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