Abstract: This paper presents the design, fabrication, and performance test of a gap adjustable
piezoelectrically-actuated DoD(drop-on-demand) molten metal injector for application to the 3D
microstructure manufacturing or printed electronics. In the design process, we propose the gap
adjustable mechanism of the piezoelectrically-actuated inkjet system to control the volume and
velocity of the ejected molten metal droplets. In the experimental process, we fabricate the DoD
metal injector and measure the volumes and velocities of the ejected droplets for molten metal as
well as pure water to compare the ejecting performance for the different viscosity of ink and the
operating temperature of the system.
Abstract: A smart material actuator is required for a smart structure having multifunctional performance.
Among the smart material actuators, piezoelectric actuator is known for its excellent large force generation
in broad bandwidth in a compact size. However it needs relatively large actuation voltage requiring a bulky
hardware system. This study is mainly concerned to develop a self-powered miniaturized piezoelectric
actuator driver (MIPAD) controlled by a radio controller for small sized piezoelectric smart structures. It can
receive command from other microprocessors or a remote radio controller. We designed a real hardware and
it demonstrated good performances even though the driving system was very small. The MIPAD is expected
to minimize the weight and size of the piezoelectric actuator system and it can be easily embedded into
mobile smart structures.
Abstract: This paper presents a computer-based tracking control approach for a piezoelectric
actuator based on incorporating a feedforward loop with a PID feedback controller. The purpose of
this paper is to improve the hysteresis characteristics of a stack type piezoelectric actuator using the
hysteresis nonlinearity compensator. The system proposed in this study prints by spraying the
molten metal, and consists of a nozzle, heating furnace, operating actuator, and an XYZ 3-axis stage.
As an operating system, the piezoelectric(PZT) method has very valuable uses. The PZT actuator,
however, has a hysteresis nonlinearity due to the ferroelectric characteristics of the PZT element.
This causes problems in the system position control characteristics and deteriorates the performance
of the system. This study proposed a inverse hysteresis model, a mathematic modeling method that
can express the geometric relationship between voltage and displacement, in order to reduce the
hysteresis of the PZT actuator. In addition, system identification and PID control methods were
examined. Also, it was confirmed that the proposed control strategy gives good tracking
Abstract: In this work, behavior of a unimorph piezoceramic actuator, LIPCA (Lightweight Piezo-
Composite Actuator) has been numerically and experimentally investigated. By measuring the
lateral displacement created by the compressive load, the buckling load of the LIPCA was
determined. Under simply supported configuration, the measured buckling load agreed well with
the geometrically nonlinear buckling load from the finite element analysis. The measured data
shows that the lateral displacement of the LIPCA is significantly increased when the electric field is
prescribed to the LIPCA in addition to the compressive load. The measured data was compared
with the computed results from the geometrically nonlinear finite element analysis. The numerical
simulation agreed well with the measurement for low compressive load and low electric field.
Abstract: In the design of piezoelectric actuator the concept of compliant mechanism combined
with piezoelectric materials has been used to magnify either geometric or mechanical advantage.
The polarization of piezoelectric materials is considered to improve actuation since the piezoelectric
polarization has influences on the performance of the actuator. The topology design of compliant
mechanism can be formulated as an optimization problem of material distribution in a fixed design
domain and continuous approximation of material distribution(CAMD) method has demonstrated
its effectiveness to prevent the numerical instabilities in topology optimization. The optimization
problem is formulated to maximize the mean transduction ratio subject to the total volume
constraints and solved using a sequential linear programming algorithm. The performance
improvement of Moonie actuator design confirms an effect of polarization direction and CAMD.
Abstract: Research on piezoelectric unimorph actuators has been intensively increased during the
past decade due to the wide applications of this actuator type in aerospace, vibration control,
biomimetic robots, artificial muscles… Most analyses focused on the design performance with
load-free actuating condition. Loading performance has not been considered adequately yet though
in real application the actuators always work under certain carrying load. This paper introduces the
measuring system, the experimental setup and presents the observed loading performance of the
actuators with center load. Two typical kinds of piezoelectric unimorph actuator, LIPCA-C3 and
THUNDER, are investigated. The numerical analyses are also conducted to illustrate the loading
behavior of these devices. Some remarks and suggestions for future research activities are drawn.
Abstract: To identify a delamination crack in a CFRP laminate wirelessly, we proposed an electric
resistance change method with oscillating circuit in the previous study. Although the method detects
the delamination creation, it cannot monitor condition of applied strain before delamination creation
because the electric resistance change due to strain changing is quite small. In the present study, a
bridge circuit, two amplifiers and voltage-controlled oscillator are added to sensing circuit so that it
can monitor very little change of the electric resistance change. Using proposed strain sensing
system, the electric resistance change and oscillating frequency change due to strain changing are
experimentally measured. As a result, the method is found to successfully monitor the applied
Abstract: In the present paper, the dynamic characteristics of smart hull structure are investigated
for the feasibility of Macro Fiber Composite (MFC) actuator in active vibration control of smart
hull structure. MFC is an advanced anisotropic piezoceramic actuator. Finite element technique was
used to ensure application to practical geometry and boundary conditions of smart hull structure.
Using finite element method, modal analysis and strain distribution were first conducted to
investigate dynamic characteristics of smart hull structure. Based on numerical modal analysis, the
locations of MFC actuators are determined to achieve maximum control authority. Then, the MFC
actuators are attached to the hull structure and natural frequencies and damping coefficients are
identified through experimental modal test.
Abstract: CFRP laminate can be used itself as a sensor for detecting own damage. The authors have
introduced electric resistance change method and asymmetrical dual charge electric potential
change method to detect a delamination in the CFRP laminate. Although the methods showed good
performance of estimation analytically and experimentally, those are sensitive to electromagnetic
noise. Experimental error caused by such noise in the actual use may affect the accuracy of
estimation. In this paper, influence of the noise on accuracy of estimation was investigated
quantitatively using finite element analysis. It was clarified that the methods have different
characteristics for experimental noise.
Abstract: Drivers are becoming more fatigued and uncomfortable as traffic densities increase, and
so, can show slower reaction time. They then face the danger of traffic accidents due to their
inability to cope with frequent shifting. To reduce this risk, some drivers prefer automatic
transmissions to manual transmissions. However, automatic transmission requires both higher fuel
consumptions and costs. For this reason, attention to automated manual transmission that can
provide high efficiency, low cost and easy manufacturability has been increasing. In addition, the
function and performance of the electronic control unit of automobiles has improved continually
and rapidly with the growing electronics technology. The ECU is a representative embedded system
in automobiles, which has to satisfy high performance and reliability under the constraints of size
and cost. In this paper, the embedded system platform for automobiles is developed on the basis of
MPC565, and a test rig is developed to perform the basic function test for automatic clutch
actuation. The developed embedded system and clutch control algorithm are validated by the
experimental results performed on the test rig.