Since F = 0 in the free-motion test data, the frequency
e à à responses h11 = Fh Ym Fe=0 and h21 = −Ys Ym Fe=0
can be found by applying the spectral analysis function spa of MATLAB. Also, by using contact-mode test data, the other two hybrid parameters can be obtained as h12 =
FF−hYFandh=−YF−hYF[22]. he11me 22 se21me