• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.12
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• pp.1992-2007
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• 1997

A new algorithm for planning a collision-free path is developed based on linear prametric curve. In this paper robot is assumed to a point, and two linear parametric curve is used to construct a path connecting start and goal point, in which single intermediate connection point between start and goal point is considered. The intermediate connection point is set in polar coordinate(${\theta}{\delta}$) , and the interference between path and obstacle is mapped into CPS(connection point space), which is defined a CWS GM(circular work space geometry mapping). GM of all obstacles in workspace creates overlapping images of obstacle in CPS(Connection Point Space). The GM for all obstacles produces overlapping images of obstacle in CPS. The empty area of CPS that is not occupied by obstacle images represents collision-free paths in Euclidian Space. A GM based on connection point in elliptic coordinate(${\theta}{\delta}$) is also developed in that the total length of path is depend only on the variable .delta.. Hence in EWS GM(elliptic work space geometry mapping), increasing .delta. and finding the value of .delta. for collision-free path, the shortest path can be searched without carring out whole GM. The GM of obstacles expersses all possible collision-free path as empty spaces in CPS. If there is no empty space available in CPS, it indicates that path planning is not possible with given number of connection points, i.e. path planning is failed, and it is necessary to increase the number of connection point. A general case collision-free path planning is possible by appling GM to configuration space obstacles. Simulation of GM of obstacles in Euclidian space is carried out to measure performance of algorithm and the resulting obstacle images are reported.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.11
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• pp.970-975
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• 2002

We suggests an effective method to construct time-varying C-obstacles in the 3-dimensional configuration space (C-space) using free arc. The concept of free arc was defined mathematically and the procedure to find free arc in the case off-dimensional C-space was derived in [1]. We showed that time-varying C-obstacles can be constructed efficiently using this concept, and presented simulation results for two SCARA robot manipulators to verify the efficacy of the proposed approach. In this paper, extensions of this approach to the 3-dimensional C-space is introduced since nearly all industrial manipulators are reasonably treated ill the too or three dimensional C-space f3r collision avoidance problem The free arc concept is summarized briefly and the method to find lice arc in the 3-dimensional f-space is explained. To show that this approach enables us to solve a practical collision avoidance problem simulation results f3r two PUMA robot manipulators are presented.

• The Journal of Korea Robotics Society
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• v.2 no.3
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• pp.234-241
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• 2007

Effective tools which can alleviate the complexity and computational load problem in collision-free motion planning for multi-agent system have steadily been demanded in robotics field. To reduce the complexity, the extended collision map (ECM) which adopts decoupled approach and prioritization is already proposed. In ECM, the collision regions which represent the potential collision of robots are calculated using the computational power; the complexity problem is not resolved completely. In this paper, we propose a mathematical analysis of the extended collision map; as a result, we formulate the collision region as an equation with 5-8 variables. For mathematical analysis, we introduce realistic assumptions as follows; the path of each robot can be approximated to a straight line or an arc and every robot moves with uniform velocity or constant acceleration near the intersection between paths. Our result reduces the computational complexity in comparison with the previous result without losing optimality, because we use simple but exact equations of the collision regions. This result can be widely applicable to coordinated multi-agent motion planning.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.2
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• pp.63-70
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• 2012

The collision-free flight planning method based on the extended collision map is proposed for cooperation of multiple unmanned aerial vehicles (UAVs) in a common 3-dimensional workspace. First, a UAV is modeled as a sphere, taking its 3-D motions such as rolling into consideration. We assume that after entering the common workspace, the UAVs move along their straight paths until they depart from the workspace, and that the priorities of the UAVs are determined in advance. According to the assumptions, the collision detection problem between two spheres in $R^3$ can be reduced into the collision detection problem between a circle and a line in $R^2$. For convenience' sake and safety, the collision regions are approximated by collision boxes. Using the collision boxes, the entrance times of the UAVs are scheduled for collision avoidance among the UAVs. By this way, all UAVs can move in the common workspace without collisions with one another. For verifying the effectiveness of the proposed flight planning method, the simulation with 12 UAVs is carried out.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.6
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• pp.35-42
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• 2002

Verification of tool collision Is an important issue in die and mold machining. In this paper three functions of verification for 3-axis milling machining are schematically explained. Operators of geometric models are explained at first, which will be used in the functions of verification. The first verification function is getting a collision-free region when a tool assembly and a part surface model are given. The second function estimates the shortest length of cutter shank with that the tool cuts all of a region without collision The last one is cutting simulation considering all parts of tool assembly as well as cutter blade. Proposed approaches can be easily implemented by using several basic operators of geometric model. An example to calculate collision-free region is presented also.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.649-652
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• 1989

In this paper we outline an approach for the collision-free trajectory planning of two robot arms which are modeled as connected line segments. A new approach to determine the collision between two robot arms and the boundary of the collision region in the coordination space is proposed. The coordination curve may then be chosen to avoid the collision region. For minimum time trajectory, time is assigned to this curve by dynamic time scaling under constraints such as maximum torque or maximum angular velocity of each actuator. A comparison of the proposed method and the graphical method of determining the collision region is also included. Finally, as an example, some simulation results for two SCARA type robots are presented.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.629-634
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• 1995

The purpose of this paper is to develop a method of Collision-Free Path Planning (CFPP) for an articulated robot. First, the configuration of the robot is formed by a set of robot joint angles derived fromm robot inverse kinematics. The joint space that is made of the joint angle set, forms a Configuration space (Cspace). Obstacles in the robot workcell are also transformed and mapped into the Cspace, which makes Cobstacles in the Cspace. (The Cobstacles represented in the Cspace is actually the configurations of the robot causing collision.) Secondly, a connected graph, a kind of roadmap, is constructed from the free configurations in the 3 dimensional Cspace, where the configurations are randomly sampled form the free Cspace. Thirdly, robot paths are optimally in order to minimize of the sum of joint angle movements. A path searching algorithm based on A is employed in determining the paths. Finally, the whole procedures for the CFPP method are illustrated with a 3 axis articulated robot. The main characteristics of the method are; 1) it deals with CFPP for an articulated robot in a 3-dimensional workcell, 2) it guarantees finding a collision free path, if such a path exists, 3) it provides distance optimization in terms of joint angle movements. The whole procedures are implemented by C on an IBM compatible 486 PC. GL (Graphic Library) on an IRIS CAD workstation is utilized to produce fine graphic outputs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.2C
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• pp.161-166
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• 2008

In the parallel-architecture turbo codes, the constituent interleaver must avoid memory collision. This paper proposes a collision-free interleaver structure composed of a Latin square matrix and pre-designed interleavers. Our proposed interleavers can be easily optimized for various information block sizes and for various degrees of parallelism. Their performances were evaluated by computer simulation.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.6
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• pp.57-65
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• 1994

A collision-free path planning algorithm between an articulated robot and polyhedral obstacles using configuration space is presented. In configuration space, a robot is treated as a point and obstacles are treated as grown forbidden regions. Hence path planning problem is transformed into moving a point from start position to goal position without entering forbidden regions. For mapping to 3D joint space, slice projection method is used for first revolute joint and inverse kinematics is used for second and third revolute joint considering kinematic characteristics of industrial robot. Also, three projected 2D joint spaces are used in search of collision-free path. A proper example is provided to illustrate the proposed algorithm.

• Journal of Advanced Navigation Technology
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• v.19 no.5
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• pp.379-388
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• 2015

In the end of 1990's, future free flight technology had been developed and tested in America and government established the plan for free flight until 2017. Aircraft separation assurance must be secured essentially to avoid collision between aircrafts before Free Flight comes true. Now, Civil aircraft has rules about avoidance activity with traffic collision avoidance system (TCAS) but it can't apply to light aircraft. So there is a need about alternative method to apply light-aircraft because it has space and price problem to use TCAS. In this paper, TCAS algorithm has been modified and verified by simulating with LABVIEW program under ADS-B condition to get miniaturization and weight lighting cheaply. By simulating, collision alert algorithm is analyzed and verified with collision situation proposed by ICAO, and 100% checked for performing the alert announciation on all cases by TCAS standards.