Modeling and Analytical Study of Scratch Drive Actuators

This paper presents a new analytical model of Scratch Driver Actuator (SDA) to obtain the design parameters of this device. In order to simulate working states of the SDA, three different static modes are considered: non-contact mode, transition mode, and full-contact mode. The SDA is simplified as an L-shape beam with different boundary conditions in each mode. Using beam theories in bending, the governing equation is derived and solved in each mode. The non-contact mode allows identifying the deflection and the driving voltage after which the actuator plate starts touching the substrate. From the transition mode, we calculate the primary contact length to be used for the analysis of the full-contact mode. In the full-contact mode, the SDA is completely snapped down in its working cycle. From this mode, we obtain the relationships between input voltage and design parameters such as SDA geometry, contact length, and step size. It is shown that a good agreement between theoretical results and experimental values is achieved, which verifies the validity of the new model.Copyright © 2006 by ASME