The stable operating region of an electrostatic comb drive actuator in constant-gap mode is limited by a subcritical pitch-fork bifurcation known as side pull-in. We show that oscillatory open-loop control can forestall side pull-in and substantially extend the stable operating region. To our knowledge, this is the first demonstration of control of side pull-in without additional lateral actuators. To our knowledge it is also the first application of open-loop oscillatory control to an electrostatic MEMS model using a single control voltage. Simulations show the stable range of travel increased by over 60%, with an associated oscillation of less than 2%. Although feedback control has been used to stabilize a related bifurcation in electrostatic gap-closing actuators, we show that these approaches are unlikely to succeed for side pull-in. Finally, we present and validate formulas relating parameters of the oscillatory input to the average value and oscillations of the resulting displacement.
- Dynamic Systems and Control Division
Stabilization of the Side Pull-In Bifurcation of an Electrostatic Comb Drive Actuator Model Using Oscillatory Open-Loop Control
Wickramasinghe, IPM, & Berg, JM. "Stabilization of the Side Pull-In Bifurcation of an Electrostatic Comb Drive Actuator Model Using Oscillatory Open-Loop Control." Proceedings of the ASME 2011 Dynamic Systems and Control Conference and Bath/ASME Symposium on Fluid Power and Motion Control. ASME 2011 Dynamic Systems and Control Conference and Bath/ASME Symposium on Fluid Power and Motion Control, Volume 1. Arlington, Virginia, USA. October 31–November 2, 2011. pp. 771-778. ASME. https://doi.org/10.1115/DSCC2011-6176
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