How to force a variable to a value in Simscape language?

Hello everybody,

I'm modeling a poppet valve.

The poppet position is described as follows:

            v.der == 1/m * ( A.p*A1 - B.p*A2 - k*x0 - k * x - c* x.der);
            x.der == v;

I have to set a limit to the poppet position x, kind of:

if x > Xmax
x == Xmax
end

I tried with a let-in with if-else enclosed, but it says I can't pass .der to if statement.

Does anybody have any idea?

Thanks

Paolo

Answer 1

[Arnav Mendiratta]

As long as x.der and v.der are valid variables containing a scalar values or array, the '>' operator should work. With your code, it's hard to tell what all these variables are. This happens possibly because you are assigning a struct to x.der in this line:

x.der == v;      % v is a stuct from previous line

And then, within your if-else, you are comparing a struct ('x') with a scalar value ('Xmax').

Instead of using if-else statement, a better approach is to use "assert" to test that all your variables are valid. Refer to the documentation here:

https://www.mathworks.com/help/matlab/ref/assert.html