CONTROL OF TERFENOL-D UNDER LOAD

A vibration control case study is described which demonstrates the app lication of magnetostrictive (Terfenol-D) actuators. The magnetomechan ical properties of the material suggests that when incorporated in dev ices for applications a nonlinear response will result. This case stud y compares the performance of two kinds of control strategy (both disc rete), a conventional proportional and integral (PI) algorithm and a v ariable structure algorithm (DVSC) in both servo and cancellation/regu lation roles. Both strategies were implemented on an INMOS(7) transput er based microcontroller with a sampling period of 300 mu s. The resul ts presented show that the control behavior of the DVSC strategy offer s significant advantages over the PI strategy when controlling actuato rs with nonlinear characteristics, i.e., the rejection of a 5 Hz distu rbance with a gain of -36 dB compared to a gain of -15 dB when using t he PI strategy.