LIPCA 작동기로 구동되는 날갯짓 기구의 설계 및 성능평가

이승식(Seungsik Lee),모 시아푸딘(Moh. Syaifuddin),박훈철(Hoon Cheol Park),윤광준(Kwang Joon Yoon),구남서(Nam Seo Goo) 한국항공우주학회 2005 韓國航空宇宙學會誌 Vol.33 No.12

본 논문에서 LIPCA(Lightweight Piezoceramic Composite Actuator)를 이용한 날갯짓(flapping) 기구의 개발에 관한 최근의 연구진척 사항을 제시하였다. 날갯짓 기구는 여러개의 연결막대를 이용하여 LIPCA의 제한된 작동변위를 커다란 날갯짓 각(flapping angle)이 발생하도록 증폭시켰으며, 패더링 메커니즘(feathering mechanism)을 적용하여 날갯짓과 동시에 날개에 비틀림이 발생하도록 설계되었다. 이 날갯짓 기구의 고유 날갯짓 주파수는 약 9㎐로, 이때 최대의 날갯짓 각이 발생하였다. 제작된 날갯짓 기구의 작동성능을 평가하기 위하여 날갯짓 주파수를 4㎐에서 15㎐까지 변화시키면서 발생되는 양력과 추력을 측정하였으며, 최대 양력과 최대 추력은 고유 날갯짓 주파수 부근에서 계측되었다. In this paper, we present our recent progress in the LIPCA (Lightweight Piezo-Composite Actuator) application for actuation of a flapping wing device. The flapping device uses linkage system that can amplify the actuation displacement of LIPCA. The feathering mechanism is also designed and implemented such that the wing can rotate during flapping. The natural flapping-frequency of the device was about 9 ㎐, where the maximum flapping angle was achieved. The flapping test under 4 ㎐ to 15 ㎐ flapping frequency was performed to investigate the flapping performance by measuring the produced lift and thrust. Maximum Lift and thrust were produced when the flapping device was actuated at about the natural flapping-frequency.

Reanalysis of Flapping on Level Approach

Kwan-Young Oh 한국영어학학회 2012 영어학연구 Vol.18 No.3

The purpose of this study is to consider flapping of English stops within a word in different aspects of approaches. First, for specification of accurate environments of flapping, we review a few types of rules and contexts of flapping from stress, syllable structure, and foot, and then suggest a modified version of the flapping rule. In addition, for the purpose of surveying the existing analyses of flapping, this paper reconsiders flapping based on resyllabification, ambisyllabicity, and prosodic rule applications. Finally, to show the explanatory superiority of the level-based approach, this paper compares rule-based and syllabification-based approaches with a few examples of the occurrence of flapping.

Effect of flexibility on flapping wing characteristics in hover and forward flight

Lee, Namhun,Lee, Seungsoo,Cho, Haeseong,Shin, SangJoon Elsevier 2018 Computers & fluids Vol.173 No.-

<P><B>Abstract</B></P> <P>Wing flexibility affects the flight performance of flapping-wing micro air vehicles. In this paper, we present a computational approach for the aeroelastic analysis of realistic insect-like flexible flapping wings with hovering and forward-flight modes. A three-dimensional preconditioned Navier–Stokes solver is used with a deforming mesh technique for the aerodynamic analysis of a flapping wing. For the structural analysis, co-rotational (CR) finite elements and CR shell elements are used. As seen from the numerical analysis, wing flexibility leads to thrust increments with the increasing flapping frequency. The advance ratio, however, is the cause of the thrust decrease for flexible flapping wings with high flapping-frequency motions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A aeroelastic analysis of a realistic insect-like flexible flapping wing with hovering and forward-flight modes is presented. </LI> <LI> A three-dimensional preconditioned Navier-Stokes solver and a structural solver with co-rotational (CR) finite elements and CR shell elements are used for the aeroelastic analysis. </LI> <LI> The thrust and lift forces of the flexible wing increase as the flapping frequency increases, but they decrease as the advance ratio increases. </LI> </UL> </P>

Design and Research on Mechanism of Bionic Flapping-wing Air Vehicle

보안공학연구지원센터(IJHIT) 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.4

The fly mechanism and motion characteristics of the birds were analyzed. By the bionics principle, a new bionic flapping wing mechanism was proposed in order to imitate the motion of bird wing. The virtual prototype of this mechanism was established through ADAMS, then the kinematic simulation analysis was applied to the prototype in order to validate the feasibility of this mechanism. And a computational fluid dynamics software, named Fluent was employed to analyze the aerodynamic force of bionic wing. These results shorten the period of manufacturing of flapping wing mechanism, and can provide theoretical basis for the research and manufacture of bionic flapping wing robot.

Characteristics of an Insect-mimicking Flapping System Actuated by a Unimorph Piezoceramic Actuator

Nguyen, Viet-Quoc,Syaifuddin, M.,Park, H.C.,Byun, D.Y.,Goo, N.S.,Yoon, K.J. SAGE Publications 2008 Journal of intelligent material systems and struct Vol.19 No.10

<P>This study introduces an insect-mimicking flapping-wing system, where the rotation, corrugation, and clapping of insect wings have been mimicked. Unlike most motor-driven flapping systems, the flapping in this system is actuated by a unimorph piezoceramic actuator. The artificial wings are first made of a thin polyethylene sheet and then corrugated. As the wings are assembled through a pitching hinge, they can passively rotate about the hinge during the flapping motion due to the resultant aerodynamic force. The effects of the rotation, corrugation, and clapping of the wings are experimentally explored with respect to the vertical force produced by the flapping system. A smoke-wire flow visualization is also conducted to confirm whether the flapping-wing system can generate leading edge and trailing edge vortices, which are essential for generating lift and thrust in insect flight.</P>

향상된 수동 날개 회전을 갖는 곤충 모방 날갯짓 장치

H.V. Phan,Q.V. Nguyen,H.C. Park(박훈철),N.S. Goo(구남서),D.Y. Byun(변도영) 한국항공우주학회 2011 한국항공우주학회 학술발표회 논문집 Vol.2011 No.11

본 연구에서는 날갯짓 장치의 개선을 위하여, 날개를 유연 힌지 없이 직접 날갯짓 기구에 연결하고, 날개 뿌리 부분의 날개 뒷전을 날갯짓 장치 몸체에 연결함으로써, 날갯짓 동안 날개가 반능동적으로 날개 회전이 발생하도록 하였다. 이로써 날개 뿌리에서는 날개 회전이 적고 끝단 끝단에서는 날개 회전이 크도록 하여, 실제 장수풍뎅이의 날갯짓 궤적과 유사하게 하였다. 사전 연구에서 개발한 swing test 장치를 이용하여 수정된 날갯짓 장치의 추력을 측정한 결과, 수정된 날갯짓 장치는 유연 힌지를 갖는 이전의 날갯짓 장치보다 10% 이상 더 큰 추력이 발생함을 확인하였다. 이로써 반자동 날개 회전이 추력을 향상하는데 효과적임을 입증하였다. In this work, we modified the previous flapping-wing system such that it can produce higher force. The wings were directly connected to the output links of the flapping mechanism without flexible hinges. Instead, the trailing edges of the wings near wing root were connected to the body, so that the wings can create semi-active wing rotation. Consequently, the wing rotation angle becomes variable from the wing root to wing tip during flapping. Threedimensional wing kinematics was measured by using two high-speed cameras and compared it with that of the previous flapping-wing with similar wing span, wing area, and flapping frequency. We also measured the thrust by using the swing test method. The measured thrust of the modified flapping-wing system is more than 10% higher than that of the previous one. Thus, the semi-active wing rotation mechanism is proven to improve thrust production.

곤충형 날갯짓 비행체의 회전력 발생장치 설계 및 개선

공두현,이다운,전재혁,신상준 제어·로봇·시스템학회 2019 제어·로봇·시스템학회 논문지 Vol.25 No.11

This paper presents designs and experimental results of moment-generating mechanisms for an insect-like flapping-wing vehicle. The first mechanism was combined with a six-link flapping mechanism, which moves a pair of joints in the flapping mechanism to tilt a trajectory of the flapping wings. The second mechanism was a trailing edge control module designed and manufactured extraneously to the flapping mechanism that tilts the trailing edge shaft to adjust the angle of attack of each wing. This second mechanism produces larger control moments than the first mechanism and can be designed and fabricated independently of the flapping mechanism due to modularization.

Design of control moment generator for insect-mimicking flapping-wing micro air vehicle

Vu Hoang Phan(판 흐앙 부),Hoon Cheol Park(박훈철) 한국항공우주학회 2014 한국항공우주학회 학술발표회 논문집 Vol.2014 No.11

본 연구에서는 곤충 모방 날갯짓 비행체가 제어 모멘트를 발생할 수 있는 날갯짓면 변경 장치를 설계하고 검토하였다. 날갯짓 장치는 슬라이더-크랭크와 풀리-줄 메커니즘의 조합을 통하여, 장착된 모터의 회전운동을 큰 날갯짓 운동으로 변경할 수 있도록 설계하였다. 날갯짓면 변경 장치는 좌우 날개의 날갯짓 각도는 동일하게 유지하면서도 좌우 날개의 날갯짓면을 독립적으로 수평면에 대하여 7~10 도 정도 변경할 수 있도록 설계하였다. 이 장치는 각 날개의 공기력 방향을 변경할 수 있게 하여 자세 제어를 위한 제어 모멘트를 발생할 수 있다. In this work, we designed and investigated the stroke-plane-change (SPC) mechanism for control moment generation in our flapping-wing micro air vehicle (MAV). The flapping-wing mechanism was designed to transfer the rotational motion from the installed motor to large flapping wing motions through a combination of the slider-crank and pulleystring mechanisms. The SPC mechanism is able to independently modify the flapping stroke-plane up to 10° in the left and right wings while maintaining the same amplitude of flapping angle just like a real beetle. As a result, the direction of the resultant aerodynamic forces in each wing can be changed to generate suitable control moments for attitude control.

생체 모방 날갯짓 비행체 개발에 필요한 기술적 이슈들

한재흥(Jae-Hung Han),이준성(Jun-Seong Lee),이진영(Jin-Young Lee),이동규(Dong-Kyu Lee) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

This paper addresses key technical issues in the development of bio-inspired flapping-wing aircrafts. 350 million years of adaptation of nature's flyers deliver us the insights for optimal solutions of How to make artificial flappers fly. However the complexities of flapping-wing motions and aerodynamics cause the difficulties of systematic development of flapping-wing aircrafts. Even though some studies have been performed for the hypothesis of high lift mechanism of flapping-wings and the principles of nature's flyers' flight principle, we do not have well-established design procedures to assemble a stable and controllable flapping-wing aircraft. Hereby we introduce some key technology issues such as optimal flapping-wing and flight controller designs to develop artificial flappers.

Parametric analysis of an oscillating wing energy harvester with a trailing edge flap

Maqusud Alam,손창현 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.7

This study investigated the optimal energy harvesting conditions of an oscillating wing with a trailing edge flap for various parameters such as flap length and maximum wing and flap pitch angles. Numerical simulations were performed for flap lengths ranging from 20 % to 70 % of the chord length (c). The maximum wing pitch angle varied from 40° to 75°, whereas the maximum flap pitch angle varied from 15° to 60°. Results show that the power output performance of a large flap is higher than that of a short flap. This is because the incoming fluid is deflected relatively more vertically by a large flap than by a short flap at the same maximum wing and flap pitch angles. Consequently, the momentum change is enhanced in the direction of the heaving motion, which eventually improves the power output performance. In addition, the camber of the wing increases with flap length, leading to an increase in incoming fluid velocity on the leeward surface of the wing. This caused a decrease in leeward surface pressure for large flaps, resulting in an increased pressure difference on the wing surfaces, which assisted in enhancing the heaving force and power. The maximum power output was obtained at a maximum wing pitch angle of 70° for a flap length 20 % of c, and it was reduced to 45° for a flap length 70 % of c. However, the optimum maximum flap pitch angle varied between 35° and 45° for varying flap lengths. The power output and efficiency were improved by around 27 % and 21 %, respectively, compared with an oscillating wing without a flap, and this was achieved for a flap length 60 % of c with the maximum wing and flap pitch angles of 50° and 45°, respectively.