• 한국항공우주학회지
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• 제39권6호
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• pp.535-542
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• 2011

위성항법시스템은 다양한 분야에서 활용되고 있으며 정밀한 위성항법 위치 정보를 이용하여 자율주행차량(AGV: Autonomous Guided Vehicle)에 활용하는 연구가 진행되고 있다. 위성항법을 이용하여 AGV를 제어하는 경우 지상 시설의 설치 없이 위성항법 기반의 위치 정보를 저장하여 주행 경로를 설정하므로 기존 AGV에 비해 주행 경로 설정이 효율적이다. 특히 주행 경로 상에 장애물이 감지된 경우 기존 AGV의 경우 정해진 경로만을 주행하므로 정지해야만 한다. 그러나 위성항법 기반 AGV는 장애물을 피할 수 있는 주행 경로를 설정할 수 있으므로 연속적인 주행이 가능하다. 본 논문에서는 레이저 스캐너와 회피 벡터를 이용한 회피 경로 설정 알고리즘을 이용하여 위성항법 기반 AGV의 충돌 회피 시스템을 구성한 후 그 성능을 분석하였다.

• Journal of Mechanical Science and Technology
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• 제19권6호
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• pp.1290-1303
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• 2005

In this research, a remote control system has been developed and implemented, which combines autonomous obstacle avoidance in real-time with force-reflective tele-operation. A tele-operated mobile robot is controlled by a local two-degrees-of-freedom force-reflective joystick that a human operator holds while he is monitoring the screen. In the system, the force-reflective joystick transforms the relation between a mobile robot and the environment to the operator as a virtual force which is generated in the form of a new collision vector and reflected to the operator. This reflected force makes the tele-operation of a mobile robot safe from collision in an uncertain and obstacle-cluttered remote environment. A mobile robot controlled by a local operator usually takes pictures of remote environments and sends the images back to the operator over the Internet. Because of limitations of communication bandwidth and the narrow view-angles of the camera, the operator cannot observe shadow regions and curved spaces frequently. To overcome this problem, a new form of virtual force is generated along the collision vector according to both distance and approaching velocity between an obstacle and the mobile robot, which is obtained from ultrasonic sensors. This virtual force is transferred back to the two-degrees-of-freedom master joystick over the Internet to enable a human operator to feel the geometrical relation between the mobile robot and the obstacle. It is demonstrated by experiments that this haptic reflection improves the performance of a tele-operated mobile robot significantly.

• Journal of Positioning, Navigation, and Timing
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• 제12권3호
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• pp.289-294
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• 2023

As technologies such as cameras, Laser Imaging, Detection, and Ranging (LiDAR), and Global Navigation Satellite Systems (GNSS) become more sophisticated and common, their use in autonomous driving technologies is being explored in various fields. In the maritime area, technologies related to collision avoidance between ships are being developed to evaluate and avoid the risk of collision between ships by setting various scenarios. However, the position of each vessel used in the process of developing collision avoidance technology between vessels uses data obtained through GNSS, and may include a position error of 10 m or more depending on the situation. In this paper, a study on the dynamic safety navigation range including the positional inaccuracy of the ship is conducted. By combining the concept of the protection level obtained using GNSS raw data with a conventional safe navigation range, a safer navigation range can be calculated for dynamic navigation. The calculated range is verified using data obtained while sailing in an actual sea environment.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권4호
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• pp.223-232
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• 2003

This paper presents a new method driving multiple robots to their goal position without collision. Each robot adjusts its motion based on the information on the goal location, velocity, and position of the robot and the velocity and position of the .other robots. To consider the movement of the robots in a work area, we adopt the concept of avoidability measure. The avoidability measure figures the degree of how easily a robot can avoid other robots considering the following factors: the distance from the robot to the other robots, velocity of the robot and the other robots. To implement the concept in moving robot avoidance, relative distance between the robots is derived. Our method combines the relative distance with an artificial potential field method. The proposed method is simulated for several cases. The results show that the proposed method steers robots to open space anticipating the approach of other robots. In contrast, the usual potential field method sometimes fails preventing collision or causes hasty motion, because it initiates avoidance motion later than the proposed method. The proposed method can be used to move robots in a robot soccer team to their appropriate position without collision as fast as possible.

• 제어로봇시스템학회논문지
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• 제6권7호
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• pp.537-543
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• 2000

mathematical models for a hydraulic brake actuator and a brake control law for vehicle collision warning/collision avoidance (CW/CA) systems will be presented in this paper. The control law have been designed for optimzied safety and comfort. A solenoid-valve-controlled hydraulic brake actuator system for the CW/CA systems has been investigated, A nonlinear computer model and a linear model of the hydraulic brake actuator system have been developed. Both models were found to represent the actual system with good accuracy. Uncertainties in the brake actuator model have been considered in the design of the control law for the roubustness of the controller. The effects of brake control on CW/CA vehicle response has been investigated via simulations. The simulations were performed using the hydraulic brake system model and a complete nonlinear vehicle model. The results indicate that the proposed brake control law can provide the CW/CA vehicles with an opimized compromise between safety and comfort.

• 한국항공우주학회지
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• 제40권6호
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• pp.515-522
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• 2012

항공기 사고 중에서 주요 원인 중 하나인 조종상태 지상충돌(Controlled Flight Into Terrain, CFIT)을 해결하기 위하여 대지 접근 경고 장치(Ground Proximity Warning System, GPWS)를 사용하여 항공기 아랫부분의 지형에 대해서 지형충돌 경고를 출력한다. 이러한 대지 접근 경고 장치도 적시에 경고가 발생하지 않아 많은 문제가 있었다. 본 논문에서는 비행 상태와 지형정보를 이용하여 속도가 빠르고, 고기동을 하는 전투기에 대해서 보다 효율적인 지형/장애물 충돌 회피 경고 알고리듬을 개발하였다. 이 알고리듬에는 조종사의 반응시간을 포함하여 항공기의 지연시간을 고려하였고, 일련의 검증을 통해 실제 탑재 가능한 알고리듬을 제시하였다.

• 한국멀티미디어학회논문지
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• 제15권10호
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• pp.1236-1246
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• 2012

자율 주행 로봇은 스스로 운행할 능력이 있으므로 사람이 접근하기 어려운 위험한 장소 또는 좁은 장소 등에 갈 수 있고 센서를 이용하여 사람이나 프로그램이 지시하는 명령을 수행할 수도 있다. 그리고 센서를 이용해 얻은 데이터를 다시 전송해 줄 수 있다. 지시된 장소까지 주행하기 위해 장애물이나 다른 이웃 로봇에 충돌하지 않고 원하는 목적지까지 진행 하여야 한다. 본 연구에서는 로봇의 자율 주행을 위한 충돌 회피 방법을 설계하고 구현하였다. 충돌회피를 위해 더듬이, IR 및 초음파 센서를 사용하여 근거리 장애물과 원거리 장애물을 감지하여 회피 할 수 있게 하였다. 또한 임무 수행 후 데이터를 전송하기 위해 유, 무선 통신을 이용하였다.

• 자동차안전학회지
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• 제14권4호
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• pp.84-90
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• 2022

With the popularization of autonomous driving technology, safety has emerged as a more important criterion. However, there are no assessment protocol or methods for AES (Autonomous Emergency Steering). So, this study proposes AES assessment protocol and scenario corresponding to collision avoidance Car-to-Car scenario of Euro NCAP in order to prepare for obstacles that appear after the emergency steering of LV (Leading Vehicle) avoiding obstacles in front of. Autoware-based autonomous driving stack is developed to test and simulate scenario in CARLA. Using developed stack, it is confirmed that obstacle avoidance is successfully performed in CARLA, and the AES performance of VUT (Vehicle Under Test) is evaluated by applying the proposed assessment protocol and scenario.

• 로봇학회논문지
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• 제17권3호
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• pp.359-364
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• 2022

This study presents a nonlinear model predictive control (NMPC)-based obstacle avoidance and whole-body motion planning method for the mobile manipulators. For the whole-body motion control, the mobile manipulator with an omnidirectional mobile base was modeled as a nine degrees-of-freedom (DoFs) serial open chain with the PPR (base) plus 6R (arm) joints, and a swept sphere volume (SSV) was applied to define a convex hull for collision avoidance. The proposed receding horizon control scheme can generate a trajectory to track the end-effector pose while avoiding the self-collision and obstacle in the task space. The proposed method could be calculated using an interior-point (IP) method solver with 100[ms] sampling time and ten samples of horizon size, and the validation of the method was conducted in the environment of Pybullet simulation.