Dynamic Modeling of Scratch Drive Actuators

There has been much research in developing scratch drive actuators (SDAs), but because of their dynamic complexity, these microelectromechanical system-based actuators have not been dynamically analyzed up to now. In this paper, a comprehensive model is presented to describe the dynamic behavior of SDA and its components during stepwise motion. In this model, Hamilton´s principle and Newton´s method are used to extract dynamic equations of the SDA plate and dynamic equation for the linear motion of SDA. This model presents a good insight into the operating principles of SDA by predicting the variation of different variables, such as bushing angle, contact length, horizontal position, and friction forces, during the application of different voltage profiles. Comparison between the modeling results and the available experimental data shows that this model is very effective in predicting some design objectives, such as step size and output force, for these type of actuators.