  We cast the $q$-rotor in the framework of Barnett-Pegg theory for rotation
angle, whose underlying algebra is $SU_q(2)$. A new method to fix the
deformation parameter from the theory is suggested. We test our ideas by
fitting rotational spectra in deformed even-even and superdeformed nuclei. The
results are in good agreement with the previous phenomenological applications
of $q$-rotor model.
