Transcript 2.2 Input voltage wave form of pulse

Lab. Of Intelligent Material and Technology
Excitation of an Asymmetric Displacement without
Residual Vibration and its Application to Construct
a Piezoelectric Actuator
이명호
Abstract
• This paper deals with a new excitation method of a
piezoelectric actuator in order to achieve its asymmetric
displacement as a function of time elapsed without its
residual vibration : The method is to use the rectangular
pulse of voltage and is aimed to develop a new type
piezoelectric actuator with a function of a both direction
operation.
Analysis on displacement of such an actuator driven by
the rectangular pulse, and proposal of its application to
concrete actuators with its experimental description are
reported.
Introduction
• A piezoelectric actuator is one of attractive devices in the modern
engineering, due to its inherent multi-functions and small
construction. its quick response
• Electrical pulse driving was considered to prevent the mechanical
residual vibration of the actuator.
• The prevention of residual vibration succeeds to a quick response of
the actuator.
• This asymmetric operation of an actuator can be variously applied,
for example, to construct a part-feeder, a linear movement-device
and a rotary one.
• In the first part of this paper are described some responses of a
piezoelectric actuator by input voltage wave form of pulse.
• The second part contains applications of such actuators and
experimental results on them.
2.1 A piezoelectric actuator and its equivalent circuit
• Fig. 1(a) is only a representative of general piezoelectric actuator.
• The lowest response of vibration is dominant for actuator operations,
even if the actuator has many responses.
• There are such following correspondences that motional current
q˙m(t) and electric charge qm(t) are equal to a speed of vibration
and a displacement, respectively, at a certain point of the actuator .
• By analyzing q˙m(t) and qm(t) in the equivalent circuit when the input
voltage wave form of pulse in fig. 1(b) is supplied, vibrational
characteristics of the actuator can obtained.
2.2 Input voltage wave form of pulse
• In order to achieve a sharp rising-up
displacement of the actuator, such rectangular
pulse as shown in figure is first applied and in
the next step, after a somewhat interval, the
voltage goes down slowly.
• By such asymmetric voltage wave form , we
expect, the asymmetric operation of an actuator
can be made possible.
2.2 Input voltage wave form of pulse
2.2 Input voltage wave form of pulse
• From these results, it is found that
actuator displacement responses of
a sharply rising-up and gently
sloping-down characteristic can
easily obtained and the form of
characteristic is differently changed
by input voltage wave form.
• A specific feature of the
characteristic appears at the
condition (B-N)≥2.0 ; that is,
one or tow plateaus
are yielded in the gently sloping-down part.
2.2 Input voltage wave form of pulse
• The characteristic shown in
fig.5 is one example to
the wave form of pulse
shown in Fig. 2(b)
• We say in addition that the input
voltage wave form of pulse
shown in Fig. 6 can also be
utilized to yield the asymmetric
displacement response.
3. Applications
• Applying the asymmetric displacement responses mentioned above,
it is possible to construct some actuator with a function of both
direction operation by only one channel electrical excitation.
Applications
resonance frequency : 110 [kHz]
and the quality factor : 50
resonance frequency : 32.8 [kHz]
and the quality factor : 370
구동원리
Conclusions
• We proposed a new excitation methode of a
piezoelectric vibration without residual
displacement to achieve the asymmetric
displacement responses as a function of time
elapsed, and moreover we presented its
application to construct an actuator.
• We want to investigate piezoelectric actuators
using such a phenomenon and improve their
characteristics further.