Low-Voltage Closed Loop MEMS Actuators

An efficient electrostatic resonator is designed by adding a low voltage controller to an electrostatic actuator. The closedloop actuator shows stable, and bi-sable behaviors with bounded chaotic oscillations as large as 117% of the capacitor gap. The controller voltage is decreased from a previously designed resonator to less than 9 V thereby reducing the load on the controller circuit components. Bifurcation diagrams are obtained showing the frequency and magnitude of AC voltage required for chaotic oscillations to develop. The information entropy, a measure of chaotic characteristic, is calculated for the micro-resonator and is found to be 0.732

A Large-Stroke Electrostatic Micro-Actuator

Voltage-driven parallel-plate electrostatic actuators suffer from an operation range limit of 30% of the electrostatic gap; this has restrained their application in microelectromechanical systems. In this paper, the travel range of an electrostatic actuator made of a micro-cantilever beam above a fixed electrode is extended quasi-statically to 90% of the capacitor gap by introducing a voltage regulator (controller) circuit designed for low-frequency actuation. The voltage regulator reduces the actuator input voltage, and therefore the electrostatic force, as the beam approaches the fixed electrode so that balance is maintained between the mechanical restoring force and the electrostatic force. The low-frequency actuator also shows evidence of high-order superharmonic resonances that are observed here for the first time in electrostatic actuators

Dynamics of a Close-Loop Controlled MEMS Resonator

The dynamics of a close-loop electrostatic MEMS resonator, proposed as a platform for ultra sensitive mass sensors, is investigated. The parameter space of the resonator actuation voltage is investigated to determine the optimal operating regions. Bifurcation diagrams of the resonator response are obtained at five different actuation voltage levels. The resonator exhibits bi-stability with two coexisting stable equilibrium points located inside a lower and an upper potential wells. Steady-state chaotic attractors develop inside each of the potential wells and around both wells. The optimal region in the parameter space for mass sensing purposes is determined. In that region, steady-state chaotic attractors develop and spend most of the time in the safe lower well while occasionally visiting the upper well. The robustness of the chaotic attractors in that region is demonstrated by studying their basins of attraction. Further, regions of large dynamic amplification are also identified in the parameter space. In these regions, the resonator can be used as an efficient long-stroke actuator

Dynamics of a close-loop controlled MEMS resonator

The dynamics of a close-loop electrostatic MEMS resonator, proposed as a platform for ultra sensitive mass sensors, is investigated. The parameter space of the resonator actuation voltage is investigated to determine the optimal operating regions. Bifurcation diagrams of the resonator response are obtained at five different actuation voltage levels. The resonator exhibits bi-stability with two coexisting stable equilibrium points located inside a lower and an upper potential wells. Steady-state chaotic attractors develop inside each of the potential wells and around both wells. The optimal region in the parameter space for mass sensing purposes is determined. In that region, steady-state chaotic attractors develop and spend most of the time in the safe lower well while occasionally visiting the upper well. The robustness of the chaotic attractors in that region is demonstrated by studying their basins of attraction. Further, regions of large dynamic amplification are also identified in the parameter space. In these regions, the resonator can be used as an efficient long-stroke actuator

Scaling Laws for Linear Controllers of Flexible Link Manipulators Characterized by Nondimensional Groups

When constructing large robotic manipulators or space structures, it is advisable to begin with a small-scale prototype on which to perform the design, analysis, and debugging. To ensure that the results obtained on the scalemodel apply directly to the actual manipulator, it is necessary that the prototype and the original robot are dynamically equivalent. As an initial investigation, this paper examines the single flexible link (SFL) manipulator. Dimensional analysis is used to identify the nondimensional groups for the SFL. These groups are present in the corresponding nondimensional equations of motion, which are also derived. To account for inherent manufacturing imprecision, tolerances are developed for the nondimensional groups. Scaling laws for continuous-time and discrete-time controllers are developed for dynamically equivalent SFL systems. These theoretical scaling laws are verified experimentally for an H1 and a PD control strategy. I. Introduction A common shortfall in..

Nonlinear Parameter Identification of a Resonant Electrostatic MEMS Actuator

We experimentally investigate the primary superharmonic of order two and subharmonic of order one-half resonances of an electrostatic MEMS actuator under direct excitation. We identify the parameters of a one degree of freedom (1-DOF) generalized Duffing oscillator model representing it. The experiments were conducted in soft vacuum to reduce squeeze-film damping, and the actuator response was measured optically using a laser vibrometer. The predictions of the identified model were found to be in close agreement with the experimental results. We also identified the noise spectral density of process (actuation voltage) and measurement noise