• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.5
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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.

• ETRI Journal
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• v.45 no.5
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• pp.746-757
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• 2023

This study presents a novel safe landing algorithm for urban drone deliveries. The rapid advancement of drone technology has given rise to various delivery services for everyday necessities and emergency relief efforts. However, the reliability of drone delivery technology is still insufficient for application in urban environments. The proposed approach uses the "landing angle control" method to allow the drone to land vertically and a rapidly exploring random tree-based collision avoidance algorithm to generate safe and efficient vertical landing paths for drones while avoiding common urban obstacles like trees, street lights, utility poles, and wires; these methods allow for precise and reliable urban drone delivery. We verified the approach within a Gazebo simulation operated through ROS using a six-degree-of-freedom drone model and sensors with similar specifications to actual models. The performance of the algorithms was tested in various scenarios by comparing it with that of stateof-the-art 3D path planning algorithms.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.18 no.3
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• pp.27-33
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• 2010

The goal for the CD&R system is to predict that a conflict is going to occur in the future, communicate the detected conflict to a human operator, and, in some cases, assist in the resolution of the conflict situation. To provide insight into different methods of conflict detection and resolution, a literature review of previous research models and current developmental and operational systems was performed. This paper focuses only on the specific attributes of each model, not on the depth to which a model has been analyzed, validated, or accepted. Thus, care should be taken to remember that a model that seems to be simple according to our categorization scheme may be significantly more viable than an apparently sophisticated model.

• Proceedings of the Korean Society of Computer Information Conference
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• 2012.01a
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• pp.49-50
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• 2012

본 논문에서는 다수의 소형 무인 항공기(UAV) 그룹이 이동 중 장애물을 만났을 때 장애물과의 충돌을 방지하는 효율적인 장애물 회피 정책을 제안한다. 이 정책은 무선 에드혹(moblie ad hoc) 네트워크를 기반으로 단순히 UAV 간의 충돌 회피 뿐만이 아니라 UAV 그룹이 이동하는 도중 장애물을 발견 하였을 경우 장애물을 효율적으로 회피하는 방법과 연결성이 손실되는 경우에 대처하는 방안도 고려하였다. 제안하는 정책은 UAV가 장애물을 포착 하였을 때 현재 이동 속도를 유지한 채 장애물을 기준으로 UAV 그룹을 2개의 그룹으로 분리하여 장애물을 회피 한 후 일정한 지점에서 모여 다시 각 UAV간의 연결성을 유지한 채 목표물을 향해 이동하는 정책을 제안한다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.5
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• pp.1495-1502
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• 1991

본 연구에서는 동일 작업 공간내에서 두대의 로봇이 각각의 토크의 제한 조건 과 충돌 회피 조건을 만족하면서 근사 최소 시간에 지정된 경로를 주행하기 위한 궤적 계획법을 제안하고자 한다. 이때, 동작 우선도에 의하여 한 대의 로봇은 주 로봇, 다른 한 대의 로봇은 종 로봇으로 지정되는데 주 로봇은 입력 토크의 제한조건을 만족 하며 주어진 경로를 최소 시간에 움직이도록 궤적 계획을 하였으며, 종 로봇은 주 로 봇과의 충돌을 피하고 입력 토크의 제한 조건을 만족하며 주어진 경로를 근사 최소 시 간에 움직이도록 하였다.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1609-1614
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• 2003

This paper presents a new method driving multiple robots to their goal position without collision. To consider the movement of the robots in a work area, we adopt the concept of avoidability measure. To implement the concept in collision avoidance of multiple robots, relative distance between the robots is proposed. The relative distance is a virtual distance between robots indicating the threat of collision between the robots. Based on the relative distance, the method calculates repulsive force against a robot from the other robots. Also, attractive force toward the goal position is calculated in terms of the relative distance. 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. The proposed method works as a local collision-free motion coordination method in conjunction with higher level of task planning and path planning method for multiple robots to do a collaborative job.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.896-899
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• 1996

A new algorithm for planning a collision free path is developed based on linear parametric curve. A collision-free path is viewed as a connected space curve in which the path consists of two straight curve connecting start to target point. A single intermediate connection point is considered in this paper and is used to manipulate the shape of path by organizing the control point in polar coordinate (.theta.,.rho.). The algorithm checks interference with obstacles, defined as GM (Geometry Mapping), and maps obstacles in Euclidean Space into images in CPS (Connection Point Space). The GM for all obstacles produces overlapping images of obstacle in CPS. The clear area of CPS that is not occupied by obstacle images represents collision-free paths in Euclidean Space. Any points from the clear area of CPS is a candidate for a collision-free path. A simulation of GM for number of cases are carried out and results are presented including mapped images of GM and performances of algorithm.

• Journal of Mechanical Science and Technology
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• v.19 no.2
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• pp.505-519
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• 2005

In this paper, we develop an anti-sway control in proposed techniques for an ATC system. The developed algorithm is to build the optimal path of container motion and to calculate an anti-collision path for collision avoidance in its movement to the finial coordinate. Moreover, in order to show the effectiveness in this research, we compared NNP PID controller to be tuning parameters of controller using NN with 2 DOF PID controller. The simulation and experimental results show that the proposed control scheme guarantees performances, trolley position, sway angle and settling time in NNP PID controller than other controller. As the results in this paper, the application of NNP PID controller is analyzed to have robustness about disturbance which is wind of fixed pattern in the yard. Accordingly, the proposed algorithm in this study can be readily used for industrial applications.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.2
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• pp.141-147
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• 2008

In this paper, we present one approach to achieve safe navigation in indoor dynamic environment. So far, there have been various useful collision avoidance algorithms and path planning schemes. However, those algorithms have a fundamental limitation that the robot can avoid only "visible" obstacles. In real environment, it is not possible to detect all the dynamic obstacles around the robot. There exist a lot of "occluded" regions due to the limitation of field of view. In order to avoid possible collisions, it is desirable to consider visibility information. Then, a robot can reduce the speed or modify a path. This paper proposes a safe navigation scheme to reduce the risk of collision due to unexpected dynamic obstacles. The robot's motion is controlled according to a hybrid control scheme. The possibility of collision is dually reflected to a path planning and a speed control. The proposed scheme clearly indicates the structural procedure on how to model and to exploit the risk of navigation. The proposed scheme is experimentally tested in a real office building. The presented result shows that the robot moves along the safe path to obtain sufficient field of view, while appropriate speed control is carried out.

• Journal of Navigation and Port Research
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• v.27 no.4
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• pp.351-357
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• 2003

Evaluating the risk of collision quantitatively plays a key role in developing the expert system of navigation and collision avoidance. This study analysed theoretically and thoroughly how to determine the gradient coefficients as described in the new evaluation of collision risk using sech function, and suggested the appropriate values as applicable.