A simple smart wing actuator using Ni-Ti SMA

김상헌,조맹효 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.9

One way shape memory effect (SME) is not sufficient in the application of the automatic repeated actuation of the SMA wire because the actuator using SME cannot return to its initial shape after it cools down. In the present study, the two-way SME under residual stress is considered. An actuator using the two-way effect of SMA returns to its initial shape by increasing or decreasing the temperature of SMA under initial residual stress. Using the two-way effect, we manufactured a simple smart wing actuator which consists of the SMA wire and a torsional spring to induce variable residual stresses. The SMA wire after the specific training procedure in order for the actuator to be used for the repeated actuations without performance deteriorations in the specified actuation requirements was used. The simple smart wing actuator has been tested for repeated actuations in still-air as an environmental thermal condition for the practical aspect of its usage. The characteristics of actuator behavior according to operation thermal cycle duration time, i.e., the response characteristics for rapid actuation were investigated. By the application of the simple smart wing actuator using the SMA wire, SMA shows novel performance in repeated actuations.

형상기억합금을 이용한 더블 엑추에이터의 수치해석

김상헌(Sanghaun Kim),조맹효(Maenghyo Cho),김철(Cheol Kim) 한국항공우주학회 2004 韓國航空宇宙學會誌 Vol.32 No.2

잔류응력 하에서 양방향 형상기억효과를 이용하면 온도를 올리거나 내림에 의해서 피구동 구조물이 최초의 형상으로 되돌아간다. 본 연구에서 형상기억합금(SMA)의 열-기계적 구성방정식을 이용하여 잔류응력 하에 놓인 두개의 형상기억합금 선을 이용한 구조물의 형상변형에 관한 수치해석을 수행하였다. 본 연구에서 수행된 수치 시뮬레이션 결과를 통해 엑추에이터 장치는 효과적인 반복구동에 적합함을 알 수 있었다. 본 연구에 사용된 해석방법은 보다 다양하고 실제적인 SMA 작동기의 해석에 확장 적용될 수 있다. A structure using the two-way shape memory effect(TWSME) returns to its initial shape by increasing or decreasing temperature under an initially residual stress. Through the thermo-mechanical constitutive equation of shape memory alloy(SMA) proposed by Lagoudas et αl., we simulated the structure with two SMA wires attached at the tip under the initially given residual stress. Through the numerical results conducted in the present study, the actuator device was suitable for repeated actuation efficiently. The simulation algorithm which proposed in the present study can be applied extensively to the analysis of the SMA-actuators in practical applications.

A SMA-based actuation system for a fish robot

Le, Chan Hoang,Nguyen, Quang Sang,Park, Hoon Cheol Techno-Press 2012 Smart Structures and Systems, An International Jou Vol.10 No.6

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.

A SMA-based actuation system for a fish robot

Chan Hoang Le,Hoon Cheol Park,박훈철 국제구조공학회 2012 Smart Structures and Systems, An International Jou Vol.10 No.6

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 20o, 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.

Neuralnetwork based control of SMA actuator for the active catheter

Hyo Jik Lee,Jung Ju Lee,Dong Soo Kwon,Yong San Yoon 한국과학기술원 인간친화 복지 로봇 시스템 연구센터 2001 International Journal of Assistive Robotics and Me Vol.2 No.2

  In this paper, the dynamics model of the SMA actuator which was used for the control of bending the angle of a catheter tip was studied. It was shown analytically that the bending angle control of the active catheter was possible by using the resistance feedback control of SMA actuator. Also, we proved the resistance feedback control was possible experimentally but the precise control is somewhat difficult to achieve. This resistance control strategy is quite advantageous to the space limited structure like the active catheter. For the nonlinear implicit SMA actuator, we conducted the neural network based control system design and compared it with a conventional PID controller.

Ultimate load and release time controllable non-explosive separation device using a shape memory alloy actuator

탁원준,이민수,김병규 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.5

This paper describes a newly designed ultimate load and release time controllable non-explosive separation device which is activated by a spring-type shape memory alloy (SMA) actuator. This device is comprised of a separation mechanism consisting of a deformation module, a blocker, the housing, two release springs and a spring-type SMA actuator. Through a theoretical approach, the ultimate load of the separation device and the required force to deform the deformation module according to the thickness of the deformation module are investigated. Based on theoretical results, the specifications of an SMA actuator to deform the deformation module are determined. In order to validate theoretical result, we manufactured a separation device which has a 1mm thickness of deformation module. Subsequently,the release time test, preload test, ultimate load test, and shock test are performed respectively. As a result, the release time with 30 W of power input is 55 sec. It actuates reliably under 150 N of preload and generates a maximum shock of -11.09 G when the diameter of the SMA wire is 1.75mm. The maximum ultimate-load for 1mm thickness of aluminum deformation module is 1,510N. Conclusively,satellite designers can select proper specification such as the ultimate load, shock level and release time according to satellite requirements by simply changing the thickness of the deformation module.

Curved shape memory alloy-based soft actuators and application to soft gripper

Rodrigue, H.,Wang, W.,Kim, D.R.,Ahn, S.H. ELSEVIER (APPLIED SCIENCE) 2017 COMPOSITE STRUCTURES -BARKING THEN OXFORD- Vol.176 No.-

The performance of shape-memory alloy (SMA)-based soft actuators depends largely on the configuration of the cross-section of the actuator. A shape memory alloy-based curved bending actuator manufactured by double casting is introduced in this work. Curved actuators are capable of larger maximum bending angles with the same cross-section configuration as a straight actuator, and both the design method and the casting method proposed in this work are novel for this type of actuator. The effect of the initial bending angle due to the curvature of the actuator and of non-uniform initial curvatures on the maximum bending angle was tested. A model based on the thermoconstitutive model of SMA with a geometrical analysis of the deformation of the actuator was used to estimate the effect of the initial curvature on the maximum bending angle of the actuator. Finally, multiple curved actuators were implemented as a simple gripper and the lifting force of straight and curved actuators were compared, and the curved gripper has a lifting force nearly three times larger than the straight gripper. This type of concept can be used to tailor the force, deformed shape and maximum deformation of SMA actuators.

Review of Biomimetic Underwater Robots Using Smart Actuators

추원식,안성훈,이경태,송성혁,한민우,이장엽,김형수,김민수,박용재,조규진 한국정밀공학회 2012 International Journal of Precision Engineering and Vol.13 No.7

In this paper, biomimetic underwater robots built using smart actuators, e.g., a shape memory alloy (SMA), an ionic polymer metal composite (IPMC), lead zirconate titanate (PZT), or a hybrid SMA and IPMC actuator, are reviewed. The effects of underwater environment were also considered because smart actuators are often affected by their external environment. The characteristics of smart actuators are described based on their actuating conditions and motion types. Underwater robots are classified based on different swimming modes. We expanded our classification to non-fish creatures based on their swimming modes. The five swimming modes are body/caudal actuation oscillatory (BCA-O), body/caudal actuation undulatory (BCA-U), median/paired actuation oscillatory (MPA-O), median/paired actuation undulatory (MPAU),and jet propulsion (JET). The trends of biomimetic underwater robots were analyzed based on robot speed (body length per second, BL/s). For speed per body length, robots using an SMA as an actuator are faster than robots using an IPMC when considering a similar length or weight. Robots using a DC motor are longer while their speeds per body length are similar, which means that robots using smart actuators have an advantage of compactness. Finally, robots (using smart actuators or a motor) were compared with underwater animals according to their speed and different swimming modes. This review will help in setting guidelines for the development of future biomimetic underwater robots, especially those that use smart actuators.

Morphing Wing Mechanism Using an SMA Wire Actuator

Woo-Ram Kang,Eun-Ho Kim,Min-Soo Jeong,In Lee,Seok-Min Ahn 한국항공우주학회 2012 International Journal of Aeronautical and Space Sc Vol.13 No.1

In general, a conventional flap on an aircraft wing can reduce the aerodynamic efficiency due to geometric discontinuity. On the other hand, the aerodynamic performance can be improved by using a shape-morphing wing instead of a separate flap. In this research, a new flap morphing mechanism that can change the wing shape smoothly was devised to prevent aerodynamic losses. Moreover, a prototype wing was fabricated to demonstrate the morphing mechanism. A shape memory alloy (SMA) wire actuator was used for the morphing wing. The specific current range was measured to control the SMA actuator. The deflection angles at the trailing edge were also measured while various currents were applied to the SMA actuator. The trailing edge of the wing changed smoothly when the current was applied. Moreover, the deflection angle also increased as the current increased. The maximum frequency level was around 0.1 Hz. The aerodynamic performance of the deformed airfoil by the SMA wire was analyzed by using the commercial program GAMBIT and FLUENT. The results were compared with the results of an undeformed wing. It was demonstrated that the morphing mechanism changes the wing shape smoothly without the extension of the wing skin.

Robust Shape Control of Two SMA Actuators Attached to a Flexible Beam Based on DK Iteration

Farshid Alambeigi,Ali Zamani,Gholamreza Vossoughi,Mohammad Reza Zakerzadeh 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10

There has been great demand for shape memory alloy (SMA) wires as actuators for shape control of flexible structures. The experimental setup of this study consists of a flexible beam actuated by two active SMA actuators. The input applied to the SMA actuator in this setup is electrical current while the output is the strain or position. To control strain of the actuator, the SMA wire is heated resistively in order to reach the desired temperature calculated by inverse of the phenomenological model. In heating the SMA wire resistively, the controllable quantity is the heat input to the wire via an applied current. In controller design, changes of physical properties of SMA wires and the surrounding air due to temperature change must be taken into consideration. This adds uncertainty to the presented model. Furthermore, both wires must approach the desired temperature while maintaining the same temperature history. Moreover, a suitable shape control requires overdamped response. A 2-DOF robust controller is designed in this study in order to achieve all the above requirements. The robust controller by the DK iteration method is designed after modeling of the system uncertainties. Required simulations are performed for evaluation of the controller. Obtained results show the ability of controller against time variant uncertainties.