• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1576-1577
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• 2007

As a intelligent valve piezoelectric valve is to applied to various fields of application. Piezoelectric valves have fast response time and good linearity for pressure control but its hysteresis displacement by its stack actuator influences on pressure control in electro-hydraulic braking. Solenoid valves are traditional element to control hydraulic pressure but this paper proposes piezoelectric valve for brake pressure control with hysteresis compensation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.283-286
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• 2004

This work presents a 3-axis active mount featuring the piezoelectric stack actuators. The inertia configuration for the piezoelectric actuators is adopted to achieve appropriate force and moment in each axis. In addition, the rubber mount is integrated to provide stiffness for system loading. In order to analyze the active mount, the governing equation for the force and moment is derived and its validity is demonstrated by comparing generated force and moment of each actuator between analysis and experiment. In addition, the natural frequency of each actuator is identified though both simulation and experiment.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.102-102
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• 2003

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.10a
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• pp.28-33
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• 1996

This paper presents a position control of ultra-precision machine tool post using piezoelectric material. A stack-type piezoelectric actuator is employed in a hinge-type tool holder. An assumed linear transfer function of the practical nonlinear plant is established through the comparison of transfer functions and step responses in the experiments and the simulations. Several types of feedforward/feedback controllers are designed via computer simulations using the assumed linear transfer function, The position tracking control experiments are undertaken to show the control efficiency of each controller.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.4
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• pp.520-528
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• 2015

The piezoelectric-hydraulic actuator is a hybrid device that consists of a hydraulic pump driven by a piezo-stack coupled to a conventional hydraulic cylinder. The actuator is of compact size, but can produce a moderate energy output. Such hybrid actuators are currently being researched and developed in many industrialized countries due to the requirement for high performance and compact flight systems. In a previous study, we designed and manufactured a unidirectional hybrid actuator. However, the blocking force was not as high as expected. Therefore, in this study, we redesigned the pump chamber and hydraulic cylinder and also improved the system by removing the air bubbles. Two different types of piezo-stacks were used. In order to achieve bidirectional capabilities in the actuator, commercial solenoid valves were used to control the direction of the output cylinder. Experimental testing of the actuator in unidirectional and bidirectional modes was performed to examine performance issues related to driving frequency, bias pressure, reed valve thickness, etc. The results showed that the maximum blocking force was measured as 970.2N when the frequency was 185Hz.

• Journal of Power System Engineering
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• v.9 no.4
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• pp.162-167
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• 2005

The purpose of this paper is to improve the hysteresis characteristics of a stack type piezoelectric actuator using system identification and tracking control. Recently, several printing methods that are cost less and faster than previous semiconductor processes have been developed for the production of electric paper and RFID(Radio Frequency IDentification). The system proposed in this study prints by spraying the molten metal. And this system consist of a nozzle, heating furnace, operating actuator and an XYZ 3-axis stage. As an operating system, the piezoelectric(PZT) actuator is a very useful tool for position control of the metal printing system. However, the PZT actuator has a hysteresis nonlinearity due to the ferroelectric characteristics of the PZT element. This hysteresis causes problem position control characteristics in the system and deteriorates the performance of the system. In this study, an investigation was conducted to improve the hysteresis characteristics of the PZT actuator that has an output displacement for the input voltage. In order to reduce the hysteresis nonlinearity of the PZT actuator, this proposed a inverse hysteresis model and a mathematic modeling method that can express the geometric relationship between voltage and displacement. In addition, system identification and PID control methods were examined. Also, it was confirmed that the proposed control strategy gives good tracking performance.

• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.545-550
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• 2013

Piezoelectric PMN-29PT single crystal multilayer actuators [100 $mm^2$ in cross section and 22 mm in length] are designed and fabricated by stacking square plates [$10{\times}10{\times}0.5(t)\;mm^3$] of PMN-29PT single crystals having a $d_{33}$ of about 1,500 pC/N. The characteristics of PMN-29PT multilayer actuators are compared with those of P-025.40P multilayer PZT ceramic actuators [490 $mm^2$ in cross section and 60 mm in length] produced by PI in Germany. Even though the total volume of the PMN-29PT single crystal multilayer actuator is only about 7.5% of that of the P-025.40P ceramic multilayer actuator, PMN-29PT single crystal multilayer actuators are expected to show very similar properties to P-025.40P ceramic actuators in terms of static stroke and blocking force. Therefore, on the basis of their smaller mass and volume compared to the conventional PZT ceramic multilayer actuators, piezoelectric PMN-29PT single crystal multilayer actuators have significant potential regarding the development of various high performance actuators for aerospace subsystems.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.3
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• pp.213-219
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• 2015

Piezoelectric-based hydraulic actuator is a hybrid device consisting of a hydraulic pump driven by piezoelectric stacks that is coupled to a conventional hydraulic cylinder via a set of fast-acting valves. Nowadays, such hybrid actuators are being researched and developed actively in many developed countries by requirement of high performance and compact flight system. In this research, a piezoelectric hybrid actuator has been designed and tested. To achieve bi-directional capabilities in the actuator, solenoid valves were used to control the direction of output fluid. The experimental testing of the actuator in uni-directional and bi-directional modes was performed to examine performance issues related to the solenoid valves. The results showed that the bi-directional performance was slightly lower than uni-directional performance due to air bubble developed in the valve system. A new design to solve the vacuum problem has been proposed to improve the performance of the hybrid actuator.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.1
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• pp.62-71
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• 2009

In this paper, an improved drive method of piezoelectric PZT stack actuator for micro-positioning system is proposed and the performances are evaluated. This type of amplifier is based on switching technology efficiently handling the arbitrary regenerative energy from the piezoelectric actuator. The conventional voltage-feedback control method has the THD of -32dB (${\approx}2.5%$) with 100mHz sinusoidal reference, which means that the positioning performance in linearity degrades due to the hysteretic relationship between actuator voltage and the displacement. This paper proposed an improved charge-controlling method, which utilizes differential information of charge reference instead of integrating the actuator's current. The current waveform has THD under -40dBV (=1%) and the displacement waveform nearly -52dB (${\approx}0.25%$), which means that the positioning performance is very excellent. Finally, another method of the displacement feedback control has better performance than the voltage method, however there exists a limitation in performance of the system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.1
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• pp.25-30
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• 2013

The piezoelectric-based hydraulic actuator is a hybrid device consisting of a hydraulic pump driven by piezoelectric stacks that is coupled to a conventional hydraulic cylinder via a set of fast-acting valves. Nowadays, such hybrid actuators are being researched and developed actively in many developed countries by requirement of high performance and compact flight system. In this research, operation principle and performance testing of the hybrid actuator were introduced. Output velocities have been measured in both loaded case and not loaded case and the blocking force also has been measured in external loaded case. The maximum velocity of the actuator is 53.3 mm/s, blocking force is 240.7 N and corresponding power output is 3.2 W.