• Proceedings of the Korean Society For Composite Materials Conference
• /
• 1999.11a
• /
• pp.124-129
• /
• 1999

In this study, a design method for the flat sound radiator is developed to make new sound radiator system, whose shape is much thinner than that of conventional loudspeaker. Piezofilm (PVDF) is used as actuators of flat sound radiator. To avoid the distortion of sound radiated from flat sound radiator, the frequency response of radiated sound to be flat is taken as the design objective. The electrode pattern and orientation angle of piezofilm actuator is optimized to satisfy the design objective. The formulation is based on the coupled finite element and boundary element method. Genetic algorithm is used in the optimization process, which is useful in the optimization of discrete design variables. Frequency response with optimized piezofilm actuator is made flat enough to satify the design objective. For the enhancement of sound power, double-layered piezofilm actuators are also considered. The sound power with double-layered actuator becomes larger than that with single-layered actuator as expected.

• Journal of Mechanical Science and Technology
• /
• v.17 no.3
• /
• pp.357-369
• /
• 2003

Electromagnetic valve (EMV) actuation system is a new technology for improving fuel efficiency and at the same time reducing omissions in internal combustion engines. It can provide more flexibility in valve event control compared with conventional variable valve actuation devices. The electromagnetic valve actuator must be designed by taking the operating conditions and engine geometry limits of the internal combustion engine into account. To help develop a simple design method, this paper presents a procedure for determine the basic design parameters and dimensions of the actuator from the relations of the valve dynamics, electromagnetic circuit and thermal loading condition based on the lumped method. To verify the accuracy of the lumped method analysis, experimental study is also carried out on a prototype actuator. It is found that there is a relatively good agreement between the experimental data and the results of the proposed design procedure. Through the whole speed range, the actuator maintains proper performances in valve timing and event control.

• Journal of Magnetics
• /
• v.21 no.1
• /
• pp.65-71
• /
• 2016

To increase the retaining force, a novel design for a concentric, bi-directional, electromagnetic valve actuator that contains double-layer permanent magnets is presented in this paper. To analyze the retaining-force change caused by the magnets, an equivalent magnetic circuit (EMC) model is established, while the EMC circuit of a double-layer permanent-magnet valve actuator (DLMVA) is also designed. Based on a 3D finite element method (FEM), the calculation model is built for the optimization of the key DLMVA parameters, and the valve-actuator optimization results are adopted for the improvement of the DLMVA design. A prototype actuator is manufactured, and the corresponding test results show that the actuator satisfies the requirements of a high retaining force under a volume limitation; furthermore, the design of the permanent magnets in the DLMVA allow for the attainment of both a high initial output force and a retaining force of more than 100 N.

• Journal of Magnetics
• /
• v.20 no.1
• /
• pp.69-78
• /
• 2015

This paper focuses on the design of a flux-biased rotary electromagnetic actuator with compact structure for fast steering mirror (FSM). The actuator has high force density and its torque output shows linear dependence on both excitation current and rotation angle. Benefiting from a new electromagnetic topology, no additional axial force is generated and an armature with small moment of inertia is achieved. To improve modeling accuracy, the actuator is modeled with flux leakage taken into account. In order to achieve an FSM with good performance, a design methodology is presented. The methodology aims to achieve a balance between torque output, torque density and required coil magnetomotive force. By using the design methodology, the actuator which will be used to drive our FSM is achieved. The finite element simulation results validate the design results, along with the concept design, magnetic analysis and torque output model.

• Journal of Mechanical Science and Technology
• /
• v.20 no.12
• /
• pp.2087-2093
• /
• 2006

In this paper, auto focus actuator, which is used to move a lens module in the mobile phone having a camera module, is developed. Camera module containing auto focus actuator requires to minimize total size because of characteristics of the application area such as mobile phone, digital camera, and personal digital assistant. There are stepping motor, voice coil motor, and piezoelectric motor as auto focus actuator. In this paper, voice coil motor having new electromagnetic configuration is proposed. And actuator using proposed voice coil motor is developed by optimal design method using magnetic circuit analysis. The sectional area of the developed actuator is reduced to 32.4% compared with actuator using general electromagnetic configuration. From the performance test, the developed actuator has moving stroke of 0.64 mm for 2.1 volt, hysteresis of 40 $\mu$m, full stroke current of 54 mA, and unit step motion of 3 $\mu$m.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.10
• /
• pp.1171-1178
• /
• 2011

This paper shows the robust design results of an actuator, a kind of dynamic system. Variations in the components comprising the actuator cause uncertainties in the system's dynamic performance. Therefore, a probabilistic design method is applied to ensure robust actuator performance to component variation. A Simulink model for the actuator was built using transfer functions for the components. The dynamic responses of the actuator were evaluated using the Simulink model. Performance indexes were approximated as quadratic functions of the design parameters through the application of the response surface methodology (RSM) with the Simulink model. Then, a probabilistic design method was applied to the approximated performance indexes to obtain optimal design parameters that would provide robust actuator performance. The optimal design was compared to the present design in terms of the performance indexes and dynamic response characteristics over time.

• Proceedings of the Korean Society of Laser Processing Conference
• /
• 2006.06a
• /
• pp.129-134
• /
• 2006

In this paper, actuator based on voice coil motor is designed and estimated to check the capability whether that system is in design specification or not. Design specification is moving range as $20{\times}20mm^2$ a along XY-axis in plane and maximizes bandwidth for high speed. The type of voice coil motor is selected with regarding design specification and minimizes the size of actuator. Flux density of designed voice coil motor is simulated. And PI controller is designed to maximize bandwidth of actuator. Finally, characteristic of designed actuator is simulated and that result reveals the validity of presented design.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.30 no.9 s.252
• /
• pp.1102-1109
• /
• 2006

In this paper, 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 effect of CAMD and the performance improvement of actuator are confirmed through Moonie actuator and PZT suspension design.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.05a
• /
• pp.668-673
• /
• 2005

This paper proposes a simple actuator with a spherical rotor for robot's eyeball, which has two degrees of freedom. It features that both permanent magnets and coils are equipped in a stator and the spherical rotor with steps on its surface is driven by reaction of Lorentz force acting on the fixed coils. Such a structure is helpful to design a simple actuator and particularly suitable for a spherical actuator. Based on the FEM analysis, design parameters such as the sizes of core and permanent magnet, the width of step, coil turns and maximum current, are determined so as to maximize the torque and rotating angle. For the experimental verification of the feasibility, a prototype is manufactured and its operating characteristicsareinvestigated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.490-493
• /
• 2004

A 3-DOF actuator which has new principle and very simple structure is proposed. Its principle seems to be similar to conventional electromagnetic actuators, that is, to utilize the relation of control and bias fluxes produced by coils and permanent magnets, respectively, but the coils and permanent magnets of the proposed actuator are fixed in the stator. Such a structure helps to optimally design the actuator for its use. Some experimental and FEM analysis results show the feasibility of the proposed actuator and some characteristics of system that are useful lot structure design and control.