• 한국콘텐츠학회논문지
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• 제14권3호
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• pp.451-462
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• 2014

본 연구에서는 지방부 간선 또는 지선 축에서 효과적으로 사용 가능한 연동형 반감응 신호제어 알고리즘을 개발하고 이를 평가하였다. 연동형 반감응 신호제어에 대한 모의실험 결과를 살펴보면, 주 부 도로의 교통량 차이가 커질수록 연동형 반감응 신호제어의 지체가 최적화된 고정식 신호제어에 비해 감소하는 것을 확인하였다. 그러나 주부도로의 교통량이 같거나 전체 교통량이 많아지면 최적화된 고정식 신호제어의 지체가 더 낮게 나타났으며, 횡단 보행량이 많아질수록 차량 지체가 증가하는 것으로 확인되었다. 따라서 연동형 반감응 신호제어는 차량 교통량이 일정수준 이하인 곳에 적용하되, 횡단 보행량을 고려하여 적용지역을 선별해야 할 것이다.

• International Journal of Ocean System Engineering
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• 제1권3호
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• pp.120-135
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• 2011

This paper proposes a model based trajectory tracking control scheme for under-actuated underwater robotic vehicles. The difficulty in stabilizing a non-linear system using smooth static state feedback law means that the design of a feedback controller for an under-actuated system is somewhat challenging. A necessary condition for the asymptotic stability of an under-actuated vehicle about a single equilibrium is that its gravitational field has nonzero elements corresponding to non-actuated dynamics. To overcome this condition, we propose a continuous time-varying control law based on the direct estimation of vehicle dynamic variables such as inertia, damping and Coriolis & centripetal terms. This can work satisfactorily under commonly encountered uncertainties such as an ocean current and parameter variations. The proposed control law cancels the non-linearities in the vehicle dynamics by introducing non-linear elements in the input side. Knowledge of the bounds on uncertain terms is not required and it is conceptually simple and easy to implement. The controller parameter values are designed using the Taguchi robust design approach and the control law is verified analytically to be robust under uncertainties, including external disturbances and current. A comparison of the controller performance with that of a linear proportional-integral-derivative (PID) controller and sliding mode controller are also provided.

• 대한교통학회지
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• 제29권2호
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• pp.111-121
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• 2011

기존 루프검지기를 이용한 반감응 신호제어는 한정된 검지영역으로 인해 대기 차량수에 따른 초기녹색시간의 산정이 불가능하며, 좌회전 베이 측면에서 진입하는 차량과 중차량 및 U턴 차량으로 인해 비합리적인 현시 조기종결문제가 발생할 수 있다. 따라서 본 연구에서는 감응현시의 초기녹색시간을 대기 차량수에 맞게 최적화하고, 검지영역 내 차량소거 여부를 파악함으로써 현시의 연장 및 조기종결을 결정하는 좌회전 감응식 신호제어전략을 개발하였다. 차량의 검지를 위해 영상검지기의 Video Image Tracking기술을 이용하였으며, 영상검지영역은 목적에 맞게 Zone in Zone방식의 3개 영역으로 구분하여 Zone1은 차량의 존재유무 파악, Zone2는 대기 차량수 파악, Zone3는 통과 차량수 파악의 기능을 수행하도록 설계하였다. CORSIM을 이용한 본 좌회전 감응제어의 현장 적용성 평가 결과, 정주기 제어, 반감응 제어(1), 반감응 제어(2)에 비해 Control delay가 각각 23.10%, 15.06%, 4.34% 감소하였으며, Queue time은 36.24%, 20.10%, 7.42%, Total time은 14.36%, 7.02%, 2.96% 감소하여 운영효율이 향상된 것으로 나타났다. 또한, 직진과 좌회전 v/c비에 따른 적용성 평가 결과, 직진교통량이 포화상태에 근접할수록, 좌회전 교통량이 적을수록 개선효과 큰 것으로 나타났다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.323-326
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• 1997

Conventional robots actuated by motors with the speed reducer such as harmonic drive had weakness in delivering loads, pressing, grinding, and cutting jobs. To overcome this, the developer a new type of robot actuated by the ball screw. The robot is an articulated shape, which is composed of four axes. The base axis is actuated similarly with conventional robot, but the others are actuated by four bars mechanism composed of the ball screw. We setup the dynamics model of the robot. The robot has parameter uncertainties and nonlinearlity due to the ball screw actuator. To coordinate the robot, we applied sliding-mode control.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제15권4호
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• pp.240-250
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• 2015

The development of the control algorithms for under-actuated systems is important. Decoupled sliding mode control has been successfully employed to control under-actuated systems in a decoupling manner with the use of sliding mode control. However, in such a control scheme, the system functions must be known. If there are uncertainties in those functions, the control performance may not be satisfactory.In this paper, the direct adaptive fuzzy sliding mode control is employed to control a class of under-actuated uncertain systems which can be regarded as a combination of several subsystems with one same control input. By using the hierarchical sliding control approach, a sliding control law is derived so as to make every subsystem stabilized at the same time. But, since the system considered is assumed to be uncertain, the sliding control law cannot be readily facilitated. Therefore, in the study, based on Lyapunov stable theory a fuzzy compensator is proposed to approximate the uncertain part of the sliding control law. From those simulations, it can be concluded that the proposed compensator can indeed cope with system uncertainties. Besides, it can be found that the proposed compensator also provide good robustness properties.

• 제어로봇시스템학회논문지
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• 제18권1호
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• pp.42-46
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• 2012

A simple and accurate depth estimation algorithm for an IBVS (Image-Based Visual Servoing) is presented. Specifically, this algorithm is useful for under-actuated systems such as visual-guided quadrotor UAVs (Unmanned Aerial Vehicles). Since the image of a marker changes with changing pitch and roll angles of quadrotor, it is difficult to estimate depth. The proposed algorithm compensates a shape of the marker, so that the system acquire more accurate depth information without complicated processes. Also, the roll and pitch channels are decoupled so that the IBVS algorithm can be used in an under-actuated quadrotor system.

• Nuclear Engineering and Technology
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• 제31권6호
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• pp.1-7
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• 1999

An innovative concept for a passive reactor shutdown system, so called self-actuated shutdown system(SASS), is inevitably required for the inherent safety in liquid metal reactor, which is designed with the totally different concept from the usual reactor shutdown system in LWR. SASS using Curie point electromagnet(CPEM) was selected as the passive reactor shutdown system for KALIMER (Korea Advanced Liquid MEtal Reactor). A mock-up of the SASS was designed, fabricated and tested. From the test it was confirmed that the mockup was self-actuated at the Curie point of the temperature sensing material used in the mockup. An articulated control rod was also fabricated and assembled with the CPEM to confirm that the control rod can be inserted into core even when the control rod guide tube is deformed due to earthquake. The operability of SASS in the actual sodium environment should be confirmed in the future. All the design and test data will be applied to the KALIMER design.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.292-295
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• 2001

Conventional robots actuated by motors with the speed reducer such as harmonic drive had weakness in delivering loads, pressing, grinding, and cutting jobs. To overcome this, a new type of robot actuated by the ball screw was proposed. The ball screw is actuated by using four bar mechanism. The dynamics model of the robot was set up. The robot has parameter uncertainties and nonlinearlity due to the ball screw actuator. To coordinate the robot, the sliding-mode control was applied.

• Transactions on Control, Automation and Systems Engineering
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• 제4권1호
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• pp.78-83
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• 2002

In this paper, we propose a sliding mode controller for a robot manipulator with passive joints. A robot manipulator with passive joints which are not equipped with any actuators is a kind of underactuated system. Underactuated systems have some advantages compared to fully-actuated ones. For example, they weigh less and consume less energy because they have smaller number of components than fully-actuated ones. However the control of an underactuated manipulator is much more difficult than that of fully- actuated robot manipulator. In this paper a complex dynamic model of a manipulator with passive joints is manipulated for sliding mode control. Sliding mode controllers are designed for this complex system and the stability of the controllers is proved mathematically. Finally a simulation for this control system is executed for evaluating the effectiveness of the designed sliding mode controller.

• 제어로봇시스템학회논문지
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• 제5권4호
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• pp.385-393
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• 1999

An open loop vibrational control for an underactuated mechanical system with amplitude and frequently modulation is investigated. Since there is no direct external input to an unactuated joint, the dynamic coupling between the actuated and unactuated joints is utilized for controlling the unactuated joint. Feedback linearization has been performed to incorporate fully the known nonlinearities of the underactuated system considered. The actuated joints are firstly positioned to their desired locations, and the periodic oscillatory inputs are applied to the actuated joints to move the remaining unactuated joints to their target positions. The amplitudes and frequencies of the vibrations introduced are determined through averaging analysis. A systematic way of obtaining an averaged system for the underactuated system via a coordinate transformation is developed. A control design example of 2R planer manipulator with a free joint with no brake is provided.