NONLINEAR OPEN LOOP OPTIMAL TRACKING USING MAGNETOSTRICTIVE TRANSDUCERS

The design of high performance smart material devices requires control laws that can achieve stringent performance criteria required in many industrial, automotive, aerospace and biomedical applications. Moderate to high field inputs are often required which introduces nonlinear, hysteretic constitutive behavior. This often cannot be effectively compensated using linear control theory. In the present work, a nonlinear optimal control methodology is developed for tracking a reference trajectory when nonlinear, hysteretic constitutive behavior is significant. For brevity, we focus on open loop control for regimes when disturbances are minimal. The nonlinear control design is investigated on magnetostrictive rod-type actuators by implementing a homogenized energy model. Significant emphasis is place on material behavior at multiple length scales to produce an accurate and efficient model to compensate for nonlinear, hysteretic magnetostrictive constitutive behavior.