Computation of inverse of magnetostriction model for Terfenol-D

The use of a non-linear model or non-linear inverse model in a control conf iguration has been shown to significantly improve the performance of actuat ors that use hysteretic materials to drive them. A method to calculate the inverse of a model for the hysteretic material Terfenol-D is presented here , to be used as part of a full control configuration for Terfenol-D actuato rs. This inverse is based on a magnetostriction model that has been shown t o characterize the behavior of Terfenol-D well. Initially unbounded, accumu lating errors in the inverse are analyzed and a method to bound the error f or periodic input is presented. Simulations show steady-state tracking of s train waveforms that reach 95% of saturation to within 2% in an open-loop c onfiguration. For use with inputs as high as 95% of saturation, though, the ratio of the input frequency to the sampling rate must be kept below speci fied levels. With inputs that reach only 85% of saturation, the error from inversion is below 0.2% and can be controlled by a parameter choice. (C) 20 00 Elsevier Science B.V. All rights reserved.