of state objects are given in the following table.

State Object Properties

Property	Description
`Block`	Name of the Simulink block whose states are defined by this object.
`Dimensions`	Scalar value to store the number of states of the relevant block.
`Value`	Column vector to store the value of the state for the block specified by this object. The length of this vector should be consistent with the `Dimensions` property.
`Estimated`	A Boolean array of the same size as that of `Value`. Depending on the value of the elements of the `Estimated` property, the behavior of the corresponding elements of `Value` is as follows: The elements of `Value` are estimated if the corresponding elements in `Estimate` are set to true. The result is stored in the `Value` property. The elements of `Value` are not estimated if the corresponding elements in `Estimated` are set to false. However, these elements are used to reset the corresponding states during estimations. This property is set to false by default, meaning that the state value is not estimated.
`InitialGuess`	Separate properties are required to hold the initial and current values of the states. So, when the `InitialGuess` property is initialized with a value, both it and the `Value` property are assigned the same value. Depending on the value of the elements of the `Estimated` property, the behavior of the corresponding elements of `InitialGuess` is as follows: If any element in `Estimated` is set to true, then the corresponding element of `InitialGuess` is used to initialize the state during estimations. If any element in `Estimated` is set to false, then the corresponding element of `InitialGuess` is not used in any way.
`Minimum`, `Maximum`	State vector range.
`TypicalValue`	The typical values of the states. This property is used in estimations for scaling purposes. The default value is `1`.
`Ts`	Sampling time of discrete blocks. Set to zero for continuous blocks. This property is read-only and is currently used for information only.
`Domain`	String to hold the physical domain of the block. Used for SimMechanics or SimPowerSystems blocks with states.

Example: F14 Model

To create a state object for the f14/Actuator Model block in the f14 model, use

st1 = ParameterEstimator.State(gcb)

MATLAB returns

(1) State data for f14/Actuator Model block:

    The block has 1 continuous state(s).

           State value : 0
         Initial guess : 0
             Estimated : false

Modifying Properties

After a state object is created, you can modify its properties using this syntax:

ic1.Estimated = true; % Estimate this state

Most of the properties, for example, Estimated and TypicalValue, support scalar expansion with respect to the size of Value.

Using Class Methods

Description of two important methods are given next:

hiliteBlock — Highlights the referenced blocks associated with state objects in the Simulink diagram.
update — Updates the state object after the Simulink model has been modified. If the size of Value property changes, then the other properties are reset to their default values.

Creating Parameter Objects

Creating Estimation Objects

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