• Smart Structures and Systems
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• 제10권6호
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• pp.501-515
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• 2012

We design and test a shape memory alloy (SMA)-based actuation system that can be used to propel a fish robot. The actuator in the system is composed of a 0.1 mm diameter SMA wire, a 0.5 mm-thick glass/epoxy composite strip, and a fixture frame. The SMA wire is installed in a pre-bent composite strip that provides initial tension to the SMA wire. The actuator can produce a blocking force of about 200 gram force (gf) and displacement of 3.5 mm at the center of the glass/epoxy strip for an 8 V application. The bending motion of the actuator is converted into the tail-beat motion of a fish robot through a linkage system. The fish robot is evaluated by measuring the tail-beat angle, swimming speed, and thrust produced by the tail-beat motion. The tail-beat angle is about $20^{\circ}$, the maximum swimming speed is about 1.6 cm/s, and the measured average thrust is about 0.4 gf when the fish robot is operated at 0.9 Hz.

• 산업기술연구
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• 제28권A호
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• pp.155-161
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• 2008

Muscle force prediction in forward dynamic analysis of human motion depends many muscle parameters associated with muscle actuation. This research studies the effects of various parameters of Hill type muscle model using the simple hand raising motion. Motion analysis is carried out using motion capture system, and each muscle force is recorded for comparison with muscle model generated muscle force. Using Hill type muscle model, muscle force for generating the same hand rasing motion was setup adjusting 5 activation parameters. The test showed the importance of activation parameters on the accurate generation of muscle force.

• 항공우주기술
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• 제12권1호
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• pp.54-63
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• 2013

항공기의 자세제어를 담당하는 각각의 비행 조종면에 중복안정성 등의 이유로 여러 개의 작동기를 연결하여 사용하고 있다. 다중 작동기들이 동시에 정확하게 같은 위치로 이동하지 않으면 비행조종면에 변형이 발생한다. 그 결과 변형된 조종면이 원래 상태로 복원하려는 힘에 의해 작동기들 간에 force fighting이 발생한다. 게다가 force fighting은 각 장치들의 초기 허용 오차 등에 의해서도 발생한다. 다중 작동기간의 force fighting 현상은 제어정밀도에 영향을 미치고 피로파괴의 원인이 되어 작동기와 비행조종면의 수명을 단축할 수도 있다. 본 논문에서는 두 개의 서보작동기를 사용하는 시스템의 force fighting을 감소하기 위하여 힘되먹임제어를 사용하는 제어기를 설계하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.929-932
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• 2005

We report a pull-up type RF MEMS switch using double electrode without elastic deformation of the cantilever involved in the actuation. At a voltage of 4.5 V, reliable actuations are achieved such that the movable lower contact pad is pulled up by the electrostatic force to make contact with the upper pad. At a frequency of 50 GHz, an insertion loss of 0.7 dB and an isolation of 50.7 dB are obtained from the switch. The measured transient times for switch-on and switch-off are 120 and 80 us, respectively.

• 제어로봇시스템학회논문지
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• 제16권9호
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• pp.846-851
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• 2010

In this paper, we newly propose a novel control strategy of a three joints-robot finger for the purpose of artificial hands. The robot finger is specifically modeled by using a 3D CAD program (CATIA), considering human fingers, and then the proposed control method is verified through the dynamic simulation tool (Simulink and Recurdyn R2). Each slider is individually controlled to be located at the optimal positions where the maximal joint torque can be generated. To prove the effectiveness of the proposed control method, we devise two cases for the reference position of sliders. By comparing the control performance of two cases, the validity of the proposed control method will be verified.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.210-215
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• 2008

This paper presents an experimental study on a bending actuator with a shape memory alloy wire. In this study, we introduced design process and experimental result of the bending actuator. The bending actuator consists of a SMA wire, springs, and a glass/epoxy strip. In the bending actuator, springs were used to restore the SMA wire to its initial shape right after actuation. To obtain properties of the SMA wire, DSC test was performed and the behavior of the SMA wire under different loadings was observed. Finally, the proposed bending actuator shows reasonable actuation behavior with relatively lower power consumption, fast response and effective efficiency.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.2260-2262
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• 2000

In this paper, micromirror which can rotate 45 degree is designed, analyzed and fabricated. The micromirror is parallel to the substrate initially. When external magnetic field is applied, a micromirror can rotate to align its easy axis to the field. The size of micromirror array is $10{\times}10$. The mirror plate and spring is made of aluminium, and nickel is used as soft magnetic material. To obtain 45 degree angular deflection, dimension ratio between stopper length and thickness of sacrificial layer is properly selected. By using electrostatic force, individual actuation is possible.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권1호
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• pp.55-59
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• 2003

With the progress of optical communication technology recently, the development of micro actuator using MEMS technology has been made for optical switching. The actuation types are various; electrostatic, electromagnetic, and electrostatic +electromagnetic etc. Among them, the electrostatic type is the most popular because of the relative ease of fabrication, integration and shielding as well as low power consumption. However, it needs a high voltage to generate a larger driving force. To overcome this problem, we proposed a new type of electrostatic actuator with an extra vertical electrode in addition to the horizontal one. The vertical electrode also lays a role of making the stable angular rotation as a stopper. From the theoretical analysis and experiment, we find the actuation voltage can be reduced up to 50 % of that of the conventional one.

• 한국정밀공학회지
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• 제13권9호
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• pp.54-61
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• 1996

Because of its high energy density, the use of shape memory alloys(SMA) in designing microactuatiors is gaining much attention in recent years. Shape memory alloys can undergo a shape change at a low temperature with a small applied deformation force, and retain this deformation until they are heated, at which point they return to the original shape. This is called the shape memory effect(SME), and a plethora of alloys show this effect. Among them, TiNi-based alloys have relatively high electrical resistivity, which to develope helical-shape memory springs. These springs are used to develop fast protatonist/antagonist configuration actuators. The developed actuator has an actuation speed of 1 mm per 15 .approx. 20 ms and a minimum operating period of 2 sec.

• 한국정밀공학회지
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• 제19권3호
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• pp.137-143
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• 2002

This paper presents the In-process compensation to control cutter runout and improve the machined surface quality. Cutter runout compensation system consists of the micro-positioning servo system with piezoelectric actuator which is embeded in the sliding table to manipulate radial depth of cut in real-time. Cutting force feedback control was proposed in the angle domain based upon repetitive learning control strategy to eliminate chip load variation in end milling process. Micro-positioning control due to adaptive actuation force response improves the machined surface quality by compensation runout effect induced cutting force variation. This result will provide lots of information to build-up the preciswion machining technology.