Sensitivity analysis of a Continuous-time nonlinear grey-box model

Hello,

Please help me on this. I need to make a sensitivity analysis of the parameters of a Continuous-time nonlinear grey-box model.

Specificially, i have the following Continuous-time nonlinear grey-box model created with the idnlgrey function.

nlgr =

Continuous-time nonlinear grey-box model defined by 'simpl' (MATLAB file):

dx/dt = F(t, u(t), x(t), p1, ..., p13)

y(t) = H(t, u(t), x(t), p1, ..., p13) + e(t)

with 2 input(s), 2 state(s), 2 output(s), and 13 free parameter(s) (out of 13).

Status:

Created by direct construction or transformation. Not estimated.

Which is the easiest way to identify the critical model parameters?

Thanks in advance