Can I use a range when I estimate coefficients to fit given solution with grey box estimation?

Hi all,

When I'm estimating coefficients of ODEs to fit given solution, I sometimes get crazy estimations when I change the startvalues. Is it by any chance possible to give a range in which the estimations should be?

Suppose I'm estimating gravity, I could for example say that it should be between 8 and 11.

(the procedure I'm using: https://nl.mathworks.com/help/ident/ug/estimating-coefficients-of-odes-to-fit-given-solution.html)

Thanks in advance!

Answer 1

[Widagdo Purbowaskito]

Yes you can do that.

First you need to set your inital system through idgrey function, init_sys = idgrey(odefun,parameters,fcn_type,extra_args,Ts);

Then, you can set your parameters boundaries: init_sys.Structure.Parameters.Minimum(1) = 8; init_sys.Structure.Parameters.Maximum(1) = 11;

This will depends on how many parameters you want to set the boundary.