An Enhanced Dynamic Model for the Actuator/Amplifier Pair in AMB Systems

Typical models for AMB actuators consist of a static linearized mapping from displacement and current to (orce (f ~ -K",x + Kd) and are augmented with actuator dynamics (bandwidth and gain) which act to correlate a command signal Vc to resulting current: 1(8) = Ga(s)Vc(s). In the present work, we show that this model misses a number of potentially important features, most notably the effect of amplifier bandwidth limitations on the term mapping displacement to force (K",) and the related influence of journal motion induced back-EMF. In addition, we show how actuator eddy currents intact with the amplifier dynamics and how to model the resulting composite system.