• 대한전기학회논문지:시스템및제어부문D
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• 제50권7호
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• pp.313-317
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• 2001

This paper proposed a fuzzy logic cross coupled controller which can enhance the path tracking performance of optically guided AGV(Automated Guided Vehicle). The AGV follows the guide path, it cannot be avoid the deviation from the path due to the inevitable error and the deviation must be corrected. Optically guided AGV used in industrial area is controlled by On-Off controller generally, the experimental AGV has three optical sensors in front body. In this structure, we could not know the leaving distance accurately and steering angle from the guided line, so AGV could not be controlled properly with conventional controller in the case of increasing or decreasing velocity. If we mount additional sensors the AGV, we could know the leaving distance and steering angle from the guided line and proper error compensating methode can be applied. But because cost of sensors are high, the cost of total system is increasing. So, in this paper, to improve the tracking performance of AGV which has the minimum number of sensors and fuzzy logic cross coupled controller is proposed. Some simulations and experimental results are presented to illustrate the performance of the proposed controller.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.786-791
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• 2003

This paper proposes an adaptive control algorithm for nonholonomic mobile robots with unknown parameters and the proposed control method is used in numerical simulations for applying to a practical twowheeled welding mobile robot(WMR). The proposed adaptive controller to track an arbitrary given welding path is designed by using back-stepping technique and is derived for a nonlinear model under the assumption such that the system parameters are partially known. Moreover, the proposed adaptive control system is stable in the sense of Lyapunov stability. Inertia moments of system are considered to be unknown parameters and their values can be estimated simply by using update laws proposed in an adaptive control scheme of this research. The simulation results are provided to show the effectiveness of the accurate tracking capability of the proposed controller for two-wheeled welding mobile robot with a smooth curved reference welding path.

• 제어로봇시스템학회논문지
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• 제13권2호
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• pp.140-146
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• 2007

This paper demonstrates the development of a mobile robot for patrol. We fuse differential GPS, angle sensor and odometry data using the framework of extended Kalman filter to localize a mobile robot in outdoor environments. An important feature of road environment is the existence of curbs. So, we also propose an algorithm to find out the position of curbs from laser range finder data using Hough transform. The mobile robot builds the map of the curbs of roads and the map is used fur tracking and localization. The patrol robot system consists of a mobile robot and a control station. The mobile robot sends the image data from a camera to the control station. The remote control station receives and displays the image data. Also, the patrol robot system can be used in two modes, teleoperated or autonomous. In teleoperated mode, the teleoperator commands the mobile robot based on the image data. On the other hand, in autonomous mode, the mobile robot has to autonomously track the predefined waypoints. So, we have designed a path tracking controller to track the path. We have been able to confirm that the proposed algorithms show proper performances in outdoor environment through experiments in the road.

• 한국컴퓨터정보학회논문지
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• 제13권7호
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• pp.67-73
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• 2008

본 논문에서는 무선 센서 노드의 실내 위치 추적 시스템을 제안한다. 위치 추정에 사용하는 센서 값으로 RF 인터페이스의 수신 신호 강도 (RSSI)를 사용한다. 이동 노드를 부착한 사용자와 실내에 고정된 다수의 고정 노드의 신호 강도를 수신하여 사용자의 위치를 결정한다. 제안한 시스템은 측정에 의한 2.4GHz log-normal path loss 모델의 수신강도와 유클리드 거리 계산 방법과 신호 강도를 결합한다. 실험결과를 통해서 1.3m 이내의 오차로 위치를 추정함을 확인하였다.

• Journal of Positioning, Navigation, and Timing
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• 제2권2호
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• pp.123-130
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• 2013

Autonomous agricultural machines that are operated in small-scale farmland frequently experience turning and changes in direction. Thus, unlike when they are operated in large-scale farmland, the steering control systems need to be controlled precisely so that travel errors can be minimized. This study aims to develop a control algorithm for improving the path tracking performance of a steering system by analyzing the effect of the setting of the waypoint, which serves as the reference point for steering when an autonomous agricultural machine moves along a path or a coordinate, on control errors. A simulation was performed by modeling a 26-hp tractor steering system and by applying the equations of motion of a tractor, with the use of a computer. Path tracking errors could be reduced using an algorithm which sets the waypoint for steering on a travel path depending on the radius of curvature of the path and which then controls the speed and steering angle of the vehicle, rather than by changing the steering speed or steering ratio which are dependent on mechanical performance.

• Journal of Construction Engineering and Project Management
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• 제6권2호
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• pp.30-39
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• 2016

This research presents the development of a self-governing mobile robot navigation system for indoor construction applications. This self-governing robot navigation system integrated robot control units, various positioning techniques including a dead-reckoning system, a UWB platform and motion sensors, with a BIM path planner solution. Various algorithms and error correction methods have been tested for all the employed sensors and other components to improve the positioning and navigation capability of the system. The research demonstrated that the path planner utilizing a BIM model as a navigation site map could effectively extract an efficient path for the robot, and could be executed in a real-time application for construction environments. Several navigation strategies with a mobile robot were tested with various combinations of localization sensors including wheel encoders, sonar/infrared/thermal proximity sensors, motion sensors, a digital compass, and UWB. The system successfully demonstrated the ability to plan an efficient path for robot's movement and properly navigate through the planned path to reach the specified destination in a complex indoor construction site. The findings can be adopted to several potential construction or manufacturing applications such as robotic material delivery, inspection, and onsite security.

• 한국정보통신학회논문지
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• 제18권4호
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• pp.906-912
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• 2014

물고기 로봇 연구는 몸체 및 꼬리 관절 궤적의 크기나 주파수의 크기에 따른 로봇의 추력 비교 또는 꼬리 관절 궤적을 적절한 함수로 선정하여 물고기 로봇의 빠른 회전 등과 관련된 연구가 주를 이루고 있다. 본 연구에서는 물고기 로봇이 추력을 받아 앞으로 유영할 경우, 로봇의 몸체 및 꼬리 관절이 사인파와 같이 좌, 우로 요동치며 움직이므로 피드백 제어를 행하기 어렵다. 따라서 물고기 로봇의 경로에 기초한 가상의 위치를 검출하고, 검출된 위치를 사용하여 주어진 경로 위의 예견 점(look-ahead point)을 기준으로 방향 오차를 정의하여 물고기 로봇이 경로를 추종하도록 제어기를 설계하였다. 모의실험 결과 제안된 방법의 유용성을 확인할 수 있었다.

• International Journal of Control, Automation, and Systems
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• 제1권1호
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• pp.35-42
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• 2003

This paper proposes a simple, robust, nonlinear controller based on Lyapunov stability for tracking the reference welding path and velocity of a two-wheeled welding mobile robot (WMR). The system has three degrees of freedom including two wheels and one torch slider. Torch slider motion is used for faster tracking because the welding speed is very slow. Control law is obtained from the Lyapunov control function to ensure the asymptotical stability of the system. The controller has three free parameters for adjusting the performance of the controlled system. A simple way of measuring the errors using two potentiometers is introduced. The effectiveness of the proposed controller is shown through simulation results.

• 제어로봇시스템학회논문지
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• 제9권6호
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• pp.478-488
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• 2003

A guidance scheme that is suitable for controlling the aircraft flight path is proposed. The concept of miss distance which is commonly used in the missile guidance laws, and Lyapunov stability theorem are effectively combined to obtain the aircraft's trajectory-tracking guidance law. Guidance commands are given in terms of speed and flight path angles, but they perfectly reflect any position and velocity errors between real aircraft trajectory and reference one. The proposed guidance law is easily integrated into the existing flight control system. The new guidance law was extensively tested with various mission scenarios and the fully nonlinear 6-DOF aircraft model. Furthermore, the new guidance law was compared with previous guidance schemes in nonlinear simulation. Results from the numerical simulation show that the proposed guidance law yields better performance than previous ones.

• 항공우주기술
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• 제11권2호
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• pp.140-148
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• 2012

자율 주행을 위해 주행 지도, 위치 추적 및 목적지까지의 최단 경로 설정 연구가 필요하다. 특히 실내에서는 GPS 신호를 수신 받을 수 없기 때문에 이미지 프로세싱과 같은 방법을 통해 현재 위치를 인식하고 3차원 지도를 생성해야 한다. 본 논문에서는 Depth 카메라인 키넥트를 이용하여 3차원 지도를 생성하고, 일반 카메라로 촬영한 2차원 이미지를 이용하여 3차원 지도에서 현재 위치를 파악하는 방법에 대해 설명한다. 그리고 지도에서 장애물을 확인하고 단순화하는 방법에 대해서도 설명한다.