Control of Terfenol‐D under load

A vibration control case study is described which demonstrates the application of magnetostrictive (Terfenol‐D) actuators. The magnetomechanical properties of the material suggests that when incorporated in devices for applications a nonlinear response will result. This case study compares the performance of two kinds of control strategy (both discrete), a conventional proportional and integral (PI) algorithm and a variable structure algorithm (DVSC) in both servo and cancellation/regulation roles. Both strategies were implemented on an INMOS transputer based microcontroller with a sampling period of 300 μs. The results presented show that the control behavior of the DVSC strategy offers significant advantages over the PI strategy when controlling actuators with nonlinear characteristics, i.e., the rejection of a 5 Hz disturbance with a gain of −36 dB compared to a gain of −15 dB when using the PI strategy.