• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.3
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• pp.242-247
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• 2016

This work investigates the performances of active hood lift system(AHLS) activated by two different operating methods through the experimental test. In the AHLS, the deployment time of the system and decrement of pedestrian injury are the most important factors for the pedestrian safety during the pedestrian-vehicle impact. After introducing the working principle of AHLS using spring actuator and gunpowder actuator, the deployment time of AHLS and decrement of pedestrian injury are evaluated by the experimental test. It has been identified that the gunpowder actuator can provide a faster deploying time of AHLS.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.10
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• pp.83-88
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• 2000

multi-beam optical drive is a method to improve the data transfer rate for the optical disc systems by parallel recording and reading on neighboring multi-tracks. In this paper, the beam rotating actuator, which is necessary for the multi-bean optical disc drive to from beam spots on multi-tracks simultaneously, has been developed. The Voice Coil Motor is used as a drive mechanism for high resolution and small size of the actuator. And rotating guide based on link structure is designed for frictionless and axisless rotation of rotating part including dove prism and for rotating in axis of geometric center of dove prism. The characteristics of the actuator are experimented by laser vibrometer, Polytec OFV1102 and a dynamic analyzer, HP35670A. It shows that the actuator has good linearity, rotating range $\pm0.34^\circ$, minimum rotating angle $0.0066^\circ$and natural frequency 113.9Hz. Therefore the actuator can be applied in a multi-beam optical disc system.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.11
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• pp.1259-1264
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• 2011

This paper suggests a new film-type haptic actuator based on cellulose acetate electro-active paper. Conventional tiny haptic actuators in mobile devices can create vibrotactile sensation at only near resonant frequency. The strategy of operating near the resonant frequency, however, brought a new issue for creating vibrotactile sensation which can be strong enough to feel in arbitrary frequency. Another problem is that the size of the conventional actuator is not small enough to be embedded into slim mobile devices. In order to achieve these issues, we propose a thin and tiny actuator based on a cellulose acetate material charged with an electric potential. The motion of the actuator can be a concave or a convex by controlling a polarity of both charged membranes and the actuator performance can be modulated by increasing level of biased electric potential.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.12
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• pp.1529-1534
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• 2013

A voice coil actuator with a rotating moving magnet has been developed for a miniaturized mobile robot. The actuator has simple structure comprising a magnet, a coil, and a yoke. Actuator performance is predicted using a linearized theoretical model, and dynamic performance based on the air-gap between the magnet and the coil is predicted using motor constant and restoring constant obtained through finite element simulations. The theoretical model was verified using a prototype with 60 Hz resonance and 80 Hz bandwidth. We found that an input of 1.5 V can make the actuator rotate by $20^{\circ}$ statically. The driving configuration of the proposed actuator can be simplified because of its implementation of open-loop control.

• Journal of Mechanical Science and Technology
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• v.16 no.5
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• pp.639-646
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• 2002

In this paper, thrust equations for a rubber belt CVT are derived by considering the geometry and mechanism of the mechanical actuators. In order to solve the thrust equations, an algorithm to calculate the speed ratio is suggested for the given driver speed and load torque based on the actuator characteristic equations and existing formula for the belt thrust forces. Experiments are performed to investigate the driver speed-load torque-speed ratio characteristics at a steady state. The speed and torque efficiencies are measured and used to modify the actuator equations. It is found that the modified equations well predict the steady state characteristics. In addition, the shift dynamic model for a rubber belt CVT is derived experimentally. Simulation results of the CVT shift dynamics are in good accordance with the experiments and it is noted that different coefficients are required to describe the CVT shift dynamics for the upshift and the downshift.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.2
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• pp.81-85
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• 2017

Fiber-reinforced polymer composites, which are made by combining a continuous fiber that acts as reinforcement and a homogeneous polymeric material that acts as a host, are engineering materials with high strength and stiffness and a lightweight structure. In this study, a shape memory alloy(SMA) reinforced composite actuator is presented. This actuator is used to generate large deformations in single lightweight structures and can be used in applications requiring a high degree of adaptability to various external conditions. The proposed actuator consists of numerous individual laminas of the glass-fiber fabric that are embedded in a polymeric matrix. To characterize its deformation behavior, the composition of the actuator was changed by changing the matrix material and the number of the glass-fiber fabric layers. In addition, current of various magnitudes were applied to each actuator to study the effect of the heating of SMA wires on applying current.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.2
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• pp.108-115
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• 2015

Electro-mechanical actuator installed on aircraft consists of a decelerator which magnifies the torque in order to rotate an axis connected with aircraft control surface, a control section which controls the motor assembly through receiving orders from cockpit and a motor assembly which rotates the decelerator. Electro-mechanical actuator controls aircraft altitude, position, landing, takeoff, etc. It is an important part of a aircraft. Aircraft maneuvering causes vibrations to electro-mechanical actuator. Vibrations may result in structural fatigue. For that reason, it is necessary to analyze the system structural safety. In order to analyze the system structural safety. It is needed reasonable finite element model and structural response stress closed to real value. In this paper, analytic model is derived by using the simplified finite element model, and damping ratio which is closely related to response stress is derived by using modal test. So, we developed analytic model in less than 10 % error rate, compared with modal test. Vibration response stress close to real value was estimated from analytic model modified with modal experimental damping ratio. Estimation method for damping ratio with empirical formula was suggested partly. Finally, It was proved that electro-mechanical actuator had reasonable structure margin of safety at environmental random $3{\sigma}$ stress during life cycle.

• The Journal of Korea Robotics Society
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• v.8 no.3
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• pp.150-155
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• 2013

Vibrotactile actuators for small consumer electronic products, such as mobile devices, have been widely used for conveying haptic sensation to users. One of the most important things in vibrotactile actuators is to be developed in the form of thin actuator which can be easily embedded into mobile devices and to provide vibrotactile signals with wide frequency band to users. Thus, this paper proposes a thin film type haptic actuator with an aim to convey vibrotactile information with high frequency bandwidth to users in mobile devices. To this end, a vibrotactile actuator which creates haptic sensation is designed and constructed based on cellulose acetate material. A cellulose acetate material charged with an electric potential can generate vibration under the AC voltage input. It is found that the motion of the actuator can have concave or convex shape by controlling a polarity of both charged membranes and the actuator performance can be modulated by increasing level of biased electric potential. The experiment clearly shows that the proposed actuator creates enough output force to stimulate human skin with a large frequency bandwidth and to simulate various vibrotactile sensations to users.

• International Journal of Control, Automation, and Systems
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• v.1 no.3
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• pp.315-320
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• 2003

This paper presents a control augmentation system (CAS) based on the dynamic model inversion (DMI) architecture for a highly maneuverable aircraft. In the application of DMI not treating actuator dynamics, significant instabilities arise due to limitations on the aircraft inputs, such as actuator time delay based on dynamics and actuator displacement limit. Actuator input saturation usually occurs during high angles of attack maneuvering in low dynamic pressure conditions. The pseudo-control hedging (PCH) algorithm is applied to prevent or delay the instability of the CAS due to a slow actuator or occurrence of actuator saturation. The performance of the proposed CAS with PCH architecture is demonstrated through a nonlinear flight simulation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.12
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• pp.1066-1072
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• 2013

In this work, active control algorithm is adopted to reduce delamination effects of the damaged composite structure and control performance with MFC actuator is numerically evaluated. Finite element model for the damaged composite structure with piezoelectric actuator is established based on improved layerwise theory. In order to achieve high control performance, MFC actuator, which has increased actuating force, is considered as a piezoelectric actuator. Mode shapes and corresponding natural frequencies for the damaged smart composite structure are studied. After design and implementation of active controller, dynamic characteristics of the damaged smart composite structure are investigated.