• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.59-64
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• 1989

In this paper, the launch trajectory of the Japan scientific satellite M-3H-3 from launch to orbit injection is investigated. For the terminal conditions at a guidance target point, a guidance and control system is used. An open-loop and a closed-loop guidance schemes are used simultaneously. For the closed-loop guidance scheme, the velocity polynomial algorithm represented by the velocity difference between the target point and present velocity is used. A PD control system is used for activating gimbal type engines. The simulation result shows that all the terminal position and velocity conditions are satisfied and the trajectory for the M-3H-3 scientific satellite is reasonable.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 B
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• pp.826-829
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• 1995

In this paper, the problem of minimum-time trajectory planning of a robot manipulator with an arbitrary path is dealt. As for a straight path, the trajectory planning can be done without difficulty since the path is easily parameterized by its length. However, this is not the case for a non-straight path. In this paper, by noting that the others' joint angles and velocities are determined if one joint's angle and velocity are known, we reduce the problem of trajectory planning on a non-straight path to one in the 2-dimensional space of one joint's angle and velocity. Then, by applying the dynamic programming, we achieve the minimum-time trajectory planning. A simulation is done for verifying this.

• 제어로봇시스템학회논문지
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• 제12권6호
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• pp.561-567
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• 2006

This paper deals with a fuzzy controller using IA(Immune Algorithm) for Trajectory Tracking of 2-DOF WMR(Wheeled Mobile Robot). The global inputs to the WMR are reference position and reference velocity, which are time variables. The global output of WMR is a current position. The tracking controller makes position error to be converged 0. In order to reduce position error, a compensation velocities on the track of trajectory is necessary. Therefore, a FIAC(Fuzzy-IA controller) is proposed to give velocity compensation in this system. Input variables of fuzzy part are position errors in every sampling time. The output values of fuzzy part are compensation velocities. IA are implemented to adjust the scaling factor of fuzzy part. The computer simulation is performed to get the result of trajectory tracking and to prove efficiency of proposed controller.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1402-1407
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• 2004

Moving a fragile object from an initial point to a goal location in minimum time without damage is pursued in this paper. In order to achieve the goal, first of all, the range of maximum acceleration and velocity are specified, which the manipulator can generate dynamically on the path that is planned a priori considering the geometrical constraints. Later, considering the impulsive force constraint of the object, the range of maximum acceleration and velocity are going to be obtained to keep the object safe while the manipulator is carrying it along the curved path. Finally, a time-optimal trajectory is planned within the maximum allowable range of the acceleration and velocity. This time optimal trajectory planning can be applied for real applications and is suitable for not only a continuous path but also a discrete path.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 D
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• pp.2473-2475
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• 2001

In trajectory tracking methods, the error values of current position and velocity are compensated to follow the given reference path and velocity. The path tracking for a wheeled mobile robot is treated in this paper. It is very difficult to implement stable trajectory tracking algorithms because mobile robots have kinematically non-holonomic constraints. For solving this problem, a velocity controller is presented in this paper. This velocity controller is designed by a PID controller which could be easily employed. In this case, velocity errors caused by system uncertainties or internal and external disturbances could exist. A neural network is used for compensating the velocity errors. Input variables of this neural network compensator are defined by differences between the velocities of the posture controller and the real velocities of the mobile robot. Simulation results show the effectiveness of the proposed controller.

• 전자공학회논문지B
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• 제29B권11호
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• pp.36-45
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• 1992

A numerical trajectory planning method for path-constrained trajectory planning is proposed which ensures collision-free and time-optimal motions for two robotic manipulators with limited actuator torques and velocities. For each robot, physical constraints of the robots such as limited torques or limited rotational velocities of the actuators are converted to the constraints on velocity and acceleration along the path, which is described by a scalar variable denoting the traveled distance from starting point. Collision region is determined on the coordination space according to the kinematic structures and the geometry of the paths of the robots. An Extended Coordination Space is then constructed` an element of the space determines the postures and the velocities of the robots, and all the constraints described before are transformed to some constraints on the behaviour of the coordination-velocity curves in the space. A dynamic programming technique is them provided with on the discretized Extended Coordination Space to derive a collision-free and time-optimal trajectory pair. Numerical example is included.

• Advances in aircraft and spacecraft science
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• 제5권5호
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• pp.551-579
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• 2018

This work is concerned with the motion of propeller driven airplanes, flying at constant velocity on ascending or descending rectilinear trajectories. Its purpose is to provide important features of rectilinear flights that are required for airplane trajectory planning but that cannot be found already published. It presents a method for calculating the amount of fuel used, the restrictions on the trajectory parameters, as inclination and speed, which result from the load factor, the lift coefficient, the positivity and upper boundedness of the power available. It presents a complete discussion of both ascending and descending flights, including gliding. Some original remarks are made about the parameters of gliding. It shows how to construct tables of parameters allowing to identify rapidly flyable trajectories. Sample calculations are shown for the Cessna 182 and a Silver Fox like unmanned aerial vehicle.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 B
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• pp.843-845
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• 1995

There are a variety of trajectory and control algorithms available for robot trajectory tracking. Before using the enhanced trajectory and control algorithms to reduce the tracking error, we introduce the new method which reduces the tracking error by clipping the joint velocity. A lot of robot trajectory tracking methods are proposed to enhance the robot tracking, but irregular tracking errors are always accompanied. Up to now, these irregular tracking errors are gradually but uniformly reduced by introducing more complicated control algorithms. It is intuitively obvious to reduce only the big errors selectively in the irregular ones for the better performance. By heuristic method, big tracking errors in these irregular ones are assumed mostly due to the fast moving of joint with respect to the same tracking and control method. 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.

• 한국지능시스템학회논문지
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• 제24권1호
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• pp.52-57
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• 2014

본 논문은 두 바퀴 이동로봇의 주행에 있어서 주어진 경로를 물리적 제한을 만족하면서 주행하는 관절 공간 궤적 생성방법을 실시간 운영체제를 이용하여 구현함으로써 실시간 제어 방법에 대하여 연구하였다. 경로계획에서 이동로봇의 방향을 고려하기 위하여 베지어곡선을 이용하였으며, 컨볼루션 연산자를 이용하여 로봇의 두 바퀴의 속도의 제한을 만족시켰다. 관절 공간의 궤적 생성과 생성된 궤적에 대한 속도명령, 그리고 엔코더 값 감시 등 실시간 태스크를 주기적 태스크로 구현하였으며 동기화를 위하여 실시간 메커니즘인 이벤트 플래그를 이용하여 구현하였다. 실제 로봇에 실시간 태스크를 구현하여 속도명령의 실시간성과 이에 따른 이동로봇의 주행실험 결과를 이용하여 궤적 추종 성능을 비실시간 시스템과 분석하였다. 결과를 통하여 실시간 성을 요구하는 제어시스템에서 실시간 다중 태스크 시스템의 유용성을 검증하였다.

• 한국항공우주학회지
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• 제32권6호
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• pp.72-80
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• 2004

본 논문에서는 추력중단 후 무유도방식 유도탄의 추력비행단계 유도알고리듬의 설계과정을 다룬다. 유도의 목적은 추력중단 시점에서 요구속도벡터를 성취하기 위한 것이다. 구현 가능한 피치평면 비행궤적을 조사하기 위해 네 가지 성능지수에 대한 비행궤적 최적화를 수행하였다. 궤적최적화 결과로부터 구속조건들을 만족시키기 위해서는 비행초기에 고앙각 기동이 필요함을 알 수 있다. 제안된 유도알고리듬은 개루프 피치자세각 명령 산출기인 피치프로그램과 증가요구속도벡터를 0으로 만들기 위한 요자세각 명령 산출기로 구성된다. 피치프로그램은 궤적최적화 결과 얻어진 피치자세각 선도를 이용하여 구성되었다.