For rotordynamics design calculations, we have been developing a tracking solver based upon the sliding mode control. Our solver can continuously follow the varying behavior of the characteristic root of dynamical systems caused by a parameter change. By assuming the bearing stiffness or the rotational speed as the time parameter t, the solva provide characteristic root λ(t). This solving method is successfully applied to characteristic polynomial equations of M-K-C systems and the transfer matrix systems. In this paper, the overview of this method produced a rather sophisticated modification which is similar to a car following an exact track by steering control. This modified solver, using sliding mode controlled steering is again applied to rotordynamics design calculations. Compared with the conventional solver, this new solver can track the rather complex behaviors of the varying solution. The effectiveness is demonstrated by several cases; non-linear response curves, critical speed map and eigenvalue locus of a 3 disc rotor supported by oil-film bearings.
