• 한국생산제조학회지
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• 제20권4호
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• pp.386-394
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• 2011

This paper is concerned with the application of the vision control scheme for robot's point placement task in discontinuous trajectory caused by obstacle. The proposed vision control scheme consists of four models, which are the robot's kinematic model, vision system model, 6-parameters estimation model, and robot's joint angles estimation model. For this study, the discontinuous trajectory by obstacle is divided into two obstacle regions. Each obstacle region consists of 3 cases, according to the variation of number of cameras that can not acquire the vision data. Then, the effects of number of cameras on the proposed robot's vision control scheme are investigated in each obstacle region. Finally, the practicality of the proposed robot's vision control scheme is demonstrated experimentally by performing the robot's point placement task in discontinuous trajectory by obstacle.

• 스마트미디어저널
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• 제5권4호
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• pp.26-40
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• 2016

최근 모바일 기기가 발전함에 따라 사용자의 위치 수집 및 분석 방법에 대한 연구가 활발히 이루어지고 있다. 사용자의 위치분석 방법 중 궤적 데이터 마이닝은 사용자의 궤적을 바탕으로 의미 있는 정보를 추출하기 위해 사용된다. 궤적 데이터 마이닝을 수행하기 위해서는 사용자의 GPS 궤적을 분석하여 Stay Point를 추출하는 과정이 선행되어야 한다. 기존의 Stay Point 추출 알고리즘은 두 가지의 임계값이 필요하며 해당 임계값들은 사용자가 임의로 설정함으로써 알고리즘의 신뢰도가 떨어지고, 실내에서 머문 지점과 실외에서 머문지점에 대한 구분이 없기 때문에 Stay Point 위치의 모호성이 높아지는 문제점이 있다. 본 논문에서는 통계적 분석방법을 이용하여 SP를 추출하는 방법을 제안한다. 제안 알고리즘은 가우시안 확률분포를 사용하여 실내와 실외 SP를 각각 추출함으로써 SP 위치의 모호성을 개선하였다. 또한, 사용자가 임의로 설정하는 임계값이 없기 때문에 알고리즘의 신뢰도를 향상시켰다.

• 한국군사과학기술학회지
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• 제19권1호
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• pp.95-104
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• 2016

To make a firing table of artillery with trajectory simulation, a precise trajectory model which corresponds with real firing test is required. Recent 4-DOF modified point mass trajectory model is considered accurate as a theoretical model, but fitting coefficients are used in calculation to match with real firing test results. In this paper, modified point mass trajectory model is presented and method of setting ballistic coefficient is introduced by applying optimization algorithms. After comparing two different algorithms, Particle Swarm Optimization and Covariance Matrix Adaptation - Evolutionary Strategy, we found that using CMA-ES algorithm gives fine optimization result. This fitting coefficient setting method can be used to make trajectory simulation which is required for development of new projectiles in the future.

• 한국해양공학회지
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• 제37권3호
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• pp.122-128
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• 2023

Autonomous berthing is a crucial technology for autonomous ships, requiring optimal trajectory planning to prevent collisions and minimize time and control efforts. This paper presents a two-phase, two-point boundary value problem (TPBVP) strategy for creating an optimal berthing trajectory for a twin-propeller, twin-rudder ship with autonomous berthing capabilities. The process is divided into two phases: the approach and the terminal. Tunnel thruster use is limited during the approach but fully employed during the terminal phase. This strategy permits concurrent optimization of the total trajectory duration, individual phase trajectories, and phase transition time. The efficacy of the proposed method is validated through two simulations. The first explores a scenario with phase transition, and the second generates a trajectory relying solely on the approach phase. The results affirm our algorithm's effectiveness in deciding transition necessity, identifying optimal transition timing, and optimizing the trajectory accordingly. The proposed two-phase TPBVP approach holds significant implications for advancements in autonomous ship navigation, enhancing safety and efficiency in berthing operations.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권2호
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• pp.600-619
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• 2015

We propose a cost-efficient hybrid algorithm for online location updates that efficiently combines feature point detection with the online trajectory-based sampling algorithm. Our algorithm is designed to minimize the average trajectory error with the minimal number of sample points. The algorithm is composed of 3 steps. First, we choose corner points from the map as sample points because they will most likely cause fewer trajectory errors. By employing the online trajectory sampling algorithm as the second step, our algorithm detects several missing and important sample points to prevent unwanted trajectory errors. The final step improves cost efficiency by eliminating redundant sample points on straight paths. We evaluate the proposed algorithm with real GPS trajectory data for various bus routes and compare our algorithm with the existing one. Simulation results show that our algorithm decreases the average trajectory error 28% compared to the existing one. In terms of cost efficiency, simulation results show that our algorithm is 29% more cost efficient than the existing one with real GPS trajectory data.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.574-577
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• 2001

This paper presents the comparison of FRI(Foot Rotation Indicator) point and ZMP(Zero Moment Point) in biped robot stability. We showed FRI may be employed as a useful tool in stability analysis in biped robot. Also, we proposed the balancing joint trajectory derived from FRI point equation for stable gait. The numerical calculation routines and walking algorithms for simulation are performed by MATLAB. The procedure is composed of the leg trajectory planning, the generation of balancing trajectory, and the verification of dynamic stability.

• 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.263-266
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• 1996

A method to determine an optimal temperature trajectory that guarantees polymer products having controlled molecular weight distribution and desired values of molecular weight is presented. The coordinate transformation method and the optimal control theory are applied to a batch PMMA polymerization system to calculate the optimal temperature trajectory. Coordinate transformation method converts the original fixed-end-point, free-end-time problem to a free-end-point, fixed-end-time problem. The idea is that by making the reactor temperature track the optimal temperature trajectory one may be able to produce polymer products having the prespecified physical property in a minimum time. The on-line control experiments with the PID control algorithm have been conducted to establish the validity of the scheme proposed in this study. The experimental results show that prespecified polymer product could be obtained with tracking the calculated optimal temperature trajectory.

• 한국시뮬레이션학회논문지
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• 제27권4호
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• pp.1-8
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• 2018

인공지능을 이용하여 목표 지점까지 제어하는 가장 대표적인 방법은 강화학습이다. 하지만 그동안 강화학습을 처리하기 위해서는 구현하기 어렵고 복잡한 연산을 처리해야만 했다. 본 논문에서는 이를 개선한 Proximal Policy Optimization (PPO) 알고리즘을 이용하여 가상환경에서 목표지점에 도달하기 위한 계획된 비행궤적을 찾는 방법을 시뮬레이션 하였다. 또한 외부 환경요소가 비행궤적 학습에 미치는 영항을 알아보기 위하여 궤적의 변화, 보상 값의 영향 및 외부 바람등과 같은 변수를 추가하고 궤적 학습 성능 및 학습 속도에 미치는 영향을 비교 분석을 수행한다. 본 결과를 통하여 에이전트가 다양한 외부환경의 변화에도 계획된 궤적을 찾을 수 있다는 것을 시뮬레이션 결과에 따라 알 수 있었으며, 이는 실제 비행체에 적용할 수 있을 것이다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.311-312
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• 2011

• Journal of Information Processing Systems
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• 제16권4호
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• pp.750-759
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• 2020

The wide application of various integrated location-based services (LBS social) and tourism application (app) has generated a large amount of trajectory space data. The trajectory data are used to identify popular tourist attractions with high density of tourists, and they are of great significance to smart service and emergency management of scenic spots. A hot spot analysis method is proposed, based on spatial clustering of trajectory stop points. The DBSCAN algorithm is studied with fast clustering speed, noise processing and clustering of arbitrary shapes in space. The shortage of parameters is manually selected, and an improved method is proposed to adaptively determine parameters based on statistical distribution characteristics of data. DBSCAN clustering analysis and contrast experiments are carried out for three different datasets of artificial synthetic two-dimensional dataset, four-dimensional Iris real dataset and scenic track retention point. The experiment results show that the method can automatically generate reasonable clustering division, and it is superior to traditional algorithms such as DBSCAN and k-means. Finally, based on the spatial clustering results of the trajectory stay points, the Getis-Ord Gi* hotspot analysis and mapping are conducted in ArcGIS software. The hot spots of different tourist attractions are classified according to the analysis results, and the distribution of popular scenic spots is determined with the actual heat of the scenic spots.