Nonlinear Perturbation Control for Magnetic Transducers

Stringent performance criteria often required in many smart material applications necessitates the need for robust control designs. Moderate to large field inputs typically introduce nonlinear, hysteretic constitutive behavior which degrades performance when linear control theory is implemented. In this paper, a hybrid nonlinear optimal control design is numerically implemented on a Terfenol-D magnetostrictive actuator to track a reference trajectory in operating regimes where nonlinear, hysteretic constitutive behavior is present. The control design incorporates perturbation feedback around an optimal open loop trajectory. The optimal open loop trajectory is computed off-line using a homogenized energy model to predict nonlinear and hysteretic constitutive behavior. The perturbation feedback is implemented using classic proportional-integral (PI) control to improve robustness to operating uncertainties. The hybrid nonlinear control design is compared to classic PI control to illustrate where improvements are achieved