• Journal of Mechanical Science and Technology
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• 제20권1호
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• pp.66-75
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• 2006

A modeling method for the modal analysis of rotating beam structures having complex configurations employing multi-reference frames is presented in the present study. In most structural analysis methods, single reference frame is employed for the modal analysis. For simple structures such as single beam or single plate, the method of employing single reference frame usually provides rapidly converging accurate results. However, for general structures having complex configurations, such a method provides slowly converging, and often erroneous, results. In the present study, the effects of employing multi-reference frames on the convergence and the accuracy of the modal analysis of rotating beam structures having complex configurations are investigated.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권2호
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• pp.189-195
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• 2005

This paper presents a new velocity estimation strategy for a non-salient permanent magnet synchronous motor drive without high frequency signal injection or special PWM pattern. This approach is based on the d-axis current regulator output voltage of the drive system, which contains the rotor position error information. The rotor velocity can be estimated through a rotor position tracking PI controller that controls the position error at zero. For zero and low speed operation, the PI gain of the rotor position tracking controller has a variable structure according to the estimated rotor velocity. Then, at zero speed, the rotor position and velocity have sluggish dynamics because the varying gains are very low in this region. In order to boost the bandwidth of the PI controller during zero speed, the loop recovery technique is applied to the control system. The PI tuning formulas are also derived by analyzing this control system by frequency domain specifications such as phase margin and bandwidth assignment.

• Proceedings of the KIEE Conference
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• 대한전기학회 2008년도 심포지엄 논문집 정보 및 제어부문
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• pp.248-250
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• 2008

본 논문은 GP(Genetic Programming)을 이용한 4족 보행 로봇의 새로운 걸음새 생성 방식에 대해 소개한다. 4족 보행로봇의 걸음새 생성문제는 다양한 파라미터를 통시에 최적화해야 하는 매우 어려운 문제이다. 본 논문에서는 GP를 기반으로 관절좌표계에서 로봇의 관절 궤석을 직접 제어하는 방식을 사용한다. 이는 기존의 특정한 형태의 발끝의 자취를 사용하는 방법들에 비해 효율적이며 구조적으로 제한피지 않는 특징을 가진다. 또한, 새로운 트리구조기반의 GP 연산자의 적용을 통해 더 좋은 결과를 얻을수 있었다.

• The Journal of the Korea institute of electronic communication sciences
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• 제4권3호
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• pp.236-242
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• 2009

When two-link flexible arm is rotated about an joint axis, transverse vibration may occur. In this paper, vibration dynamics of flexible robot arm is modeled by using Bernoulli-Euler beam theory and Lagrange equation. Using the fact that matrix $\dot{D}$-2C is skew symmetric, new controllers which have a simplified structure with less computational burden is proposed. Lyapunov stability theory is applied to achieve a stable deterministic nonlinear controller for the regulation of joint angle.

• Journal of Welding and Joining
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• 제34권3호
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• pp.1-5
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• 2016

At present, FSW(friction stir welding) process is being considered as an actual way for production of various industrial products. However FSW process involves high temperature and load on the tool during welding. These are make a difference between FSW machine and general machine tools. From this reason, development of FSW machine needs very careful consideration on stiffness of machine structure, spindle and moving axis including machine control system. In this study authors investigate on the trends of technology development of FSW machine in order to share the information for more extension of FSW technology with related researchers and engineers.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.280-284
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• 1997

In this paper, Nonlinear VSS control based on bang-bang control concept is derived under the assumption that the control input is bounded. We try to derive control algorithm which has almost same performance as the time optimal control. We focus this control scheme on the real implementation of DC motor position controller of flexible link, i.e. we obtain the switching curves from the real data of DC motor system operating under the full maximum and minimum applied voltages. State space is separated into several regions and we set different switching surfaces in each region to reduce chattering problem. The efficiency of the proposed controller is compared with PID controller and it is shown that the controller converges fast than PID controller without chattering. The hybrid controller scheme is also proposed not only to control the position of hub but also to reduce the vibration of end tip of flexible link.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1631-1634
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• 1997

Since surgery is usually a difficult task because of physiological tremor, eye strain, and tremor, contagious and radioactive hazard, it is necessary to develop micro-surgery telerobotic system using improved tools suitable for their specific tasks. Nowadays the growth of interest on microsurgery and medical applications of robotics has been so rapid. But the medical robots are only practical applications of the industrial robots. This paper identifies five general areas of advanced microsurgery based on the current technological background and expertise, and analyzes the motion, tool and accuracy with respect to microsurgery task, and proposed the criteria to evaluate micro-surgical manipulator. The analysis of microusrgery can be heplful to clarify some basic concept and design of micro-surgical manipulators. With these data we will alos propose an efficient in-parallel-platform manipulator having special kinematic structrue structure suitable for microsurgery.

• Journal of Institute of Control, Robotics and Systems
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• 제14권10호
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• pp.1014-1021
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• 2008

This paper proposes an intelligent sliding mode control method for robotic systems with the unknown bound of model uncertainties. In our control structure, the unknown bound of model uncertainties is used as the gain of the sliding controller. Then, we employ the function approximation technique to estimate the unknown nonlinear function including the width of boundary layer and the uncertainty bound of robotic systems. The adaptation laws for all parameters of the self-recurrent wavelet neural network and those for the reconstruction error compensator are derived from the Lyapunov stability theorem, which are used for an on-line control of robotic systems with model uncertainties and external disturbances. Accordingly, the proposed method can not only overcome the chattering phenomenon in the control effort but also have the robustness regardless of model uncertainties and external disturbances. Finally, simulation results for the five-link biped robot are included to illustrate the effectiveness of the proposed method.

• Journal of the Korean Institute of Telematics and Electronics B
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• 제29B권2호
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• pp.60-68
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• 1992

Fuzzy logic rule based controller has many desirable advantages, whih are simple to implement on the real time and need not the information of structure and dynamic characteristics of the system. Thus, nowadays, the scope of the application of the fuzzy logic controller becomes enlarged. But, if the controlled plant is a time-varying/nonlinear system, it is not easy to construct the fuzzy logic rules which need the knowledge of and expert. In this paper, an approach by which the logic control rules can be auto-generated using the genetic algorithm that is known to be very effective in the optimization problem will be proposed and the effectiveness of the proposed approach will be verified by computer simulation of the 2 d.o.f. planner robot.

• International Journal of Control, Automation, and Systems
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• 제3권3호
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• pp.403-410
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• 2005

Nowadays, versatile robots are developed around the world. Novel algorithms are needed for controlling such robots. A 2-Layer fuzzy controller can deal with many inputs as well as many outputs, and its overall structure is much simpler than that of a general fuzzy controller. The main problem encountered in fuzzy control is the design of the fuzzy controller. In this paper, the fuzzy controller is designed by the schema co-evolutionary algorithm. This algorithm can quickly and easily find a global solution. Therefore, the schema co-evolutionary algorithm is used to design a 2-layer fuzzy controller in this study. We apply it to a mobile robot and verify the efficacy of the 2-layer fuzzy controller and the schema co-evolutionary algorithm through the experiments.