Modeling and Optimal Low-Power On–Off Control of Thin-Film Piezoelectric Rotational Actuators

Edamana, Biju; Hahn, Byung‐Dong; Pulskamp, Jeffrey S.; Polcawich, Ronald G.; Oldham, Kenn R.

doi:10.1109/tmech.2010.2053041

Cited by 19 publications

(10 citation statements)

References 20 publications

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“…on-off or PWM) is typically much greater than that of analog circuits at high voltages. For instance, small capacitive loads encountered in piezoelectric micro-actuation are known to consume as much as 95% more energy in analog amplifiers than is used by the load [40], [41]. …”

Section: Discussionmentioning

confidence: 99%

Modeling and Simulation of a Parametrically Resonant Micromirror With Duty-Cycled Excitation

Qiu

Duan

et al. 2014

J. Microelectromech. Syst.

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High frequency large scanning angle electrostatically actuated microelectromechanical systems (MEMS) mirrors are used in a variety of applications involving fast optical scanning. A 1-D parametrically resonant torsional micromirror for use in biomedical imaging is analyzed here with respect to operation by duty-cycled square waves. Duty-cycled square wave excitation can have significant advantages for practical mirror regulation and/or control. The mirror’s nonlinear dynamics under such excitation is analyzed in a Hill’s equation form. This form is used to predict stability regions (the voltage-frequency relationship) of parametric resonance behavior over large scanning angles using iterative approximations for nonlinear capacitance behavior of the mirror. Numerical simulations are also performed to obtain the mirror’s frequency response over several voltages for various duty cycles. Frequency sweeps, stability results, and duty cycle trends from both analytical and simulation methods are compared with experimental results. Both analytical models and simulations show good agreement with experimental results over the range of duty cycled excitations tested. This paper discusses the implications of changing amplitude and phase with duty cycle for robust open-loop operation and future closed-loop operating strategies.

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Section: Discussionmentioning

confidence: 99%

Modeling and Simulation of a Parametrically Resonant Micromirror With Duty-Cycled Excitation

Qiu

Duan

et al. 2014

J. Microelectromech. Syst.

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“…The objective function in this case can be written as (17) where u(i) ∈ 0, 1 are binary. Techniques for solving this problem were described in [1].…”

Section: Solution Strategymentioning

confidence: 99%

“…Since the energy consumed for one charging of the actuator is 1 2 Cu 2 max and nearly all energy used by a piezoelectric actuator is consumed when it charges, this objective acts to minimize the number of chargings and dischargings in the actuator array. The constraints for the optimization are the deterministic part of the dynamics equations given in (1). A Monte Carlo study was done to document the advantages of this modification on the energy consumption.…”

Section: And Cross Covariance Betweenmentioning

confidence: 99%

“…The chief application for optimizing finite duration ON-OFF control inputs was evaluation of autonomous walking microrobot feasibility, with ON-OFF inputs intended to produce a quasi-static walking gait by controlling rotational motions of microrobotic leg joints driven by piezoelectric actuators. During each step, actuators may be rotated to prescribed angles in a prescribed time using minimum energy by solving an integer programming problem; the resulting ON-OFF inputs minimize the number of times the actuator is turned ON while staying within a specified bound on final position error [1]. This previous work done by the authors is an alternative to existing control strategies for piezoelectric actuators proposed earlier by Main et al [2] and Campolo et al [3].…”

Section: Introductionmentioning

confidence: 99%

“…As a frame of reference, capacitances of the proposed thin-film lead-zirconate-titanate microactuators for microrobotics are often on the order of 0.1-1 nF [4]. In [1], the authors proposed use of optimal ON-OFF control strategies requiring nominally 40-400 nJ per charge/discharge cycle at 20 V. In comparison, state-of-the-art commercial low-power capacitive sensing circuits with A/D conversion require the equivalent of about 500 nJ per sample acquisition (50 μW for 100 samples/s [5]), and piezoresistors at this scale would need to be operated at less than 2% duty cycle to achieve comparable energy consumption. Similar sensing circuit power consumption was reported in [6] and [7].…”

Section: Introductionmentioning

confidence: 99%

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A Near-Optimal Sensor Scheduling Strategy for an on–off Controller With an Expensive Sensor

Edamana

Oldham

2014

IEEE/ASME Trans. Mechatron.

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This paper describes an efficient method for scheduling an energy-consuming sensor sparingly in combination with an ON-OFF controller, specifically for a finite horizon control problem in which only end states are critical. In certain low-power applications, such as autonomous microrobotics, ON-OFF controllers can be very efficient in operating piezoelectric actuators (and other capacitive actuation schemes) compared to traditional analog and pulsewidth modulation controllers. However, with existing sensing circuitry, sensing at the same frequency as control can be prohibitively expensive, because energy consumption in the sensing circuitry may be comparable or even much higher than energy consumption for actuation. Instead, a method is presented for best scheduling a limited number of sensor measurements and updates to control inputs during a finite horizon ON-OFF control problem, in response to Gaussian disturbances and measurement noise. To simplify the problem, a lower bound for the expected value of a quadratic error function of the end states is found, which permits rapid evaluation of candidate sensor times. When actuator energy consumption is incorporated in the optimization, this produces a numerically efficient near-optimal strategy for determining best measurement times and updates to the control input sequence.

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On‐off iterative adaptive controller for low‐power micro‐robotic step regulation

Hahn

Oldham

2011

Asian Journal of Control

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A novel model-free iterative adaptive controller is presented for lowpower control of piezoelectric actuators. The controller uses simple adaptation rules based on known general behavior of piezoelectric actuators to adjust onoff switching times to drive piezoelectric actuators through a desired transient step motion. Adaptation rules are based on small numbers of measurements taken during each iteration of the actuator movement. Combined with the use of only on-off control inputs, controller implementation can be possible at much lower overall power levels than would be needed to implement a conventional control strategy such as through pulse-width-modulation (PWM) with real-time feedback. Such power savings are particularly important for the intended controller application to piezoelectric microactuators driving autonomous terrestrial micro-robots. A method for predicting convergence of systems with nominally linear dynamics and unknown, bounded nonlinearities is described, and applied to a sample target piezoelectric actuator. The controller is tested in simulation and experimentally on a piezoelectric cantilever actuator, and shows predicted convergence to the desired response.

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Modeling and Optimal Low-Power On–Off Control of Thin-Film Piezoelectric Rotational Actuators

Cited by 19 publications

References 20 publications

Modeling and Simulation of a Parametrically Resonant Micromirror With Duty-Cycled Excitation

Modeling and Simulation of a Parametrically Resonant Micromirror With Duty-Cycled Excitation

A Near-Optimal Sensor Scheduling Strategy for an on–off Controller With an Expensive Sensor

On‐off iterative adaptive controller for low‐power micro‐robotic step regulation

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