• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.24.2-27
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• 1996

This paper is a study on the fuzzy force control of a miniature gripper driven by piezoelectric bimorph actuator. The system is composed of two flexible cantilevers, a stepping motor, a laser displacement transducer and two semiconductor force sensors attached to the beams. Obtained results show that the present artificial finger system works well as a miniature gripper, which produces approximately 0.06N force in the maximum. Further, the fuzzy position/force control algorithm is applied to the soft-handing gripper for stable grasping of a object. It revealed that the fuzzy rule-based controller be efficient controller for the stable drive of the flexible miniature gripper. It also showed that two semiconductor strain gauges located in the flexible beam play an important roles for force control, position control and vibration suppression control.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.924-927
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• 2004

Measurements of fluctuating wall pressures were made with a linear array of 16 piezo-electric transducers beneath a fully-developed turbulent boundary layer. The piezoelectric bimorph actuator applied in this experiment has bonding structures of each polarity to make out-of-plane displacements rather than in-plane ones by using piezoelectric effect To specify the boundary layer characteristics at the location where the actuation was applied, the wall friction coefficients and $Re_\theta$ were measured by using the CPM method. The actuating frequency for the bimorph film was determined according to the priori bursting frequency from boundary layer parameters. The reduction of convecting energies in wave-number space was clearly observed at the specified actuating frequencies.

• Smart Structures and Systems
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• 제26권3호
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• pp.391-401
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• 2020

The present article reports the feasibility of the electrical energy generation from ambient low-frequency vibration using a piezoelectric material mounted on a bimorph cantilever beam actuator. A corresponding higher-order analytical model is developed using MATLAB in conjunction with finite element method under low-frequency with both damped and undamped conditions. An alternate model is also developed to check the material and dimensional viability of both piezoelectric materials (mainly focussed to PVDF and PZT) and the base material. Also, Genetic Algorithm is implemented to find the optimum dimensions which can produce the higher values of voltage at low-frequency frequencies (≤ 100 Hz). The delamination constraints are employed to avoid inter-laminar stresses and to increase the fracture toughness. The delamination has been done using a Teflon sheet sandwiched in between base plates and the piezo material is stuck to the base plate using adhesives. The analytical model is tested for both homogenous and isotropic material characteristics of the base material and extended to investigate the effect of the different geometrical parameters (base plate dimensions, piezo layer dimensions and placement, delamination thickness and placement, excitation frequency) on the model responses of the bimorph cantilever beam. It has been observed that when the base material characteristics are homogenous, the efficiency of the model remains higher when compared to the condition when it is of isotropic material. The necessary convergence behaviour of the current numerical model has been established and checked for the accuracy by comparing with available published results. Finally, using the results obtained from the model, a prototype is fabricated for the experimental validation via a suitable circuit considering Glass fibre and Aluminium as the bimorph material.

• Journal of Mechanical Science and Technology
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• 제20권11호
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• pp.1993-2001
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• 2006

The piezoelectric bimorph film, which, as an actuator, can generate more effective displacement than the usual PVDF film, is used to control the turbulent boundary-layer flow. The change of wall pressures inside the turbulent boundary layer is observed by using the multi-channel microphone array flush-mounted on the surface when actuation at the non-dimensional frequency $f_b^+$:=0.008 and 0.028 is applied to the turbulent boundary layer. The wall pressure characteristics by the actuation to produce local displacement are more dominantly influenced by the size of the actuator module than the actuation frequency. The movement of large-scale turbulent structures to the upper layer is found to be the main mechanism of the reduction in the wall- pressure energy spectrum when the 700$700{\nu}/u_{\tau}$-long bimorph film is periodically actuated at the non- dimensional frequency $f_b^+$:=0.008 and 0.028. The biomorph actuator is triggered with the time delay for the active forcing at a single frequency when a 1/8' pressure-type, pin-holed microphone sensor detects the large-amplitude pressure event by the turbulent spot. The wall-pressure energy in the late-transitional boundary layer is partially reduced near the convection wavenumber by the open-loop control based on the large amplitude event.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.330-330
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• 2008

$Fe_2O_3$ added Pb$(Ni_{1/3}Nb_{2/3})O_3-PbTiO_3-PbZrO_3 $ (PNN-PT-PZ) ceramics were produced in order to use them as a bimoph acturator for energy harvesting. Especially, the 0.25 wt% $Fe_2O_3$ added 0.4PNN-0.357PT-0.243PZ, having the composition of morphotropic phase boundary, showed good piezoelectric properties of $d_{33}$ of 810 pC/N, $k_p$ of 77% and $Q_m$ of 55 along with a high Curie temperature of $210^{\circ}C$. A bimorph actuator, composed of the two piezoelectric layers bonded together with a phosphorous bronze layer as a central metallic electrode, was successfully fabricated. The bimorph actuator, vibrated with a 1.3 mm amplitude at 68 Hz, produced high electric power of approximately 60 mW.

• Journal of KSNVE
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• 제7권3호
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• pp.377-386
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• 1997

A cantilever type piezoceramic vibration sensor was developed that could make up for the short-comings of current vibration sensors, such as high price, low sensitivity, and complex structure. For the design, in conjunction with piezoelectric constitutive equations, we derived full analytic response equations of the piezoelectric bimorph sensor to external forces. The external forces were supposed to take the form of either step or sinusoidal force. Based on the results, actual piezoelectric vibration sensors were fabricated and tested for verification of the theoretical results. Further, comparison of the performance of the developed sensor was made with that of a commercially available representative vibration sensor so that quantitative evaluation of its sensitivity could be made. The sensor developed in this work showed excellent sensitivity and thermal stability in addition to the merits of simple structure and low fabrication cost in comparison with conventional mass-loaded piezoelectric sensors.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.488-491
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• 2006

In this paper, a slim type actuator is proposed rising a bimorph PZT and a circular rotor link. The bimorph contacts the circular rotor, and its displacement generates the rotational motion of the rotor. The rotor causes the linear motion of AF and zoom lens through gear and a motion guide. The proposed model enables the actuations of many lens groups for zoom module by extending the single lens model. The important design parameter is the contact force determined by the frictional coefficient and preload between the rotor and PZT bimorph. A prototype of the single actuator model is manufactured and experiments results using LDV and tachometer are compared to the theoretical and numerical predictions. Experiments show the linear bimorph actuator model meets the performance criteria of the lens actuation, and it can be applicable to various slim type actuators for AF and zoom motions in mobile cameras.

• Proceedings of the KIEE Conference
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.806-809
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• 1988

The frequency response characteristics of a bimorph type PZT piezoelectric transducer was investigated. In this study, function generator which generates short burst signal, plane reflection plate and oscilloscope were used to measure the characteristics of piezoceramic ultrasonic transducer. The resonant frequency of a bimorph type piezoceramic transducer which is acquired by using Tone-Burst Method had good agreement with the measured results from spectrum analyzer.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제28권2호
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• pp.133-142
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• 2004

In this article, the constitutive relations of three types of piezoelectric benders, which are a unimorph bender, a bimorph bender and a triple-layer bender, are derived based on the beam theory under the quasi-static equilibrium condition. The relation coefficients are described as the geometry and material properties of the benders. More general constitutive relations involving fixed-free, fixed-roll, and fixed-simply supported boundary conditions under the inconsistent length condition between the piezoelectric layer and the nonpiezoelectric one are discussed. The complicated constitutive relations can be easily calculated and checked by using the symbolic function in ‘Mathematica’. The relation coefficients for the benders are plotted in three dimensional graph using the developed program.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.379-382
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• 2004

In this paper, it is investigated in advance about the PZT-based composition for piezoelectric vibration device. The specimens of piezoelectric ceramics are made of Columbite method. The piezoelectric vibration device by this composition is designed by ATILA(Magsoft) program used FEM(Finite Element Method). The vibration device used for mobile phone must be driven in the frequency of $130{\sim}200Hz$, so the resonant frequency of piezoelectricity must adjust driven frequency bandwidth. The result of analysis by ATILA is appeared dependant property of length, width, thickness and dummy weight about resonant frequency of the piezoelectric vibration device. The size of manufactured actuator is $28{\times}12{\times}0.3mm^3(length {\times}width{\times}thickness)$ and this is bimorph type. The test of manufactured piezoelectric vibration device measure displacement, acceleration and power dissipation. The piezoelectric vibration device has the advantage more than electro-magnetic motor, however the size of manufactured device is larger than electro-magnetic motor.