EXPERIMENTAL EVALUATION OF H-INFINITY CONTROL FOR A FLEXIBLE BEAM MAGNETIC SUSPENSION SYSTEM

An H(infinity) robust controller is experimentally demonstrated on a magnetic suspension system with a flexible beam. The experiment apparatus utilized in this study is a simplified model of magnetic bearings with an elastic rotor. We first derive a suitable mathematical model of the plant by taking account of various model uncertainties. Next we setup the standard problem, where the generalized plant is constructed with frequency weighting functions. An iterative computing environment MATLAB is then employed to calculate the central controller. The techniques devised for the selection of design parameters involve both the game theoretic characterizations of the central controller in the time domain and the all-pass property of the closed loop transfer function in the frequency domain. Finally, the digital controller is implemented using a DSP muPD77230 where the control algorithm is written in the assembly language. Several experiments are carried out in order to evaluate the robustness and the performance of this H(infinity) design. These experimental results confirm us that the flexible beam magnetic suspension system is robustly stable against various real parameter changes and uncertainties.