Hi,
Can sombody help me… please
I have a formula, from which I need a simulink model.
Thank you in advance…
MATLAB: Simulink modeling problem
modelsimulink
Related Solutions
To model differential equations in Simulink, you should follow these steps:
- First, make a list of all the constant valued variables used in the equations you are trying to model. Then, load these variables with their values in the workspace before starting to prepare the model.
- For example, lets an ODE be:
- To model this ODE, a block should be needed which can integrate x_dot(t) to x(t) . The “Integrator” block from the “Math Operations” library of Simulink can do that. Blocks that contain continuous states, such as “Integrator block”, can accurately model the dynamics described by ODEs because the Simulink solvers can control the integration error of a continuous state. One important point here to note that you should not use the “Derivative block” to model ODEs. “Derivative block” only approximates the rate of change of its input signals but doesn’t contain any continuous state. Hence, this block has no ability on controlling simulation accuracy. Thus, find how many “Integrator blocks” will be required in your case first and avoid using “Derivative block”.
- Start with the Integrator blocks and label their inputs and outputs properly:
- You can model the constant valued variables using “Constant” block from “Math Operations” library.
- To perform addition use “Add” block, for multiplication use “Product” block and for division use “Divide” block from “Math Operations” library.
- To multiply any signal with a constant factor, use “Gain” block from “Math Operations” library.
- Now, construct the equation’s RHS and then connect the returned signal from the equation’s RHS as a source to its left side.
- In this example, the equation can be simplified as follows:
- The Simulink model will now look like this:
- Now, as per above example, you can rewrite your ODEs and follow this step for one ODE at a time to model your system of equations.
- Finally put the initials conditions in the Integrator Block if any.
I now found a way to obtain the expression of the identified nlarx model.
Assume the name of the identified model is m. Then we can try the following commands;
w=get(m,'Nonlinearity'); w.parameters;
The answer will give us the values of the coefficients of the nlarx model. The form with nonlinearity estimator of nlarx model can be found in the MatLab help file.
Here I would like to thank Dr. Piovoso. He helped to find these command.
I would like to thank Rajiv Singh as well. His answer helped me to know the nonlinear identification further.
Best Answer