Improved model of rectangular scratch drive actuator

This paper proposes an integrated model of a scratch drive actuator (SDA) based on a fourth-order governing equation of the Euler-Bernoulli theory. By solving this equation with proper boundary conditions, typical SDA output characteristics, such as noncontact length, priming voltage, deflection curve, output force, and bending stress, can be determined. The results of the output force in a static model are then used as the input of single degree-of-freedom dynamic SDA model to investigate the friction effect. Electroplated nickel SDA arrays, 80 m in main beam length and 65 m in width with a suspended spring, are fabricated and tested. The average travel distances after 1500 input pulses of 80-120 V are measured and found to be from 4.7 to 12.9 m. The average measured output forces are from 10.2 to 28.3 μN. The simulation from the dynamic model is closer to the measured total travel distance and the output force than the static model, in general. The difference between simulations and experimental data due to energy dissipation can be reduced by including the friction effect in the dynamic model. Deviations between simulations and measured results are less than 10 in full range showing the superior capability of the proposed SDA model.