Adaptive Nonlinear Control of SMA-Based Bending Micro Actuator

Shape Memory Alloys (SMAs) have several attractive features that make them potentially useful concepts as bending micro actuators. SMA linear actuators are among those producing the highest strains and highest forces available, and when employed in a bending mode, their deflection capability is enhanced even more leading to potential new applications. This paper addresses the basic design concept for a bi-material actuator modeled as an initially curved composite beam with one active layer, the SMA material, and one conventional elastic layer. This device must be accurately controlled to achieve an optimal range of motion and to serve in many new applications so we have designed a nonlinear and adaptive control scheme based on Lypaunove stability theory to prevent erratic motion and even component separation and partial buckling. In addition, this control scheme is able to achieve high precision tracking without the need for detailed system parameters. Simulation is conducted which confirm the effectiveness of the proposed method.Copyright © 2008 by ASME