• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2743-2746
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• 2003

In this paper, we propose a new weaving trajectory algorithm for the arc welding of a articulated manipulator. The algorithm uses the theory of Bezier spline. We make a comparison between the conventional algorithms using Catmull-Rom curve and the new algorithms using Bezier spline. The proposed algorithm has been evaluated based on the MATLAB environment in order to illustrate its good performance. The algorithm has been implemented on to the industrial manipulator of DR6 so as to show its real possibility. Through simulations and real implementations, the proposed algorithm can result in high-speed and flexible weaving trajectory planning and can reduce the processing time because it needs one-half calculation compared to the conventional algorithm using Catmull-Rom curve.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.10
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• pp.50-58
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• 1993

The problem of trajectory planning in two redundant robot systems is considered. The trajectory of each robot for the cooperative task is generated so that the robots assume their optimal configurations while following a given desired task. The cooperative task compatibility in and the weighted sum of manipulabilities are proposed and investigated as quality measures. The cooperative task compatibility includes the velocity and force transmission charateristics to the task requirements and so it measures the compatibilities of robot postures with respect to a given task. The weighted sum of manipuabilities of robot postures with respect to a given task. The weighted sum of manipulabilities is also considered as a quality measure since it is helpful to avoid singularities. The usefulness of the cooperative task compatibility and the weighted sum of manipulabilities are shown by computer simulation studies.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.621-626
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• 1989

An efficient algorithm for planning near-optimum trajectory of manipulators is proposed. The algorithm is divided into two stages. The first one is the optimization of time trajectory with given spatial path. And the second one is the optimization of the spatial path itself. To consider the second problem, the manipulator dynamics is represented using the path parameter "s", then a differential equation corresponding to the dynamics is solved as two point boundary value problem. In this procedure, the gradient method is used to calculate improved input torques.t torques.

• 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.

• 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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• 1992.10b
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• pp.599-606
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• 1992

A manipulator system that needs significantly large workspace volume and high payload capacity has greater link flexibility than typical industrial robots and teleoperators. If link flexibility is significant, position control of the manipulator's end-effector exhibits the nonminimum phase, noncollocated, and flexible structure system control problems. This paper addresses inverse dynamic trajectory planning issues of a flexible manipulator. The inverse dynamic equation of a flexible manipulator was solved in the time domain. By dividing the inverse system equation into the causal part and the anticausal part, the inverse dynamic method calculates the feedforward torque and the trajectories of all state variables that do not excite structural vibrations for a given end-point trajectory. Through simulation and experiment with a single-Unk flexible manipulator, the effectiveness of the inverse dynamic method has been demonstrated.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.3
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• pp.143-148
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• 2001

A lot of robot trajectory tracking methods are proposed to enhance the tracking error, but irregular tracking errors are always accompanied and very hard to reduce it. Up to now, these irregular tracking errors are reduced by introducing more complicated control algorithms. But, it is intuitively obvious to reduce only the big errors selectively in the irregular ones for the better performance instead of using more complicated control algorithms. By the characteristics of the robot, big tracking errors of the end-effector are generated mostly due to the fast moving of joint. So, in this paper, we introduce a new method which reduce the big tracking errors by clippings the joint velocity with the constraint of given path. Using this method, desired trajectory tracking is obtained within the far reduced error bound. Also, this method is successfully applied to generate the path-constrained error reducing trajectories for 2-axis SCARA type robot.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2002.06a
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• pp.161-165
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• 2002

This paper describe a trajectory generation method for a soccer robot using cubic Bezier curve. It is proposed that the method to determine the location of control points. The control points are determined by the distance and the velocity parameters of start and target positions. Simulation results show its traceability of the trajectory of mobile robot.

• Advances in aircraft and spacecraft science
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• v.7 no.1
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• pp.53-78
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• 2020

Automatic trajectory planning is an important task that will have to be performed by truly autonomous vehicles. The main method proposed, for unmanned airplanes to do this, consists in concatenating elementary segments of trajectories such as rectilinear, circular and helical segments. It is argued here that because these cannot be expected to all be flyable at a same constant speed, it is necessary to consider segments on which the airplane accelerates or decelerates. In order to preserve the planning advantages that result from having the speed constant, it is proposed to do all speed changes at maximum deceleration or acceleration, so that they are as brief as possible. The constraints on the load factor, the lift and the power required for the motion are derived. The equation of motion for such accelerated motions is solved numerically. New results are obtained concerning the value of the angle and the speed for which the longest distance and the longest duration glides happen, and then for which the steepest, the fastest and the most fuel economical climbs happen. The values obtained differ from those found in most airplane dynamics textbooks. Example of tables are produced that show how general speed changes can be effected efficiently; showing the time required for the changes, the horizontal distance traveled and the amount of fuel required. The results obtained apply to all internal combustion engine-propeller driven airplanes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.1
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• pp.74-80
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• 2006

This paper addresses the trajectory optimization of Unmanned Aerial Vehicles(UAVs) under multiple ground threats like enemy's anti-air radar sites. The power of radar signal reflected by the vehicle and the flight time are considered in the performance cost to be minimized. The bank angle is regarded as control input for a 1st-order lag vehicle, and input parameter optimization method based on Sequential Quadratic Programming (SQP) is used for trajectory optimization. The proposed path planning method provides more practical trajectories with enhanced survivability than those of Voronoi diagram method.