• Coupled systems mechanics
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• 제5권4호
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• pp.329-340
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• 2016

The trigonal shape memory alloys (SMAs) have a great potential to be utilized as the applications with special purposes, such as actuators with high operation frequency. Most studies on the trigonal microstructures typically focus on the well-known classic herringbone pattern, but many other patterns are also possible, such as non-classic herringbone, toothbrush and checkerboard patterns. In the current work, a systematic procedure is developed to find all possible laminate twin microstructures by using geometrically linear compatibility theory. The procedure is verified by SEM images with the information of crystallographic axes of unitcells obtained by EBSD, showing good agreement. Many interesting trigonal R-phase patterns are found in the specimen. Then, their incompatibility are analyzed with nonlinear compatibility theory. The relationship between such incompatibility and the likelihood of occurrence of the microstructures is revealed. The current procedure is rapid, computationally efficient and sufficiently general to allow further extension to other crystal systems and materials.

• 한국공작기계학회논문집
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• 제18권2호
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• pp.228-233
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• 2009

An ultra-precision stage is used in many industrial areas such as precision machine tools or semiconductor apparatus. These stages used to be driven by piezoelectric actuators in order to obtain ultra precision positioning resolution. Piezoelectric actuator can be moved fast in nanometer resolution. However, it has relatively large non-linear characteristics like hysteresis and creep curve. Although several kinds of control techniques have been developed, controller design method is still complicated. In this paper fuzzy control rules are developed intuitively. In order to verify the performance a series of experiments were conducted and the results were compared with those of the PID controller case.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 추계학술대회 논문집
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• pp.256-258
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• 2003

This paper deals with the development of the PMSM(Permanent magnet synchronous motor) system for the electrical actuator, For the high control performance and reliability of PMSM, accurate information of rotor position is essential. Most of PMSM for the position control use the encoder or resolver for the information of rotor position. But these are very expensive. So, in this paper, using of the magnetic and linear hall-effect sensor is proposed. It can reduce the cost of motor systems and get the good performance of PMSM control.

• 한국정밀공학회지
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• 제27권5호
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• pp.102-111
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• 2010

This paper presents a design of seat mechanism for multi-postures controllable wheelchair. The possible seat postures are reclining, tilting, standing, which are controlled by four seat mechanisms using four linear actuators. The seat mechanisms designed in this study are reclining, tilting, forward-tilting, and elevation mechanism. Three postures except standing are controlled by corresponding mechanisms, but the standing posture is performed by combination of the reclining and the forward-tilting mechanism. Posture control system is composed of PID controllers and a planner to determine a feasible posture based on a posture transition diagram. Simulation results show that the seat mechanism and its control system are applicable to a multi-postures controllable wheelchair.

• 한국정밀공학회지
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• 제22권7호
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• pp.102-111
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• 2005

In this paper, we address a position control for a parallel stage, which is levitated and driven by electric magnetic force. This consists of a levitating object (called platen) with 4 permanent magnetic linear synchronous motors in parallel. Each motor generates vertical force for suspension against gravity and propulsion force horizontally as well. This stage can generate six degrees of freedom motion by the vertical and horizontal force. A dynamic equation of the stage system is derived based on Newton-Euler method and it's special Jacobian matrix describing a relation between the limited velocity and Cartesian velocity is done. There are proposed two control methods for positioning which are Cartesian space controller and Actuator space controller. The control performance of the Cartesian space controller is better than the Actuator space controller in task space trajectory while the Actuator space controller is simpler than the Cartesian space controller in controller realization.

• 한국정밀공학회지
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• 제19권9호
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• pp.179-185
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• 2002

Solid state deformation of PZT is effective for the micron scale displacement. Inch-worm gets large linear displacement by incrementally summing displacements of PZT actuators. Dynamic stiffness of inch-worm is generally low compared to its driving condition due to the small size and light weight of inch-worm. Mechanical vibration induced by low stiffness may degenerate the motion accuracy of the inch-worm. In this paper, dynamic characteristics of the inch-worm are modeled by using the frequency domain curve fitting based on the experimental frequency response function. SMC (sliding mode control) is examined for motion control of the inch-worm. Simulation and experimental results show that the inch-worm with SMC scheme is feasible for the precise displacement device.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.433-438
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• 2003

In this paper we explore the effectiveness of a magnetostrictive actuator(MSA) as a structural control device. A series of numerical and experimental tests are carried out with a simple aluminum beam only supported at each end by the actuator. After the equation of motion of the controlled system is obtained by the finite element method, a model reduction is performed to reduce the numbers of degree of freedom. A linear quadratic feedback controller is realized on a real-time digital control system to damp the first four elastic modes of the beam. Through some tests, we confirmed the possibility of this actuator for controlling beam-like structures.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 학술대회 논문집 전문대학교육위원
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• pp.30-32
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• 2001

Thomson's jumping ring was first exhibited by Elihu Thomson in 1887 and modified to include the floating variation by John A. Fleming in 1890. This vivid demonstration of electromagnetic induction is still used in physics classrooms to illustrate Faraday's and Lenz's laws and is the basis for linear actuators for sorvo-mechanical purpose as well as induction heating and rail guns. The jumping ring apparatus of the type described in this study is used to demonstrate and educate the effects of electromagnetic induction. To verify control algorithm, a sensor system and a data control/measurement system is required. The sensor system consist of photo-interrupted and encode circuit which is designed to take voltage according to the position of ring.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• 제5권1호
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• pp.46-52
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• 2002

A robust nonlinear observer, utilizing the sliding mode concept, is developed for the dynamic positioning of ships. The observer provides the estimates of linear velocities of the ship and bias from slowly varying environmental loads. It also filters out wave frequency motion to avoid wear of actuators and excessive fuel consumption. The main advantage of the proposed observer is in its robustness. Especially, the observer structure with a saturation function makes the proposed observer robust against neglected nonlinearties, disturbances and uncertainties. Since the mathematical model of DP ships is difficult to obtain and includes uncertainties and disturbances, it is very important for the observer to be robust. A nonlinear output feedback controller is derives based on the developed observer using the observer backstepping technique, and the global stability of the observer and control law is shown by Lyapunov stability theory.. A set of simulation was carried out to investigate the performance of the proposed observer for dynamic positioning of ships.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.2849-2850
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• 2000

We developed an automatic 3D inspection system. The system consists of two parts one includes hardwares such as actuators. linear scales and a probe. etc. the other involves softwares for management and control of the system. Compared with existing 3D measurement systems. this system achieved automatically the inspection. This automatic inspection makes the system have some advantages to reduce a measurement time and to be easily used by operators.