Impact dynamics of micromachined bidirectional electrothermal vibromotors

Abstract

The motion of micromachined bidirectional electrothermal vibromotors (BETV) is analyzed using an impact model that takes into account friction and contact, as well as the compliance of the slider and the impact head. This model addresses several important issues on the usage of BETV. These include (a) how to achieve the pull and push mode; (b) avoiding multiple impacts in one actuation cycle; (c) the existence of periodic solutions with the same period as the thermal actuator. Four dimensionless parameters are found to govern the dynamics of the vibromotor. Depending on these parameters, we observed periodic motion, period doubling, and aperiodic solution. A criterion is established to separate push and pull modes. An experiment that includes fabricating and characterizing a BETV is carried out to verify the ability of the model to predict the pull mode.