• 한국항해학회지
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• 제15권2호
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• pp.13-38
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• 1991

This paper intends to develop a Prototype Expert Collision Avoidance System by introducing expert system techniques into the decision block of anti-collision loop. The problem domain of this study is characterized and specified by combining the concepts of anti-collision loop and knowledge -based system for collision avoidance. Domain in knowledge which may originates from the appropriate sources such as the International Regulations for Preventing Collision at Sea 1972, Marine Traffic Laws, and many texts on the subject of anticollision navigation and good seamanship is acquired and formalized into the knowledge-base system using production rule. Finally, a Prototype Expert Collision Avoidance System is built by using the CLIPS, developed by AIS NASA written in and fully integrated with the C language, and some test-and-run results of the system are demonstrated and examined. The author considers the proposed system which is named PECAS to be meaningful as a test bed for a further refined Expert Collision Avoidance System on board the Automated Ship.

• Journal of Mechanical Science and Technology
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• 제19권11호
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• pp.1998-2006
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• 2005

The lane departure avoidance systems have been considered promising to assist human drivers in AVCS (Advanced Vehicle Control System). In this paper, a lane departure monitoring and control system is developed and evaluated in the hardware-in-the-loop simulations. This system consists of lane sensing, lane departure monitoring and active steering control subsystems. The road image is obtained based on a vision sensor and the lane parameters are estimated using image processing and Kalman Filter technique. The active steering controller for avoiding the lane departure is designed based on the lane departure metric. The proposed lane departure avoidance system is realized in a steering HILS (hardware-in-the-loop simulation) tool and its performance is evaluated with a driver in the loop.

• 한국자동차공학회논문집
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• 제11권6호
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• pp.222-228
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• 2003

Lane departure avoidance system is one of the key technologies for the future active-safety passenger cars. The lane departure avoidance system is composed of two subsystems; lane sensing algorithm and active-steering controller. In this paper, the road image is obtained by vision sensor and the lane parameters are estimated using image processing and Kalman Filter technique. The active-steering controller is designed to prevent the lane departure. The developed active-steering controller can be realized by steer-by-wire actuator. The lane-sensing algorithm and active-steering controller are implemented into the steering HILS(Hardware-In-the-Loop Simulation) and their performance is evaluated with a human driver in the loop.

• 한국항공운항학회지
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• 제25권4호
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• pp.83-90
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• 2017

Unmanned Aerial Vehicles(UAVs) require collision avoidance capabilities equivalent to the capabilities of manned aircraft to enter the airspace of manned aircraft. In the case of Visual Flight Rules of manned aircraft, collision avoidance is performed by 'See-and-Avoid' of pilots. To obtain those capabilities of UAVs named as 'Sense-and-Avoid', sensor-system-based intruder tracking and collision avoidance methods are required. In this study, a multi-sensor-based tracking, data fusion, and collision avoidance algorithm is designed by using a model-based design tool MATLAB/SIMULINK, and validations of the designed model and code using numerical simulations and processor-in-the-loop simulations are performed.

• 한국자동차공학회논문집
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• 제7권5호
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• pp.240-248
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• 1999

This paper presents a lane-change collision avoidance control algorithm for autonomous vehicles that will be used in AHS(Automated Highway System). In the proposed control algorithm, nominal control inputs are generated by solving the inverse vehicle dynamic equations of motion for a lane-change maneuver. In addition, a corrective steering input from preview as well as DYC (Direct Yaw Moment Control) may be included to reduce unpredictable errors and to insure yaw directional stability, respectively. The performance of the algorithm is evaluated with an ABS HILS system which consist of 17 DOF vehicle model and real ABS hardware parts. The HILS simulation results show that the proposed algorithm may be used for emergency lane-change maneuvers for autonomous vehicles.

• 한국멀티미디어학회논문지
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• 제23권8호
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• pp.1088-1098
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• 2020

This paper proposes an obstacle avoidance method using a depth polar grid. Depth information is a crucial factor for determining the safe path for collision-free navigation of unmanned aerial vehicles (UAVs) as it can perceive the distance to the obstacles effectively. However, the existing depth-camera-based approaches for obstacle avoidance require computational y expensive path planning algorithms. We propose a simple navigation method using the polar-grid of the depth information obtained from the camera with narrow field-of-view(FOV). The effectiveness of the approach was validated by a series of experiments using software-in-the-loop simulation in a realistic outdoor environment. The experimental results show that the proposed approach successfully avoids obstacles using a single depth camera with limited FOV.

• 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.

• 한국항공우주학회지
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• 제42권9호
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• pp.752-761
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• 2014

뛰어난 기동성으로 인한 최근 쿼드로터에 대한 관심의 증대는 다양한 형태의 멀티로터 비행체의 개발 및 상용화를 이끌었으며, 레져용으로 사용자들이 쉽게 사용할 수 있는 다양한 쿼드로터 제품들이 등장하고 있다. 이 중에서 최근 Parrot사에서 제작한 AR.Drone은 사용자를 위한 내부 안정화 루프를 탑재하고 있기 때문에 초보자들도 쉽게 제어할 수 있는 장점이 있다. 이러한 AR.Drone의 시스템을 이용하면 다양한 형태의 다수 무인기 시스템을 쉽게 구축할 수 있다. 이러한 특성을 바탕으로 한국항공우주연구원에서는 다수의 AR.Drone을 이용한 실내 군집비행 연구를 진행 중에 있다. 이러한 다수의 무인비행체를 이용한 실내 군집비행을 위해서는 개개의 비행체에 대한 위치제어 및 서로간의 충돌을 방지하기 위한 알고리즘이 필요하다. 이를 위해서 본 논문에서는 다수의 실내 무인기의 원활한 기동을 위해 개발한 충돌회피 기동 제어기를 소개하고자 한다.

• 정보과학회 논문지
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• 제43권11호
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• pp.1233-1244
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• 2016

저전력, 저품질의 네트워크 환경인 LLNs(Low power and Lossy Networks) IoT 네크워크 환경에서는 IETF에서 제안한 IPv6 라우팅 프로토콜인 RPL이 대표적으로 사용된다. RPL은 루프가 존재하지 않는 방향성 비순환 그래프(Directed Acyclic Graph)를 생성하는 것을 목표로 하며, 이를 위해 loop avoidance, loop detection 메커니즘과 문제 발생 시 복구를 위한 DIO Poisoning 메커니즘을 정의하고 있다. 하지만, 기존의 DIO Poisoning은 루프 발생 노드에서 일어난 poisoning이 해당 노드의 서브트리로 전파되어 복구 시간과 컨트롤 메시지가 증가하는 문제점을 가지고 있다. 본 논문에서는 RPL 기반 IoT 무선 네트워크에서 루프 복구 과정 시 서브 트리의 라우팅 오버헤드가 추가로 발생할 수 있는 현상을 보완한 효율적인 경로 복구 기법을 제안한다. 개선된 RPL 루프 복구 과정에서는 기존 선호 부모로 선택될 수 없던 경로를 활용하여 빠르게 복구함으로써 새로운 경로설정을 위한 컨트롤 패킷 트래픽과 경로 복구 시간을 줄인다. 시뮬레이션을 사용하여 제안한 프로토콜이 기존 프로토콜에 비해 복구 시간 단축과 컨트롤 패킷의 감소를 통한 복구 성능을 향상시킬 수 있음을 알 수 있었다.

• 로봇학회논문지
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• 제13권2호
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• pp.129-141
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• 2018

This paper proposes a unified framework that overcomes four motion constraints including joint limit, kinematic singularity, algorithmic singularity and obstacles. The proposed framework is based on our previous works which can insert or remove tasks continuously using activation parameters and be applied to avoid joint limit and singularity. Additionally, we develop a method for avoiding obstacles and combine it into the framework to consider four motion constraints simultaneously. The performance of the proposed framework was demonstrated by simulation tests with considering four motion constraints. Results of the simulations verified the framework's effectiveness near joint limit, kinematic singularity, algorithmic singularity and obstacles. We also analyzed sensitivity of our algorithm near singularity when using closed loop inverse kinematics depending on magnitude of gain matrix.