• 제목/요약/키워드: Time-optimal trajectory

검색결과 128건 처리시간 0.028초

다이나믹 프로그래밍에 의한 두 대의 로보트를 위한 최소시간 경로계획 (A Near Minimum-Time Trajectory Planning for Two Robots Using Dynamic Programming Technique)

  • 이지홍;오영석
    • 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.

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최소시간을 고려한 다관절 로봇의 궤적계획 (Trajectory Planning of Articulated Robots with Minimum-Time Criterion)

  • 최진섭;양성모;강희용
    • 한국정밀공학회지
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    • 제13권6호
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    • pp.122-127
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    • 1996
  • The achievement of the optimal condition for the task of an industrial articulated robot used in many fields is an important problem to improve productivity. In this paper, a minimum-time trajectory for an articulated robot along the specified path is studied and simulated with a proper example. A general dynamic model of manipulator is represented as a function of path distance. Using this model, the velocity is produced as fast as possible at each point along the path. This minimum-time trajectory planning module together with the existing collision-free path planning modules is utilized to design the optimal path planning of robot in cases where obstacles present.

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다자유도 기계 시스템의 모션 제어를 위한 동기된 온라인 궤적 생성 방법 (Synchronized On-line Trajectory Generation Method for Mechanical System with Multiple Degrees-of-Freedom)

  • 원대희;신은철
    • 전기학회논문지
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    • 제66권9호
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    • pp.1385-1391
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    • 2017
  • This work presents a synchronized on-line trajectory generation algorithm for mechanical system with multiple degrees-of-freedom. Proposed algorithm is designed to generate time-optimized trajectories and synchronized trajectories under the constraints such as maximum speed, acceleration, deceleration, non-zero initial velocity, etc. Also, because of small computation time, therefore this can be applied in real-time and it is easier to change the trajectory when an event occurs. We verified the feasibility through various trajectory generation.

위성발사체의 궤적최적화와 최적 유도 알고리듬 설계 (Trajectory Optimization and Optimal Explicit Guidance Algorithm Design for a Satellite Launch Vehicle)

  • 노웅래;김유단;송택렬
    • 제어로봇시스템학회논문지
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    • 제7권2호
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    • pp.173-182
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    • 2001
  • Ascent trajectory optimization and optimal explicit guidance problems for a satellite launch vehicle in a 2-dimensional pitch plane are studied. The trajectory optimization problem with boundary conditions is formulated as a nonlinear programming problem by parameterizing the pitch attitude control variable, and is solved by using the SQP algorithm. The flight constraints such as gravity-turn are imposed. An optimal explicit guidance algorithm in the exoatmospheric phase is also presented, the guidance algorithm provides steering command and time-to-go value directly using the current states of the vehicle and the desired orbit insertion conditions. To verify the optimality and accuracy of the algorithm simulations are performed.

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An Earth-Moon Transfer Trajectory Design and Analysis Considering Spacecraft's Visibility from Daejeon Ground Station at TLI and LOI Maneuvers

  • Woo, Jin;Song, Young-Joo;Park, Sang-Young;Kim, Hae-Dong;Sim, Eun-Sup
    • Journal of Astronomy and Space Sciences
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    • 제27권3호
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    • pp.195-204
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    • 2010
  • The optimal Earth-Moon transfer trajectory considering spacecraft's visibility from the Daejeon ground station visibility at both the trans lunar injection (TLI) and lunar orbit insertion (LOI) maneuvers is designed. Both the TLI and LOI maneuvers are assumed to be impulsive thrust. As the successful execution of the TLI and LOI maneuvers are crucial factors among the various lunar mission parameters, it is necessary to design an optimal lunar transfer trajectory which guarantees the visibility from a specified ground station while executing these maneuvers. The optimal Earth-Moon transfer trajectory is simulated by modifying the Korean Lunar Mission Design Software using Impulsive high Thrust Engine (KLMDS-ITE) which is developed in previous studies. Four different mission scenarios are established and simulated to analyze the effects of the spacecraft's visibility considerations at the TLI and LOI maneuvers. As a result, it is found that the optimal Earth-Moon transfer trajectory, guaranteeing the spacecraft's visibility from Daejeon ground station at both the TLI and LOI maneuvers, can be designed with slight changes in total amount of delta-Vs. About 1% difference is observed with the optimal trajectory when none of the visibility condition is guaranteed, and about 0.04% with the visibility condition is only guaranteed at the time of TLI maneuver. The spacecraft's mass which can delivered to the Moon, when both visibility conditions are secured is shown to be about 534 kg with assumptions of KSLV-2's on-orbit mass about 2.6 tons. To minimize total mission delta-Vs, it is strongly recommended that visibility conditions at both the TLI and LOI maneuvers should be simultaneously implemented to the trajectory optimization algorithm.

다중 경로점 제한 조건하의 헬리콥터의 최적 경로 생성 (Generation of an Optimal Trajectory for Rotorcraft Subject to Multiple Waypoint Constraints)

  • 최기영
    • 한국항공우주학회지
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    • 제31권8호
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    • pp.50-57
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    • 2003
  • 헬리콥터를 공간상에서 비교적 가까운 거리에 불규칙하게 주어진 여러 경로점을 따라 비행하는 것은 아주 실제적인 임무인데 이러한 임무에서 최적의 경로를 찾는 것은 어려운 문제에 속한다. 역제어나 직접법을 사용하는 전통적 접근은, 역제어의 경우에는 전 구간의 경로를 시간의 함수로 미리 설정해야 한다거나, 직접법의 경우 계산시간이 너무 많이 소요 된다는 등의 제약으로 그 활용성이 제한적이었다. 본 논문에서는 최적제어기법을 적용하여 다중경로점이 주어진 문제에 대해 최적경로를 구하는 알고리듬을 개발하고 이를 이용하여 slalom 운동과 전체적으로 곡선이 경로에서 일부구간만 선형으로 주어지는 문제 등에 있어서의 헬리콥터의 최적경로를 구하고 그 효용성을 검증하였다.

이산 비선형 시스템에 대한 유한 임펄스 응답 고정 시간 지연 평활기 (A Finite Impulse Response Fixed-lag Smoother for Discrete-time Nonlinear Systems)

  • 권보규;한세경;한수희
    • 제어로봇시스템학회논문지
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    • 제21권9호
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    • pp.807-810
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    • 2015
  • In this paper, a finite impulse response(FIR) fixed-lag smoother is proposed for discrete-time nonlinear systems. If the actual state trajectory is sufficiently close to the nominal state trajectory, the nonlinear system model can be divided into two parts: The error-state model and the nominal model. The error state can be estimated by adapting the optimal time-varying FIR smoother to the error-state model, and the nominal state can be obtained directly from the nominal trajectory model. Moreover, in order to obtain more robust estimates, the linearization errors are considered as a linear function of the estimation errors. Since the proposed estimator has an FIR structure, the proposed smoother can be expected to have better estimation performance than the IIR-structured estimators in terms of robustness and fast convergence. Additionally the proposed method can give a more general solution than the optimal FIR filtering approach, since the optimal FIR smoother is reduced to the optimal FIR filter by setting the fixed-lag size as zero. To illustrate the performance of the proposed method, simulation results are presented by comparing the method with an optimal FIR filtering approach and linearized Kalman filter.

단일곡률궤적과 칼만필터를 이용한 이동로봇의 동적물체 추종 (Moving Object Following by a Mobile Robot using a Single Curvature Trajectory and Kalman Filters)

  • 임현섭;이동혁;이장명
    • 제어로봇시스템학회논문지
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    • 제19권7호
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    • pp.599-604
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    • 2013
  • Path planning of mobile robots has a purpose to design an optimal path from an initial position to a target point. Minimum driving time, minimum driving distance and minimum driving error might be considered in choosing the optimal path and are correlated to each other. In this paper, an efficient driving trajectory is planned in a real situation where a mobile robot follows a moving object. Position and distance of the moving object are obtained using a web camera, and the rotation angular and linear velocities are estimated using Kalman filters to predict the trajectory of the moving object. Finally, the mobile robot follows the moving object using a single curvature trajectory by estimating the trajectory of the moving object. Using the estimation by Kalman filters and the single curvature in the trajectory planning, the total tracking distance and time saved amounts to about 7%. The effectiveness of the proposed algorithm has been verified through real tracking experiments.

Stabilization and trajectory control of the flexible manipulator with time-varying arm length

  • Park, Chang-Yong;Ono, Toshiro;Sung, Yulwan
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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    • pp.20-23
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    • 1996
  • This paper deals with the flexible manipulator with rotational and translational degrees of freedom, which has an arm of time-varying length with the prismatic joint. The tracking control problem of the flexible manipulator is considered. First we design the controller of the 2-type robust servo system based on the finite horizon optimal control theory for the trajectory planned as a discontinuous velocity. Next, to reduce the tracking error, we use the method of the dynamic programming and of modifying the reference trajectory in time coordinate. The simulation results show that the dynamic modeling is adequate and that the asymptotic stabilization of the flexible manipulator is preserved in spite of nonlinear terms. The PTP control error has been reduced to zero completely, and the trajectory tracking errors are reduced sufficiently by the proposed control method.

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수심 제한을 고려한 수중 글라이더 경로 최적화 (Trajectory Optimization for Underwater Gliders Considering Depth Constraints)

  • 윤석민;김진환
    • 한국해양공학회지
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    • 제28권6호
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    • pp.560-565
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    • 2014
  • In this study, the problem of trajectory optimization for underwater gliders considering depth constraints is discussed. Typically, underwater gliders are controlled to dive and climb in a saw-tooth pattern at constant gliding angles. This approach is effective and close to optimal for deep water applications. However, the optimal path deviates from the saw-tooth path in shallow water conditions. This study focuses on finding more efficient gliding paths that can minimize the traverse time in the horizontal plane when the water depth is limited. The trajectory optimization problem is formulated into a minimum time control problem with inequality path constraints and hydrodynamic drag effects. A numerical approach based on the pseudo-spectral method is adopted as a solution approach, and the simulation results are presented.