How to create a custom component in Simscape, with input as variable parameter ?

Hello,

I am trying to create a custom component in Simscape, based on the "Tire (Friction Parameterized)" component.

Basically, I want some of its parameters, lets say the "rolling radius", to be an input of the component, so that I can change its value during the simulation, just as I can change the value of a "variable inertia" with a PS input.

I tried to create some new inputs in the source code, but it seems that I can't use these inputs in the equations, as they are not defined as parameters. I also tried to define new equations, to impose the value as the parameter to be the same as the input, but then I have more equations than parameters.

Any idea on how to solve this issue ? Maybe the method consisting of using those parameters as input is not the best one, I am open to other solutions.

[MULI]

Hi @Neil,

If you are trying to modify the "Tire (Friction Parameterized)" component to allow parameters like the rolling radius to be changed dynamically during the simulation you can consider the following approach:

• Instead of defining "r_tire" as a parameter, you can define it as a variable so it can change over time:

variables
    r_tire = {0.3, 'm'}; % Rolling radius (Now a variable instead of a parameter)
end

• Now link "r_tire" to the input "Radius" using an equation:

equations
    r_tire == Radius;  % Assign the input value dynamically
end

• Now, just replace "r_tire" wherever you were using it as a parameter in the model equations.

These modifications might help you to update the rolling radius dynamically based on the input signal during simulation.

[Neil]

Hi @MULI

Thank you for your answer.

I have added your modifications in my code, but unfortunaley, I am unable to generate the block in Simulink (see error in the attached image).

It seems that the format "variable" is not working in some equations.

Do you have any solution ?