In recent years, active magnetic bearing systems (AMBs) have attracted the
attention of researchers as suitable replacements for conventional mechanical and
hydrostatic bearings. The absence of mechanical frictions, high-precision and low
maintenance costs have all made AMBs suitable technologies for high-speed and
high-precision applications. However, along with the numerous advantages, several
challenges have hindered the widespread applications of these systems. AMBs
are inherently open-loop unstable and hence feedback controllers are essential for
stabilisation of AMB equipped systems. The multiple-input multiple-output nature
of AMBs and the presence of high-frequency resonant modes further exacerbate
the problem of modelling and control design of such systems.