• 로봇학회논문지
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• 제12권1호
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• pp.86-93
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• 2017

The Expanded Guide Circle (EGC) method has been originally proposed as the guidance navigation method for improving the efficiency of the remote operation using the sensory information. The previous algorithm is, however, concerned only for the omni-directional mobile robot, so it needs to suggest a suitable one for a mobile robot with non-holonomic constraints. The ego-kinematic transform is a method to map points of $R^2$ into the ego-kinematic space which implicitly represents non-holonomic constraints for admissible paths. Thus, robots with non-holonomic constraints in the ego-kinematic space can be considered as "free-flying object". In this paper, we propose an effective obstacle avoidance method for mobile robots with non-holonomic constraints by applying EGC method in the ego-kinematic space using the ego-kinematic transformation. This proposed method shows that it works better for non-holonomic mobile robots such as differential-drive robot than the original one. The simulation results show its effectiveness of performance.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.468-471
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• 1995

In this paper, we propose a new strategy for a space robot to control its attitude. A space robot is an example of a class of non-holonomic systems, a system of which cannot be stabilized into its equilibria with continuous static state feedbacks even in the case that the system is, in some sense, controllable. Thus, we cannot design stabilizing controllers for space robots using conventional control theories. The strategy presented here transforms the non-holonomic system into a time-state control form, and allows us to make the state of the original system any desired one. In the stabilization, any conventional control theory can be applied. For simplicity, a space robot with a two-link manipulator is considered, and a simulated motion of the controlled system is shown.

• 한국지능시스템학회논문지
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• 제20권3호
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• pp.413-421
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• 2010

본 논문에서는 로봇 축구용 카메라를 사용하는 기존 경로계획의 제한적인 사항을 극복하기 위해서 컬러 인식법에 의한 경로계획방법을 제시한다. 제안된 연구에서는 움직이는 목표물이 스웜로봇과 멀리 있어도 로봇의 직선 시야를 기반으로 동료 로봇을 따라가며, 움직이는 목표물을 추적 할 수 있다. 제안된 포텐셜 필드는 동료 로봇과의 충돌과 장애물과의 충돌을 피하면서 스웜 로봇들이 움직이는 목표물을 향하여 이동하게 한다. 결국, 스웜 로봇들 사이의 시각적 도움에 의해 최종 목표물에 모든 스웜 로봇들이 도달하게 된다. 제안된 방법은 움직이는 파티클, 즉 점 로봇이 아닌 논홀로노믹 제한이 있는 유니 사이클 로봇들을 대상으로 자기 조직화 방법을 제시하기 때문에 실제 하드웨어 적용시 유용하다.

• 로봇학회논문지
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• 제2권3호
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• pp.212-220
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• 2007

This paper proposes a method of avoiding obstacles and tracking a moving object continuously and simultaneously by using new concepts of virtual tow point and fuzzy danger factor for differential wheeled mobile robots. Since differential wheeled mobile robot has smaller degree of freedom to control and are non-holonomic systems, there exist multiple solutions (trajectories) to control and reach a target position. The paper proposes 'fuzzy danger factor' for obstacles avoidance, 'virtual tow point' to solve non-holonomic object tracking control problem for unique solution and three kinds of fuzzy logic controller. The fuzzy logic controller is policy decision controller with fuzzy danger factor to decide which controller's result is more valuable when the mobile robot is tracking a moving object with obstacles to be avoided.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1269-1274
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• 2004

This paper presents a new quantisation algorithm which has the closed-loop form and guarantees the boundness of accumulative error. This algorithm is particularly useful for mobile robot navigation that is usually implemented on embedded systems. If wheel commands of the mobile robot are given by velocity or positional increment at every control instant and quantised due to finite word length of controller's CPU, the quantisation error gets accumulated to causes large position error. Such an error accumulative characteristic is fatal for non wheeled mobile robots or autonomous vehicles with non-holonomic constraint. To solve this problem, we propose a non-error accumulative quantisation algorithm with closed-loop form. We also show it can be extend to a generalized form corresponding to the n-th order accumulation. The boundness of the accumulative quantisation error is investigated by a series of computer simulation. The proposed method is particularly effective to precise navigation control the autonomous mobile robots.

• 제어로봇시스템학회논문지
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• 제6권7호
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• pp.586-593
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• 2000

In this paper we propose a new approach to the autonomous wall-following of wheeled mobile robots using hybrid system reference motion synthesis and generation. The hybrid system approach is in-troduced to the motion control of nonholonomic mobile robots for the indoor navigation problems. In the dis-crete event system the discrete states are defined by the user-defined constraints and the reference mo-tion commands are specified in the abstracted motions. The hybrid control system applied for the non-holonomic mobile robots can combine the motion planning and autonomous navigation with obstacle avoid-ance for the indoor navigation problem. Simulation results show that hybrid system approach is an effective method for the autonomous navigation in indoor environments.

• 한국산학기술학회논문지
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• 제13권12호
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• pp.6034-6039
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• 2012

본 논문에서는 모바일 로봇이 이동함에 있어 경사면을 만났을 경우 이를 극복하여 주행하는 경우가 발생할 수 있는데 이때 모바일 로봇 시스템 자체가 가지고 있는 슬립 문제가 주행을 진행함에 있어서 더욱 심하게 나타날 수 있기에 이를 해결하고 목표점까지의 안전한 직진 주행을 하기위한 모델 적응 퍼지 제어 방법을 기반으로 하는 모바일 로봇의 주행 제어 알고리즘을 제안하고자 한다. 제안하고자 하는 모델 기반 적응 퍼지 제어기의 경우 먼저, 모바일 로봇의 등반 조건을 확인한 후 경사면을 모바일 로봇이 극복 주행을 할 수 있는지를 판단하고 만약 가능하다면 모바일 로봇의 동역학 모델을 포함한 모델 기반 제어기를 설계하여 극복 주행 제어를 하고자 한다. 이러한 경우 모바일 로봇 시스템의 안정성 보장 및 지면 마찰력 그리고 외란 보상 등이 충분히 고려된 제어기 설계가 가능할 것이다. 또한, 설계하고자 하는 제어 기법 중 적응 퍼지 제어 방법의 경우 모바일 로봇의 동특성을 충분히 반영한 모델인 비선형 Non-holonomic 시스템과 모바일 로봇의 슬립 문제 해결 등에 충분히 유용할 것이고 이를 컴퓨터 시뮬레이션을 통해 검증하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.787-792
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• 1991

This paper proposes a steering control algorithm for non-holonomic mobile robots. The steering control algorithm is essential to navigate autonomous vehicles which employ comination of the dead reckoning and absolute sensor system such as a machine vison for detecting landmarks in order to estimate the current location of the mobile robot. The proposed algorithm is based on the minimum time BANG-BANG controller and curvature-continuity curve design method. In the BANG-BANG control scheme we introduce velocity/acceleration limiter to avoid any slippage of driving wheels. The proposed scheme is robot-independent and hence can be applied to various kinds of mobile robot or vehicles. To show the effectness of the proposed control algorithm, a series of computer simulations were conducted for two-wheel driven mobile robot.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 D
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• pp.2473-2475
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• 2001

In trajectory tracking methods, the error values of current position and velocity are compensated to follow the given reference path and velocity. The path tracking for a wheeled mobile robot is treated in this paper. It is very difficult to implement stable trajectory tracking algorithms because mobile robots have kinematically non-holonomic constraints. For solving this problem, a velocity controller is presented in this paper. This velocity controller is designed by a PID controller which could be easily employed. In this case, velocity errors caused by system uncertainties or internal and external disturbances could exist. A neural network is used for compensating the velocity errors. Input variables of this neural network compensator are defined by differences between the velocities of the posture controller and the real velocities of the mobile robot. Simulation results show the effectiveness of the proposed controller.

• 한국정밀공학회지
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• 제30권11호
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• pp.1161-1169
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• 2013

In this paper an omni-directional mobile robot is suggested for educational robot platform. Comparing to other robots, a mobile robot can be easily designed and manufactured due to its simple geometric structure. Moreover, since it is required to have low DOF motion on planar space, fabrication of control system is also simple. In this research, omni-directional wheels were adopted to remove the non-holonomic characteristic of conventional wheels and facilitate control system design. Firstly, geometric structure of a Mecanum wheel which is a most frequently used omni-directional wheel was demonstrated. Then, the organization of the mobile platform was suggested in aspects of mechanism manufacturing and electronic hardware design. Finally, a methodology of control system development was introduced for educational purpose. Due to an intuitive motion generating ability, simple hardware composition, and convenient control algorithm applicability, the omni-directional mobile robot suggested in this research is expected to be a promising educational platform.