Experimental characterization and modeling of rate-dependent asymmetric hysteresis of magnetostrictive actuators

The hysteresis nonlinearities of a magnetostrictive actuator were characterized under different amplitudes of simple and complex harmonic excitations over a wide range of frequencies (10-200 Hz) and magnetic bias levels (35-75 kA m(-1)). The measured data revealed asymmetric output-input characteristics and strong dependence on the magnetic bias, amplitude and frequency of the input. Output saturation was also observed under moderate to high amplitude excitations. A phenomenological hysteresis model is proposed in this study to model the hysteresis nonlinearities of a magnetostrictive actuator. A rate-dependent Prandtl-Ishlinskii model integrating a memoryless function of deadband operator was subsequently formulated to describe both the rate dependence and the asymmetric hysteresis loops of the magnetostrictive actuator in addition to the output saturation. Comparisons of the integrated Prandtl-Ishlinskii model responses with the measured data suggested that the model can effectively describe the nonlinear hysteresis properties of the magnetostrictive actuator over a broad range of excitation amplitudes and frequencies. The inverse of the proposed rate-dependent Prandtl-Ishlinskii model can be obtained analytically. Then, the inverse model can be applied as feedforward compensator for compensation of asymmetric rate-dependent hysteresis nonlinearities without using feedback control techniques.