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

Simulink Parameter Estimation

Creating Estimation Objects

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What is an Estimation Object Constructor Properties of Estimation Objects Example: F14 Model Modifying Properties Using Class Methods

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What is an Estimation Object

Constructor

Properties of Estimation Objects

Example: F14 Model

Modifying Properties

Using Class Methods

What is an Estimation Object

The @Estimation object is the coordinator between the model, experiments, and parameter objects.

Constructor

The @Estimation object is the coordinator of the model, experiment, and parameter objects. The syntax to create an estimation object is

h = ParameterEstimator.Estimation('model');
h = ParameterEstimator.Estimation('model', hParam);
h = ParameterEstimator.Estimation('model', hParam, hExps);

Properties of Estimation Objects

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

Estimation Object Properties

Property	Description
`Model`	Name of the Simulink model with which this estimation is associated.
`Experiments`	Experiments to be used in estimations. For multiple experiments, the cost function uses a concatenation of the output error vectors obtained using each experimental data set.
`Parameters`	Parameter objects to be used in estimations.
`States`	State objects to be used in estimations. This is a handle matrix with as many columns as there are experiments, and as many rows as there are states in `Model`. The handle matrix is created automatically in the constructor. You can reorganize its rows to specify shared states between experiments, and set the `Estimated` flag of desired states. If state data is provided in an experiment, the state objects stored in the columns of this matrix are initialized from the experiments.
`SimOptions`	Same as `simset` structure. This property is initialized to `simget(this.Model)`.
`OptimOptions`	Same as `optimset` structure.
`EstimInfo`	This property is used to store estimation-related information at each iteration of the optimizer, and is initialized as this.EstimInfo = struct( 'Cost', [],... 'Covariance', [],... 'FCount', [],... 'FirstOrd', [],... 'Gradient', [],... 'Iteration', [],... 'Procedure', [],... 'StepSize', [],... 'Values', [] );

Example: F14 Model

To create an estimation object for the f14 model to estimate the parameters Ta and Kf and two states, use

exp1 = ParameterEstimator.TransientExperiment(gcs);
par1 = ParameterEstimator.Parameter('Ta', 'Estimated', true);
par2 = ParameterEstimator.Parameter('Kf', 'Estimated', true);
est1 = ParameterEstimator.Estimation(gcs, [par1, par2], exp1);
est1.States(1,1).Estimated = true;
est1.States(6,1).Estimated = true;
est1

MATLAB returns

Estimated variables for the model 'f14':

Estimated Parameters

Using Experiments
   (1) f14 experiment

Estimated States for Experiment 'f14 experiment' 
   (1) f14/Actuator Model
   (6) f14/Controller/Proportional plus integral compensator

Modifying Properties

After an estimation object is created, you can modify its properties using this syntax:

est.OptimOptions.Algorithm = 'fmincon'; % Estimation method
est.OptimOptions.Display = 'iter'; % Show estimation information 
...in workspace
est.Parameters(1).Estimated = false; % Do not estimate first 
...parameter
est.States(2,3).Estimated = false; % Do not estimate second state 
...of third expression

Using Class Methods

Descriptions of some of the important methods are given next:

compare — Compares an experiment and a simulation.
simulate — Simulates the model with current parameters and states.
estimate — Runs an estimation.
restart — Restarts an estimation after it has finished running.
update — Updates the estimation object after the Simulink model has been modified.

Creating State Objects

Blocks — Alphabetical List

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