closed loop systems, compensation, control system synthesis, frequency estimation, frequency-domain analysis, magnetic bearings, notch filters, real-time systems, MATLAB, MBC 500,  axial channel stabilisation, frequency domain data, lead compensators, phase margin, re-engineering controllers, real-time implementation, resonant frequencies, resonant modes, system identification, system stability, control system synthesis, control systems, filters, magnetic levitation, magnetic resonance, magnetic separation, mathematical models, system identification