Research Introduction Lab of Smart Structures 精密机械与精密仪器系 Precision Machinery and...

Research Introduction

Lab of Smart Structures

精密机械与精密仪器系 Precision Machinery and Precision Instrumentation

Contents

精密机械与精密仪器系 Precision Machinery and Precision Instrumentation

4. Energy harvesting

3. Precision control of piezoelectric actuators

2. Piezoelectric transformers

1. Smart piezoelectric actuators

5.Other researches

1. Small Piezoelectric Actuators

a. Fiber torsional actuator b. Tube actuators and its composite

discovery

a. Discovery of torsional actuation a. Discovery of torsional actuation

Test setup

Static response of voltage

Dynamic response of frequencyC. L. Pan, Z. H. Feng, et al., "Small torsional piezoelectric fiber actuators with helical electrodes,“ Applied Physics Letters, vol. 92, p. 012923, 2008.

Resonance image of the prototype actuator’s free end.Resonance image of the prototype actuator’s free end.

Experimental measurement

Experimental measurement

Piezoelectric fiber motor Bulk piezo cylinder moter

Application—Impact piezoelectric motorApplication—Impact piezoelectric motor

RotorRotor

Impact response of the fiber motor Impact response of the bulk motor

W. X. Han, Z. H. Feng, et al., "An impact rotary motor based on a fiber torsional piezoelectric actuator," Review of Scientific Instruments, vol. 80, p. 014701, 2009.

Impact piezoelectric motorImpact piezoelectric motor

Impact piezoelectric motor

For a 15 mm length fiber:

Torsional vibration, 0-30 kHz bandwidth, 0.2° amplitude

Longitudinal vibration, 0-50 kHz bandwidth, 1 μm amplitude

It consists of cantilevers, hinges, and mirror.

It consists of cantilevers, hinges, and mirror.Designed structureDesigned structure

Miniature optical scanning mirror

Principle of 2-D scanning

Fabrication and test

C. L. Pan, Z. H. Feng, et al., "Miniature orthogonal optical scanning mirror excited by torsional piezoelectric fiber actuator," Sensors and Actuators A: Physical, vol. 165, pp. 329-337, 2011.

Measured vertical frequency response of the prototype scanners.

Measured vertical frequency response of the prototype scanners.

Results

SPM: Scanning Probe Microscopy

AFM: Atomic Force Microscope AFM: Atomic Force Microscope

Voltage driving for getting x direction displacement

Voltage driving for getting x direction displacement

Side view and top view of a piezoelectric tubeSide view and top view of a piezoelectric tube

b. Piezoelectric scanners used in SPM

Piezoelectric tubes with film electrodes on their outer and inner surfaces can be used to compose multitube actuators. The actuator of four piezoelectric tubes can substitute the traditional single-tube actuator.

Piezoelectric tubes with film electrodes on their outer and inner surfaces can be used to compose multitube actuators. The actuator of four piezoelectric tubes can substitute the traditional single-tube actuator.

(a) single-tube actuator, (b) four-tube actuator.(a) single-tube actuator, (b) four-tube actuator.

Advantages:1.Much more accurate actuation can be achieved by deliberate arrangement of the four tubes.

2. Multitube structure has better performances under certain conditions.

Advantages:1.Much more accurate actuation can be achieved by deliberate arrangement of the four tubes.

2. Multitube structure has better performances under certain conditions.

Multitube actuatorsMultitube actuators

The end surface of the four-tube actuator.The end surface of the four-tube actuator. The trace of a distinct point on the actuator’s moving head.

The trace of a distinct point on the actuator’s moving head.

ExperimentsExperiments

Miniature tubular centrifugal piezoelectric pump

The structure of the centrifugal pump using wobbling motion of a metal tube to push the liquid out.

(a) The mechanical structure of a prototype pump. (b) The photograph of the prototype pump.

Y. T. Ma, Z. H. Feng, et al., "Miniature tubular centrifugal piezoelectric pump utilizing wobbling motion,“ Sensors and Actuators A: Physical, vol. 157, pp. 322-327, 2010.

精密机械与精密仪器系 Precision Machinery and Precision Instrumentation

Experimental measurement

Flow rate at different driving frequencies, under 120Vp-p driving voltage and 2.0 kPa backpressure. A maximum flow rate of 7.7ml/min

occurs at 232Hz. 。

120Vp-p

2.0kPa

233.2Hz

The relationship between the flowrate and backpressure at different driving voltages shows a good linearity.

Structure of the stator:

Structure of the prototype motor:

Stiffness2.5N/mm

(a)dimensions of the stator (b) stator settled on the base. (a)Sectional drawing

(b) external appearance.

Two-Phase Piezoelectric Motor

Angular speed, output power, and efficiency versus loadAngular speed versus driving voltage amplitude.

Experimental measurement result

Y. T. Ma, Z. H. Feng, et al., "Two-Phase Piezoelectric Motor Using a Multiple-Tube Structure actuator,“ Japanese Journal of Applied Physics, vol. 48, Sep 2009.

2. Piezoelectric Transformer

Radiator heightens power density of piezoelectric transformers

For a specific PZT-5H sample considered, this material can handle 330 W/cm3 at 100 kHz in theory. However, the maximum output power density of current PTs is typically less than 30 W/cm3

W. W. Shao, Z. H. Feng, et al., "Radiator heightens power density of piezoelectric transformers,“ Electronics Letters, vol. 46, p. 1662, 2010.

Construction and dimensions of proposed piezoelectric transformer operating in contour-extensional vibration mode

Construction and dimensions of proposed piezoelectric transformer operating in contour-extensional vibration mode

Photograph of the prototype device

PT:

Roughness Ra 0.2 μm. copper plate ： Dimensions ： 32×25×1 mm3

Roughness Ra of 0.02 μm A layer of grease pad

thickness 0.23 mm

insulation and transfer heat. A spring with a stiffness of 1 N/mm is attached to a bolt ； a thread pitch of 0.5 mm to supply variable pressing force .

Results of test

Based on this research, it is hoped to make metal-cased piezoelectric transformers, which will have wide application potential in many fields.

When the input voltage increased to 150 Vpp, the temperature rise of the free PT increased rapidly over 30 ºC and then continued up to a higher value.

The characteristics of PT became quite unstable.

3. Precision Control of Piezoelectric Actuators

Charge pump controller

Hysteresis of piezoelectric actuators

Piezoelectric actuators hysteresis Configuration of the voltage amplifier Configuration of the voltage amplifier

Configuration of the charge amplifier Configuration of the charge amplifier

精密机械与精密仪器系 Precision Machinery and Precision Instrumentation

Switched capacitor charge pump reduces hysteresis

Principle of switched charge pumpPiezoelectric actuators hysteresisPiezoelectric actuators hysteresis

Floating groundFloating ground

精密机械与精密仪器系 Precision Machinery and Precision Instrumentation

Experimental setup

control with small steps. control with small steps.

Displacement step is 15 nmDisplacement step is 15 nm

control with large steps control with large steps

Displacement resonance of piezoelectric stack

Displacement resonance of piezoelectric stack

精密机械与精密仪器系 Precision Machinery and Precision Instrumentation

The hysteresis of the voltage and charge drive

Cha

rge

Vol

tage

The result of the three control methods

0.02Hz 0.1Hz 0.5Hz 1Hz 5Hz 20Hz

Voltage 8.15% 8.17% 8.41% 9.21% 10.5% 10.8%

Charge 9.37% 9.19% 7.16% 4.21% 0.2% 4.65%

Switch 1.84% 1.55% 1.47% 1.13% 0.72% 0.71%

L. Huang, Z. H. Feng, et al., "Switched capacitor charge pump reduces hysteresis of piezoelectric actuators over a large frequency range," Review of Scientific Instruments, vol. 81, p. 094701, 2010.

Charge pump controller for grounded piezoelectric actuators

Charge pump controller for grounded piezoelectric actuators

Schematic charge pump controller for the grounded loadSchematic charge pump controller for the grounded load

4. Energy Harvesting

Maximum mechanical energy harvesting strategy for a piezoelement

Proposed energy harvesting system using a piezoelectric element.

Standard circuit for energy harvesting

W. Q. Liu, Z. H. Feng, et al., "Maximum mechanical energy harvesting strategy for a piezoelement," Smart Materials and Structures, vol. 16, pp. 2130-2136, 2007.

For a fixed material and structure, the system would exhibit a better performance following the use of the control method suggested. This will greatly improve the design of the power generator.

For a fixed material and structure, the system would exhibit a better performance following the use of the control method suggested. This will greatly improve the design of the power generator.

Analytical process Analytical process

Proposed cycle for output maximum energy Proposed cycle for output maximum energy

精密机械与精密仪器系 Precision Machinery and Precision Instrumentation

Right-angle piezoelectric cantilever

Right-angle cantilever uniform strain distribution of piezoelement

Right-angle cantilever uniform strain distribution of piezoelement

Strain distribution in the surface of PZT elementduring vibration.

Frequency response for the two devices at sinusoidalvibration amplitude of 2.5 m s−2

.

Results of test

It has been determined that the competenceof the right-angle cantilever for energy harvesting under a

strain limit is 2 times larger than that of the traditionalcantilever. The right-angle cantilever system produces more

electrical energy compared to a traditional cantilever.

J. W. Xu, Z. H. Feng, et al., "Right-angle piezoelectric cantilever with improved energy harvesting efficiency," Applied Physics Letters, vol. 96, p. 152904, 2010.

精密机械与精密仪器系 Precision Machinery and Precision Instrumentation

Outline drawing of the wind-energy-harvesting device.

Piezoelectric Wind-Energy-Harvesting Device with Reed and Resonant Cavity

Equivalent circuit

The relationships between output power, the load resistance, and the wind speed.

Output power and the energy conversion efficiency with a resistive load 0.46MΩ

J. Ji, Z. H. Feng, et al., "Piezoelectric Wind-Energy-Harvesting Device with Reed and Resonant Cavity," Japanese Journal of Applied Physics, vol. 49, p. 050204, 2010.

Results of testThe device was investigated with a wind speed ranging

from 2.8 to 10m/s. An output power of 0.5–4.5mW was obtained with a matching load of 0.46MΩ. The energy conversion

efficiency of the device could reach up to 2.4%.

5. Other Researches

The equivalent circuit of a piezoelectric sensor linked with a voltage amplifier.The equivalent circuit of a piezoelectric sensor linked with a voltage amplifier.

The equivalent circuit of a piezoelectric element linked with a charge amplifier.The equivalent circuit of a piezoelectric element linked with a charge amplifier.

Signal Conditioning Methods for Piezoelectric Sensors

Signal Conditioning Methods for Piezoelectric Sensors

W. Q. Liu, Z. H. Feng, et al., "The influence of preamplifiers on the piezoelectric sensor’s dynamic property," Review of Scientific Instruments, vol. 78, p. 125107, 2007.

Experimental setup.

The influence of preamplifiers on the piezoelectric sensor’s dynamic property

A High-sensitive Static Vector Magnetometer based on 2D vibration

A High-sensitive Static Vector Magnetometer based on 2D vibration

Schematic diagram of device configuration Schematic diagram of device configurationReflection method to measure vibration angle Reflection method to measure vibration angle

Tw

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ibra

ting

Co

ilsT

wo

Vib

ratin

g C

oils

The linear range is about 100 μT, which is available in

earth magnet detection, navigation, vehicle detection and so on.

The linear range is about 100 μT, which is available in

earth magnet detection, navigation, vehicle detection and so on.

Science

High-speed Electrically

Actuated Elastomer

High-speed Electrically

Actuated Elastomer

精密机械与精密仪器系 Precision Machinery and Precision Instrumentation