• International Journal of Fuzzy Logic and Intelligent Systems
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• 제2권2호
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• pp.100-108
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• 2002

A fuzzy logic for collision avoiding navigation of marine vehicles is proposed in this paper. VFF(Virtual Force Field) method, which is used widely in the field of mobile robots, is modifiel to apply to marine vehicles. The method is named MVFF (Modified Virtual Force Field) mothod. The MVFF consists of the determination of the heading angles far track-keeping mode ($\psi_{ca}$)and collision avoidance mode ($\psi_{ca}$). The operator can choose the pattern of the track-keeping mode in the proposed algorithm. The collision avoidance algorithm can handle static and/or moving obstacles. These functons are implemented using fuzzy logic. Various simulation results verify the proposed alogorithm.

• 한국통신학회논문지
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• 제39C권5호
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• pp.425-432
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• 2014

IEEE 802.11e EDCA(Enhanced Distributed Channel Access)는 서로 다른 AC(Access Category)에 따라서 CW(Contention Window)를 이용하여 Quality-of-Service(QoS)를 지원한다. 그러나 무선 네트워크 환경이 혼잡 (Congested)할 경우 패킷의 충돌 발생 확률을 높일 수 있다는 문제점이 여전히 존재한다. 이를 해결하기 위해 여러 방법들이 제시되었으나 혼잡 네트워크상에서는 동일 우선순위를 가지는 패킷 전송을 위해서 전송 채널을 이용하는 경쟁 과정에서 패킷 충돌(Collision)이 발생할 확률이 여전히 존재한다. 따라서 본 논문에서는 EDCA 포화 상태에서 전송 효율을 높이는 APCA(Advanced Priority Collision Avoidance) 알고리즘을 제안한다. 제안된 알고리즘은 IEEE 802.11e 표준을 기반으로 RTS/CTS (Request to Send / Clear to Send)를 이용하여 패킷 전송 FC(Frame Control) 필드의 예약된 필드(Reserved Field) 비트를 이용하여 데이터 패킷 충돌을 회피하는 것이다. 시뮬레이션의 결과로 제안된 알고리즘이 기존의 EDCA에 비해 패킷 전송 실패율이 감소했음을 보였다. Jain's fairness index를 이용하여 제안된 APCA 알고리즘이 네트워크 혼잡 상황에서 EDCA 방식 보다 공정성을 유지하는 것을 확인하였다.

• International Journal of Control, Automation, and Systems
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• 제2권2호
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• pp.171-181
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• 2004

An autonomous navigation algorithm for marine vehicles is proposed in this paper using fuzzy logic under COLREG guidelines. The VFF (Virtual Force Field) method, which is widely used in the field of mobile robotics, is modified for application to the autonomous navigation of marine vehicles. This Modified Virtual Force Field (MVFF) method can be used in either track-keeping or collision avoidance modes. Moreover, the operator can select a track-keeping pattern mode in the proposed algorithm. The collision avoidance algorithm has the ability to handle static and/or moving obstacles. The fuzzy expert rules are designed deliberately under COLREG guidelines. An extensive simulation study is used to verify the proposed method.

• 자동차안전학회지
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• 제5권2호
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• pp.24-31
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• 2013

This paper describes a coordinated control algorithm for rear-side collision avoidance. In order to assist driver actively and increase driver's safety, the proposed coordinated control algorithm is designed to combine lateral control using a steering torque overlay by Motor Driven Power Steering (MDPS) and differential braking by Vehicle Stability Control (VSC). The main objective of a combined control strategy is twofold. The one is to prevent the collision between the subject vehicle and approaching vehicle in the adjacent lanes. The other is to limit actuator's control inputs and vehicle dynamics to safe values for the assurance of the driver's comfort. In order to achieve these goals, the Lyapunov theory and LMI optimization methods has been employed. The proposed coordinated control algorithm for rear-side collision avoidance has been evaluated via simulation using CarSim and MATLAB/Simulink.

• 로봇학회논문지
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• 제12권3호
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• pp.258-262
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• 2017

In this paper, we propose a new collision detection algorithm for human-robot collaboration. We use an IMU sensor located at the tip of the manipulator and the kinematic behavior of the manipulator to detect the unexpected collision between the robotic manipulator and environment. Unlike other method, the developed algorithm uses only the kinematic relationship between the manipulator joint and the end effector. Therefore, the collision estimation signal is not affected by the error of the dynamics model. The proposed collision detection algorithm detects the collision by comparing the estimated acceleration of the end effector derived from the position, velocity and acceleration trajectories of the robot joints with the actual acceleration measured by the sensor. In simulation, we compare the performance of our method with the conventional Residual Observer (ROB). Our method is less sensitive to the load variation because of the independency on the dynamic modeling of the manipulator.

• 한국항공우주학회지
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• 제36권10호
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• pp.996-1002
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• 2008

본 논문에서는 3차원 일대일 충돌 감지, 충돌 회피 및 경로점 유도를 위한 알고리듬에 대해 다룬다. 항공기는 질점 모델로 가정하였다. 충돌 감지는 최근접점까지 남은 시간과 그 때의 거리를 기준 값과 비교하여 수행하였다. 충돌 회피는 최적 제어 이론을 이용하여 최종 시간에서의 상대 거리를 최대화하는 가속도 입력을 계산하여 수행하였다. 경로점 유도는 잘 알려진 비례항법유도를 적용하였다. 제안된 알고리듬의 성능은 두 개의 시나리오를 통하여 검증하였다.

• 제어로봇시스템학회논문지
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• 제14권7호
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• pp.635-641
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• 2008

In this paper, we used a laser range finder (LRF) to detect both the static and dynamic obstacles for the safe navigation of a mobile robot. LRF sensor measurements containing the information of obstacle's geometry are first processed to extract the characteristic points of the obstacle in the sensor field of view. Then the dynamic states of the characteristic points are approximated using kinematic model, which are tracked by associating the measurements with Probability Data Association Filter. Finally, the collision avoidance algorithm is developed by using fuzzy decision making algorithm depending on the states of the obstacles tracked by the proposed obstacle tracking algorithm. The performance of the proposed algorithm is evaluated through experiments with the experimental mobile robot.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.849-854
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• 2007

This paper describes design and tuning of a full-range Adaptive Cruise Control (ACC) with collision avoidance. The control scheme is designed to control the vehicle so that it would feel natural to the human driver and passengers during normal safe driving situations and to avoid rear-end collision in vehicle following situations. In this study, driving situations are determined using a non-dimensional warning index and time-to-collision (TTC). A confusion matrix method based on natural driving data sets was used to tune control parameters in the proposed ACC System. An ECU-Brake Hardware-in-the-loop Simulation (HiLS) was developed and used for an evaluation of ACC System. The ECU-Brake HiLS results for alternative driving situation are compared to manual driving data measured on actual traffic way. The ACC/CA control logic implemented in an ECU was tested using the ECU-Brake HiLS in a real vehicle environment.

• 드라이브 ㆍ 컨트롤
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• 제19권3호
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• pp.23-31
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• 2022

Traffic safety issues have recently been seriously magnified, due to child deaths in apartment complexes and parking lots. Accordingly, traffic safety technologies are being developed to recognize dangerous situations on living roads and to provide warning services. In this study, a collision detection algorithm was developed to prevent collision accidents between moving objects, by using object type and location information provided from CCTV monitoring devices. To determine the exact collision between moving objects, an object movement model was developed to predict the range of movement by considering the moving characteristics of the object, and a collision detection algorithm was developed to efficiently analyze the presence and location of the collision. The developed object movement model as well as the collision detection algorithm were simulated, in a virtual space of an actual living road to verify performance and derive supplementary matters.

• 제어로봇시스템학회논문지
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• 제13권7호
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• pp.631-636
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• 2007

An efficient obstacle avoidance algorithm is proposed in this paper to avoid dynamic obstacles using a collision vector while a tele-operated mobile robot is moving. For the verification of the algorithm, an operator watches through a monitor and controls the mobile robot with a force-reflection joystick. The force-reflection joystick transmits a virtual force to the operator through the Inter-net, which is generated by an adaptive impedance algorithm. To keep the mobile robot safe from collisions in an uncertain environment, the adaptive impedance algorithm generates the virtual force which changes the command of the operator by pushing the operator's hand to a direction to avoid the obstacle. In the conventional virtual force algorithm, the avoidance of moving obstacles was not solved since the operator cannot recognize the environment realistically by the limited communication bandwidth and the narrow view-angle of the camera. To achieve the dynamic obstacle avoidance, the adaptive virtual force algorithm is proposed based on the collision vector that is a normal vector from the obstacle to the mobile robot. To verify the effectiveness of the proposed algorithm, mobile robot navigation experiments with multiple moving obstacles have been performed, and the results are demonstrated.