• Title/Summary/Keyword: route-following algorithm

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A Study on Ship Route Generation with Deep Q Network and Route Following Control

  • Min-Kyu Kim;Hyeong-Tak Lee
    • Journal of Navigation and Port Research
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    • v.47 no.2
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    • pp.75-84
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    • 2023
  • Ships need to ensure safety during their navigation, which makes route determination highly important. It must be accompanied by a route following controller that can accurately follow the route. This study proposes a method for automatically generating the ship route based on deep reinforcement learning algorithm and following it using a route following controller. To generate a ship route, under keel clearance was applied to secure the ship's safety and navigation chart information was used to apply ship navigation related regulations. For the experiment, a target ship with a draft of 8.23 m was designated. The target route in this study was to depart from Busan port and arrive at the pilot boarding place of the Ulsan port. As a route following controller, a velocity type fuzzy P ID controller that could compensate for the limitation of a linear controller was applied. As a result of using the deep Q network, a route with a total distance of 62.22 km and 81 waypoints was generated. To simplify the route, the Douglas-Peucker algorithm was introduced to reduce the total distance to 55.67 m and the number of way points to 3. After that, an experiment was conducted to follow the path generated by the target ship. Experiment results revealed that the velocity type fuzzy P ID controller had less overshoot and fast settling time. In addition, it had the advantage of reducing the energy loss of the ship because the change in rudder angle was smooth. This study can be used as a basic study of route automatic generation. It suggests a method of combining ship route generation with the route following control.

Development of Route following Algorithm for Application in Collision Avoidance Routes of Maritime Autonomous Surface Ship (자율운항선박의 회피 항로 적용을 위한 항로 추종 알고리즘 개발)

  • Seung-Tae Cha;Yu-jun Jeong
    • Journal of Navigation and Port Research
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    • v.47 no.6
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    • pp.386-393
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    • 2023
  • Recently, the demand for autonomous navigation technology has increased, and related research is also increasing. Autonomous ships generally follow the planned route, calculate the avoidance route according to the risk situation while sailing, and follow a calculated route. In general, an automatic steering device is used to follow the route, and among the operational automatic steering device methods, the route control mode is the most appropriate method to apply to autonomous ships. Therefore, in this study, we developed a route-tracking algorithm to apply an avoidance route using the navigation control mode of an automatic steering device. The algorithm was developed by dividing the straight and turning sections. A performance test was conducted to satisfy the performance suggested by IEC 62065, the relevant international standard, using simulator equipment that had acquired international certification to verify its performance. The results of the performance verification confirmed that the cross-track error, which represents the straight distance between the ship and the route, satisfied the performance standards suggested by IEC 62065 when the ship followed the route.

Damping BGP Route Flaps

  • Duan, Zhenhai;Chandrashekar, Jaideep;Krasky, Jeffrey;Xu, Kuai;Zhang, Zhi-Li
    • Journal of Communications and Networks
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    • v.9 no.4
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    • pp.490-498
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    • 2007
  • BGP route flap damping(RFD) was anecdotally considered to be a key contributor to the stability of the global Internet inter-domain routing system. However, it was recently shown that RFD can incorrectly suppress for substantially long periods of time relatively stable routes, i.e., routes that only fail occasionally. This phenomenon can be attributed to the complex interaction between BGP path exploration and how the RFD algorithm identifies route flaps. In this paper we identify a distinct characteristic of BGP path exploration following a single network event such as a link or router failure. Based on this characteristic, we distinguish BGP route updates during BGP path exploration from route flaps and propose a novel BGP route flap damping algorithm, RFD+. RFD+ has a number of attractive properties in improving Internet routing stability. In particular, it can correctly suppress persistent route flaps without affecting routes that only fail occasionally. In addition to presenting the new algorithm and analyzing its properties, we also perform simulation studies to illustrate the performance of the algorithm.

A study on locomotion of a mobile robot by a pattern recognition (패턴 인식에 의한 이동 로보트의 주행에 관한 연구)

  • 신중섭;정동명;장원석;홍승홍
    • 제어로봇시스템학회:학술대회논문집
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    • 1987.10b
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    • pp.79-82
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    • 1987
  • This paper describes the mobile robot system to recognize the guidance tape, and presents the locomotion algorithm. It is composed of image processing unit, A/ID converter and camera. This system converts video image to binary image by setting an optimal threshold and obtains the parameters to move the robot. The mobile robot moves according to the programmed route in memory. But after recognized the obstacle on the locomotion route, this system constructs the new route and the robot moves following the new route.

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Performance Evaluation of Visual Path Following Algorithm (영상 교시기반 주행 알고리듬 성능 평가)

  • Choi, I-Sak;Ha, Jong-Eun
    • Journal of Institute of Control, Robotics and Systems
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    • v.17 no.9
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    • pp.902-907
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    • 2011
  • In this paper, we deal with performance evaluation of visual path following using 2D and 3D information. Visual path follow first teaches driving path by selecting milestone images then follows the same route by comparing the milestone image and current image. We follow the visual path following algorithm of [8] and [10]. In [8], a robot navigated with 2D image information only. But in [10], local 3D geometries are reconstructed between the milestone images in order to achieve fast feature prediction which allows the recovery from tracking failures. Experimental results including diverse indoor cases show performance of each algorithm.

Improvement of Visual Path Following through Velocity Variation (속도 가변을 통한 영상교시 기반 주행 알고리듬 성능 향상)

  • Choi, I-Sak;Ha, Jong-Eun
    • Journal of Institute of Control, Robotics and Systems
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    • v.17 no.4
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    • pp.375-381
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    • 2011
  • This paper deals with the improvement of visual path following through velocity variation according to the coordinate of feature points. Visual path follow first teaches driving path by selecting milestone images then follows the route by comparing the milestone image and current image. We follow the visual path following algorithm of Chen and Birchfield [8]. In [8], they use fixed translational and rotational velocity. We propose an algorithm that uses different translational velocity according to the driving condition. Translational velocity is adjusted according to the variation of the coordinate of feature points on image. Experimental results including diverse indoor cases show the feasibility of the proposed algorithm.

Moving Path following and High Speed Precision Control of Autonomous Mobile Robot Using Fuzzy (퍼지를 이용한 자율 이동 로봇의 이동 경로 추종 및 고속 정밀 제어)

  • Lee, Won-Ho;Lee, Hyung-Woo;Kim, Sang-Heon;Jung, Jae-Young;Roh, Tae-Jung
    • Journal of the Korean Institute of Intelligent Systems
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    • v.14 no.7
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    • pp.907-913
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    • 2004
  • The major interest of general mobile robot is making a route and following a maked route. But, In the case of robot that is in need of movement of partial high speed, the condition of dynamic limitation is exist, and in these conditions, it demands controlling against movements we want. In this paper, in respect of the following a route at the situation that don't have the environmental map, that is, unknown environments, to prevent the slide of moving robot or the overturn that can happen for it moves fast, we organize the dynamic condition of limitation using the fuzzy logic, and we obtain more safe and fast route tracing ability by changing the standard velocity. Especially, by modeling the line tracing mobile robot, we design the tracing controller against a realtime changing target, and using the fuzzy optimized velocity limitation controller, we confirm that our robot shows its stable tracing ability by limiting its velocity intelligently against the continuously changing line.

A Study on locomotion of a mobile robot by a visual perception (시각정보에 의한 이동 로보트의 주행에 관한 연구)

  • Shin, J.S.;Jeong, D.M.;Cho, J.M.;Chang, W.S.;Hong, S.H.
    • Proceedings of the KIEE Conference
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    • 1987.07b
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    • pp.1260-1263
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    • 1987
  • This paper describes the mobile robot system to recognize the guidance tape, and presents the locomotion algorithm. This system converts video imago to binary image by setting an optimal threshold and obtains the parameters to move the robot. The mobile robot moves according to the programmed route in memory. But after recognized the obstacle on the locomotion routs, this system constructs the new route and the robot moves following the new route.

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Intelligent Optimal Route Planning Based on Context Awareness (상황인식 기반 지능형 최적 경로계획)

  • Lee, Hyun-Jung;Chang, Yong-Sik
    • Asia pacific journal of information systems
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    • v.19 no.2
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    • pp.117-137
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    • 2009
  • Recently, intelligent traffic information systems have enabled people to forecast traffic conditions before hitting the road. These convenient systems operate on the basis of data reflecting current road and traffic conditions as well as distance-based data between locations. Thanks to the rapid development of ubiquitous computing, tremendous context data have become readily available making vehicle route planning easier than ever. Previous research in relation to optimization of vehicle route planning merely focused on finding the optimal distance between locations. Contexts reflecting the road and traffic conditions were then not seriously treated as a way to resolve the optimal routing problems based on distance-based route planning, because this kind of information does not have much significant impact on traffic routing until a a complex traffic situation arises. Further, it was also not easy to take into full account the traffic contexts for resolving optimal routing problems because predicting the dynamic traffic situations was regarded a daunting task. However, with rapid increase in traffic complexity the importance of developing contexts reflecting data related to moving costs has emerged. Hence, this research proposes a framework designed to resolve an optimal route planning problem by taking full account of additional moving cost such as road traffic cost and weather cost, among others. Recent technological development particularly in the ubiquitous computing environment has facilitated the collection of such data. This framework is based on the contexts of time, traffic, and environment, which addresses the following issues. First, we clarify and classify the diverse contexts that affect a vehicle's velocity and estimates the optimization of moving cost based on dynamic programming that accounts for the context cost according to the variance of contexts. Second, the velocity reduction rate is applied to find the optimal route (shortest path) using the context data on the current traffic condition. The velocity reduction rate infers to the degree of possible velocity including moving vehicles' considerable road and traffic contexts, indicating the statistical or experimental data. Knowledge generated in this papercan be referenced by several organizations which deal with road and traffic data. Third, in experimentation, we evaluate the effectiveness of the proposed context-based optimal route (shortest path) between locations by comparing it to the previously used distance-based shortest path. A vehicles' optimal route might change due to its diverse velocity caused by unexpected but potential dynamic situations depending on the road condition. This study includes such context variables as 'road congestion', 'work', 'accident', and 'weather' which can alter the traffic condition. The contexts can affect moving vehicle's velocity on the road. Since these context variables except for 'weather' are related to road conditions, relevant data were provided by the Korea Expressway Corporation. The 'weather'-related data were attained from the Korea Meteorological Administration. The aware contexts are classified contexts causing reduction of vehicles' velocity which determines the velocity reduction rate. To find the optimal route (shortest path), we introduced the velocity reduction rate in the context for calculating a vehicle's velocity reflecting composite contexts when one event synchronizes with another. We then proposed a context-based optimal route (shortest path) algorithm based on the dynamic programming. The algorithm is composed of three steps. In the first initialization step, departure and destination locations are given, and the path step is initialized as 0. In the second step, moving costs including composite contexts into account between locations on path are estimated using the velocity reduction rate by context as increasing path steps. In the third step, the optimal route (shortest path) is retrieved through back-tracking. In the provided research model, we designed a framework to account for context awareness, moving cost estimation (taking both composite and single contexts into account), and optimal route (shortest path) algorithm (based on dynamic programming). Through illustrative experimentation using the Wilcoxon signed rank test, we proved that context-based route planning is much more effective than distance-based route planning., In addition, we found that the optimal solution (shortest paths) through the distance-based route planning might not be optimized in real situation because road condition is very dynamic and unpredictable while affecting most vehicles' moving costs. For further study, while more information is needed for a more accurate estimation of moving vehicles' costs, this study still stands viable in the applications to reduce moving costs by effective route planning. For instance, it could be applied to deliverers' decision making to enhance their decision satisfaction when they meet unpredictable dynamic situations in moving vehicles on the road. Overall, we conclude that taking into account the contexts as a part of costs is a meaningful and sensible approach to in resolving the optimal route problem.

Structural Analysis and Dynamic Design Optimization of a High Speed Multi-head Router Machine (다두 Router Machine 구조물의 경량 고강성화 최적설계)

  • 최영휴;장성현;하종식;조용주
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.10a
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    • pp.902-907
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    • 2004
  • In this paper, a multi-step optimization using a G.A. (Genetic Algorithm) with variable penalty function is introduced to the structural design optimization of a 5-head route machine. Our design procedure consist of two design optimization stage. The first stage of the design optimization is static design optimization. The following stage is dynamic design optimization stage. In the static optimization stage, the static compliance and weight of the structure are minimized simultaneously under some dimensional constraints and deflection limits. On the other hand, the dynamic compliance and the weight of the machine structure are minimized simultaneously in the dynamic design optimization stage. As the results, dynamic compliance of the 5-head router machine was decreased by about 37% and the weight of the structure was decreased by 4.48% respectively compared with the simplified structure model.

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