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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
561

Uma heurística GRASP para o problema de dimensionamento de lotes com múltiplas plantas / A GRASP heuristic for the multi-plant lot sizing problem

Mariá Cristina Vasconcelos Nascimento 28 February 2007 (has links)
O problema de dimensionamento de lotes, objeto desse estudo, considera um ambiente composto por múltiplas plantas independentes, múltiplos itens e múltiplos períodos. O ambiente de produção tem capacidade limitada e as plantas podem produzir os mesmos itens. Cada planta tem uma demanda própria e é permitida a transferência de lotes entre as plantas, o que envolve um certo custo. Este problema tem como caso particular o de dimensionamento de lotes com máquinas paralelas. O objetivo desta dissertação é propor uma heurística baseada na meta-heurística GRASP (Greedy Randomized Adaptive Search Procedures). Além disso, uma estratégia path relinking foi incorporada ao GRASP como uma fase de melhoria do algoritmo. Para verificar a eficiência da heurística proposta, os seus resultados são comparados aos da literatura tanto no caso de máquinas paralelas quanto no de múltiplas plantas. Como resultado, o problema de múltiplas plantas obteve melhores resultados quando comparado aos da heurística da literatura. Com relação ao problema de máquinas paralelas, a heurística proposta se mostrou competitiva / The lot sizing problem, which is the aim of this study, considers an environment consisting of multiple independent plants, multiple items and multiple periods. The production environment has limited capacity and the plants can produce the same items. Each plant has its own demand and the lot transfers between the plants are permitted, which involves a certain cost. This problem has as a particular case the parallel machines lot sizing problem. The objective of this dissertation is to propose a heuristic based on the GRASP (Greedy Randomized Adaptive Search Procedures). Furthermore, a path relinking phase is embedded in the GRASP to obtain better performance. To verify the efficiency of the proposed heuristic, its results were compared with the literature as for the multi-plant as for parallel machines problem. Computational tests showed that the proposed heuristic performed better than other literature heuristic concerning the multiplant problem. Concerning the parallel machines, the heuristic is competitive
562

O papel da prosódia no processamento sintático de sentenças garden-path

Araújo, Vanessa Cristina de 01 March 2013 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-05-13T12:17:42Z No. of bitstreams: 1 vanessacristinadearaujo.pdf: 1306440 bytes, checksum: de01a0603451122bff6ee752d2078172 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-06-27T20:09:58Z (GMT) No. of bitstreams: 1 vanessacristinadearaujo.pdf: 1306440 bytes, checksum: de01a0603451122bff6ee752d2078172 (MD5) / Made available in DSpace on 2016-06-27T20:09:58Z (GMT). No. of bitstreams: 1 vanessacristinadearaujo.pdf: 1306440 bytes, checksum: de01a0603451122bff6ee752d2078172 (MD5) Previous issue date: 2013-03-01 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este estudo tem como objetivo investigar a influência da prosódia no processamento sintático de sentenças que possuem ambiguidades estruturais temporárias, conhecidas na literatura psicolinguística como sentenças Garden-Path. Assim, toma-se como hipótese de trabalho que os ouvintes nativos do Português Brasileiro (doravante PB) utilizam as pistas prosódicas como facilitadoras no processamento sintático das sentenças em estudo. Quanto à abordagem teórica utilizada, assume-se o modelo proposto por Corrêa (2006; 2009) que integra teoria linguística, mais especificamente o Programa Minimalista (CHOMSKY, 1995; 1999) com modelos de processamento linguístico como o Bootstrapping Fonológico (MORGAN & DEMUTH, 1996; CHRISTOPHE et al., 1997). Considera-se ainda a Fonologia Prosódica (NESPOR &VOGEL, 1986) que fundamenta a concepção de interface entre os níveis prosódico e sintático. A fim de encontrar evidências a favor da hipótese assumida neste trabalho, foi desenvolvida uma atividade experimental, tendo como base o estudo de Gayle Dede (2010) em língua inglesa. Ouvintes nativos do PB foram expostos a pares de sentenças lexicalmente idênticas, porém com contornos prosódicos distintos. Nas frases (a) utilizaram-se verbos com dupla transitividade como acordava em “Enquanto a mãe acordava os filhos faziam seu café”, seguidos de expressões que podem ser interpretadas como complementos destes (os filhos no exemplo). Já nas frases (b), utilizaram-se verbos intransitivos como caminhava em “Enquanto a mãe caminhava os filhos faziam seu café”, nas quais as expressões que os seguem não podem ser interpretadas como complementos. Os contornos prosódicos, tanto em (a) quanto em (b), levavam a interpretação da expressão temporariamente ambígua, ora como sujeito do verbo da oração principal (condição (P1)), ora como complemento do verbo da oração subordinada (condição (P2)). Os resultados encontrados vão ao encontro da hipótese inicial de que as pistas prosódicas exercem influência no processamento sintático de sentenças Garden Path. / This study investigates the influence of intonational phrase boundaries on the restriction of the syntactic processing of sentences which have temporary structural ambiguities, known in psycholinguistic literature as Garden Path sentences. The working hypothesis is that native listeners of Brazilian Portuguese (BP) uses prosodic cues, more specifically, phonological phrase boundary cues to facilitate the syntactic processing of these sentences. As for the theoretical approach, we assume the model proposed by Corrêa (2006, 2009) that integrates linguistic theory, specifically the Minimalist Program (CHOMSKY, 1995, 1999) with models of language processing as the Phonological Bootstrapping (MORGAN & DEMUTH, 1996; CHRISTOPHE et al., 1997). We also adopt the conception of interface between the prosodic and syntactic levels proposed by the Prosodic Phonology (Nespor & Vogel, 1986). In order to investigate the role of prosodic cues in the syntactic ambiguity resolution, we developed an experimental activity, based on Gayle Dede experiments (2010). BP native listeners were exposed to pairs of lexically identical sentences but with different prosodic contours. In the sentences (a) intransitive subordinate verbs were followed by plausible direct objects as in While the mother woke up the children prepared the breakfast. In the sentences (b) intransitive subordinate verbs were paired with implausible direct objects as in While the mother walked the children prepared the breakfast. Both sentences were unregistered in two prosodic conditions in which the critical segment (the children) were produced as an direct object of the first verb (P2 condition) or as the subject of the second verb object (P1 condition).The results support our hypothesis that prosodic cues facilitate Garden Path sentence syntactic processing by BP native speakers.
563

Dependência de trajetória no setor elétrico

Müller, Matheus 05 March 2013 (has links)
Made available in DSpace on 2014-08-20T13:45:54Z (GMT). No. of bitstreams: 1 Dissertacao_MATHEUS_MULLER.PDF: 1772402 bytes, checksum: dd5b5ed614a44c1db49b70472cbcf63d (MD5) Previous issue date: 2013-03-05 / The proccess of reform of the electricity industry in Brazil followed the global trend over the years 1990 and materialized in line with market principles. The purpose of social, economic and political state went through a long process of restructuring where new regulatory framework was established for the electricity sector. The logic state back to make room for the competitive logic, a kind of return to the origins of the development of the electrical industry, albeit with a conformation organizational and productive much more dense and complex. It is on this background that focuses the study, with the main objective to analyze national policy of restructuring the electricity sector over the decade from 1990 to 2000, from the approach of path dependence. This analytical method is relevant to show that even the innovative initiatives in terms of public policies carry with them elements of structures, institutions and previous policies that act to reinforce actions already initiated. The results point to a policy of power sector reform marked by continue even after the exhaustion of their models. / O processo de reforma da indústria de eletricidade brasileira acompanhou a tendência mundial ao longo dos anos 1990 e se concretizou em consonância com os princípios de mercado. A finalidade social, econômica e política do Estado passou por longo processo de reestruturação, onde novo marco regulatório foi estabelecido para o setor elétrico. A lógica estatal volta a ceder espaço para a lógica competitiva, numa espécie de retorno às origens do processo de desenvolvimento da indústria elétrica, embora com uma conformação organizacional e produtiva muito mais densa e complexa. É sobre esse panorama que se debruça o estudo, com o objetivo principal de analisar a política nacional de reestruturação do setor elétrico ao longo da década de 1990 e 2000, a partir da abordagem da path dependence. Esse método analítico se torna relevante ao demonstrar que, mesmo as iniciativas inovadoras em termos de políticas públicas carregam consigo elementos de estruturas, instituições e políticas anteriores, que atuam de forma a reforçar ações já iniciadas. Os resultados apontam para uma política de reforma do setor elétrico marcada por continuísmos, mesmo após a exaustão do modelo adotado.
564

Spanneröar och spannervägar

Nilsson, Mikael January 2009 (has links)
In this Master Thesis the possibility to efficiently divide a graph into spanner islands is examined. Spanner islands are islands of the graph that fulfill the spanner condition, that the distance between two nodes via the edges in the graph cannot be too far, regulated by the stretch constant, compared to the Euclidian distance between them. In the resulting division the least number of nodes connecting to other islands is sought-after. Different heuristics are evaluated with the conclusion that for dense graphs a heuristic using MAX-FLOW to divide problematic nodes gives the best result whereas for sparse graphs a heuristic using the single-link clustering method performs best. The problem of finding a spanner path, a path fulfilling the spanner condition, between two nodes is also investigated. The problem is proven to be NP-complete for a graph of size n if the spanner constant is greater than n^(1+1/k)*k^0.5 for some integer k. An algorithm with complexity O(2^(0.822n)) is given. A special type of graph where all the nodes are located on integer locations along the real line is investigated. An algorithm to solve this problem is presented with a complexity of O(2^((c*log n)^2))), where c is a constant depending only on the spanner constant. For instance, the complexity O(2^((5.32*log n)^2))) can be reached for stretch 1.5. / I det här magisterarbetet undersöks om det är möjligt att på ett effektivt sätt dela upp en graf i spanneröar, dvs. öar som uppfyller spanneregenskapen som består i att avståndet mellan två noder via grafens bågar inte får vara för stort i förhållande till det euklidiska avståndet mellan noderna. Att hitta en uppdelning som skapar så få kontaktpunkter mellan öarna som möjligt eftersöks. Ett antal heuristiker testas och utvärderas med resultatet att en heuristik som använder sig av MAX-FLOW för att dela upp noder som bryter mot spannervillkoret presterar bäst för täta grafer medan en heuristik av typ single-link clustering presterar bäst för glesa grafer. I arbetet visas att problemet att finna en spannerväg, en väg där noderna som passeras uppfyller spannervillkoret, mellan två noder i en graf av storlek n är NP-komplett om spannerkonstanten är större än n^(1+1/k)*k^0.5 för något heltal k. En algoritm för att hitta spannervägar med komplexiteten O(2^(0.822n)) presenteras. Ett specialproblem där grafen ligger längs tallinjen och bara har noder på heltalspunkter studeras slutligen och här konstrueras en algoritm med komplexiteten O(2^((c*log n)^2))) där c är en konstant som beror på spannerkonstanten. Till exempel nås O(2^((5.32*log n)^2))) för stretch 1.5.
565

Planification de trajectoire et commande pour les robots mobiles non-holonomes / Path planning and control of non-holonomic mobile robots

Ma, Yingchong 19 December 2013 (has links)
Ce travail propose de nouvelles stratégies pour la planification et le contrôle des robots mobiles non-holonomes, de nouveaux algorithmes sont proposés. Tout d'abord, l'identification des différents modèles cinématiques de robot mobiles est discutée, et le problème est formulé comme l'identification en temps réel du signal de commutation d'un système singulier non-linéaire et à commutation. Deuxièmement, sur la base du modèle identifié, un algorithme de planification locale est proposé, et le contour irrégulier de l' obstacle est représenté par des segments. La trajectoire est obtenue en résolvant un problème de commande optimale avec contraintes. Troisièmement, nous appliquons un contrôleur i-PID pour contrôler le robot mobile non-holonome avec la perturbation dans les mesures. Un paramètre de commutation α est proposé en raison de la particularité du système non-holonome. En plus de notre algorithme de planification proposé, une autre approche de planification en utilisant de champs de potentiels est proposée. La nouvelle fonction de champ de potentiel est en mesure de résoudre les problèmes de minima locaux et de produire des forces lisses pour éviter les oscillations. Enfin, une approche de planification coopérative entre robots est proposée en utilisant les informations locales partagées par chaque robot. Le graphe de visibilité est utilisé pour générer une série d'objectifs intermédiaires qui assureront aux robots d’atteindre l'objectif final, et un algorithme est proposé pour étendre les obstacles et fusionner les obstacles lorsque deux obstacles s'entrecroisent / This PhD thesis is dedicated to the path planning and control strategy for non-holonomic mobile robots. After a review of the recent researches and their features, new path planning algorithms and control strategies are proposed. Firstly, the identification of different mobile robot kinematic models is discussed, robot kinematic models are formulated as a switched singular nonlinear system, and the problem becomes the real-time identification of the switching signal. Secondly, based on the identified model, a local path planning algorithm is proposed, in which the irregular contour of obstacles is represented by segments. The path planning problem is formulated as a constrained receding horizon planning problem and the trajectory is obtained by solving an optimal control problem with constraints. Thirdly, we apply an i-PID controller to control the non-holonomic mobile robot with measurement disturbance. A switching parameter α is proposed because of the particularity of the non-holonomic system. In addition to our proposed path planning algorithm, another path planning approach using potential field is proposed. The modified potential field function, which takes into account the robot orientation and angular velocity, is able to solve local minima problems and produce smooth forces to avoid oscillations. Finally, a cooperative path planning approach between robots is proposed by using the shared local information of each robot. The visibility graph is used to generate a series of intermediate objectives which will guarantee the robots reaching the final objective, and an algorithm is proposed to expand obstacles and merge obstacles when two obstacles intercross
566

Performance comparison of two dynamic shared-path protection algorithms for WDM optical mesh networks

Sharma, Ameeth 26 January 2009 (has links)
Finding an optimal solution to the problem of fast and efficient provisioning of reliable connections and failure recovery in future intelligent optical networks is an ongoing challenge. In this dissertation, we investigate and compare the performance of an adapted shared-path protection algorithm with a more conventional approach; both designed for survivable optical Wavelength Division Multiplexing (WDM) mesh networks. The effect of different classes of service on performance is also investigated. Dedicated path protection is a proactive scheme which reserves spare resources to combat single link failures. Conventional Shared-path Protection (CSP) is desirable due to the efficient utilization of resources which results from the sharing of backup paths. Availability is an important performance assessment factor which measures the probability that a connection is in an operational state at some point in time. It is the instantaneous counterpart of reliability. Therefore, connections that do not meet their availability requirements are considered to be unreliable. Reliability Aware Shared-path Protection (RASP) adopts the advantages of CSP by provisioning reliable connections efficiently, but provides protection for unreliable connections only. With the use of a link disjoint parameter, RASP also permits the routing of partial link disjoint backup paths. A simulation study, which evaluates four performance parameters, is undertaken using a South African mesh network. The parameters that are investigated are: 1. Blocking Probability (BP), which considers the percentage of connection requests that are blocked, 2. Backup Success Ratio (BSR), which considers the number of connections that are successfully provisioned with a backup protection path, 3. Backup Primary Resource Ratio (BPR), which considers the ratio of resources utilized to cater for working traffic to the resources reserved for protection paths and lastly 4. Reliability Satisfaction Ratio (RSR), which evaluates the ratio of provisioned connections that meet their availability requirements to the total number of provisioned connections. Under dynamic traffic conditions with varying network load, simulation results show that RASP can provision reliable connections and satisfy Service Level Agreement (SLA) requirements. A competitive Blocking Probability (BP) and lower Backup Primary Resource Ratio (BPR) signify an improvement in resource utilization efficiency. A higher Backup Success Ratio (BSR) was also achieved under high Quality of Service (QoS) constraints. The significance of different availability requirements is evaluated by creating three categories, high availability, medium availability and low availability. These three categories represent three classes of service, with availability used as the QoS parameter. Within each class, the performance of RASP and CSP is observed and analyzed, using the parameters described above. Results show that both the BP and BPR increase with an increase in the availability requirements. The RSR decreases as the reliability requirements increase and a variation in BSR is also indicated. / Dissertation (MEng)--University of Pretoria, 2009. / Electrical, Electronic and Computer Engineering / unrestricted
567

Dynamic Mission Planning for Unmanned Aerial Vehicles

Rennu, Samantha R. January 2020 (has links)
No description available.
568

Planification de chemin d'hélicoptères sur une architecture hétérogène CPU FPGA haute performance / Path planning on a high performance heterogeneous CPU/FPGA architecture

Souissi, Omar 12 January 2015 (has links)
Les problématiques de sécurité sont aujourd’hui un facteur différentiateur clé dans le secteur aéronautique. Bien que certains systèmes d’assistance aux hélicoptères existent et qu’une partie de la connaissance associée aux situations d’urgence ait pu être identifiée, reste que les travaux antérieurs se limitent pour la plupart à une autonomie de bas niveau. Ainsi la génération d’un plan de vol sous fortes contraintes de temps représente à ce jour une voie d’exploration nouvelle, et un défi technologique essentiel pour l’hélicoptère de demain. A cet égard, AIRBUS HELICOPTERS accorde un fort intérêt à la conception d’un système décisionnel capable de générer des plans de vols en temps réel. L’enjeu de l’intelligence répartie au travers de systèmes décisionnels distribués constitue un axe de recherche fort, et un des contributeurs clés pour un positionnement leader d’AIRBUS HELICOPTERS sur la thématique sécurité. Aujourd’hui, l’étude des systèmes décisionnels embarqués dans les engins volants constitue un défi majeur pour divers groupes de travail académiques et industriels. En effet, la résolution de ce défi fait appel généralement à différentes compétences afin de maîtriser plusieurs aspects du système recouvrant les domaines d’acquisition, d’analyse et de traitement de données. Et ce dans le but de prendre des décisions en temps-réel en prenant en considération plusieurs paramètres contextuels et environnementaux. Les défis scientifiques à contourner dans la présente thèse s’articulent sur deux axes majeurs. Dans un premier temps, il faut proposer une approche complète pour une planification en temps réel d’un plan de vol d’hélicoptères. Permettant à cette dernière de faire face à d’éventuels événements dynamiques tel que l’apparition de nouveaux obstacles ou un changement de mission. Ensuite, nous nous intéressons à une implantation embarquée de la solution proposée sur une architecture hétérogène haute performance. / Security issues are today a key-differentiator in the aviation sector. Indeed, it comes to ensure the safety of expensive equipments but above all to save human lives. In this context, it is necessary to offer an important level of autonomy to helicopters. Although some studies have been carried out in this area, the dynamic generation of a sequence of maneuvers under hard time constraints in an unknown environment still represents a major challenge for many academic and industrial working groups. AIRBUS HELICOPTERS as a leader of helicopters manufacturing, looks forward to integrate an assistance system for mission re-planning in the next generation of aircrafts.The work conducted in this PhD thesis falls within a collaboration between AIRBUS HELICOPTERS and UNIVERSITE DE VALENCIENNES ET DU HAINAUTCAMBRESIS. One of the main purposes of this work is efficient flight plan generation. Indeed, for intelligent assistant systems we need to generate a new path planning inorder to face emergency events such as an equipment failure or adverse weather conditions. The second major objective of this work is the deployment of mission planning tasks onto a high performance architecture CPU/FPGA in order to meet real-time requirements for the dynamic optimization process. In the present work, we first studied efficient flight plan generation. Indeed, we developed efficient and effective algorithms for helicopter path planning. Then, in order to obtain a real-time system, we resolved the problem of scheduling optimization on a heterogeneous architecture CPU / FPGA by proposing several scheduling methods including exact approaches and heuristics.
569

Système de planification de chemins aériens en 3D : préparation de missions et replanification en cas d'urgence / System for 3D flight planning : mission preparation and emergency replanning

Baklouti, Zeineb 13 September 2018 (has links)
L’enjeu de planification de vol à bord d’un hélicoptère en tenant compte des différents paramètres environnementaux constitue un facteur clé dans le secteur aéronautique afin d’assurer une mission en toute sécurité avec un coût réduit. Ce défi concerne à la fois la phase de préparation de la mission sur une station au sol mais aussi en cours de vol pour faire face à un évènement imprévu. Nous citons un premier exemple de mission de type recherche et sauvetage qui dispose d’un temps limité pour localiser et rechercher des personnes en danger. Pour ce faire, le plan de vol généré doit suivre le relief du terrain à des altitudes relativement basses entre des points de passage désignés. L’objectif est de permettre au pilote de localiser une victime dans une durée bornée. Un deuxième type de mission comme l’assistance médicale a la particularité d’assurer un vol qui favorise le confort du passager ainsi qu’une route qui minimise le temps de vol selon la criticité de la situation. Pendant la phase dynamique, lorsqu’il s’agit d’un événement complexe telle qu’une panne moteur, une replanification de la mission devient nécessaire afin de trouver un chemin aérien qui permet d’atterrir en toute sécurité dans les plus brefs délais. Dans un autre exemple comme l’évitement d’obstacle dynamique ou de zone dangereuse, il s’agit de calculer un autre plan de vol pour atteindre la destination. Cependant à ce jour, les pilotes ne bénéficient pas de système d’autoroutage 3D permettant la replanification dynamique de mission face à une situation d’urgence. Face au défi de génération d’un plan de vol optimal, nos réflexions profondes ont abouti à la proposition d’un nouveau système de planification de chemin, pour des aéronefs, dédié à la préparation de mission avant le vol ainsi qu’à la replanification dynamique en cours de vol face à une situation d’urgence. Le système de planification peut être déployé sur une station au sol ou bien intégré comme fonction avionique au sein de l’aéronef. Les résultats obtenus ont abouti à un brevet déposé devant l’INPI et à plusieurs actions de transfert technologique au sein d’Airbus Hélicoptères. Le système s’appuie sur des techniques de discrétisation de l’espace et de calcul du plus court chemin afin de générer automatiquement des solutions flexibles en terme de profil de chemin en respectant plusieurs contraintes liées à l’appareil, le terrain et l’environnement. La solution proposée est générique et capable de s’adapter selon le type de l’aéronef, le type de la mission et la fonction objectif à minimiser. Le système de planification peut offrir des solutions avec différents compromis entre le temps d’exécution et la qualité du chemin selon le temps disponible qui peut être corrélé avec la criticité de la situation. Le fonctionnement du système de planification de chemin se compose principalement de deux phases : le prétraitement et le routage. La phase de prétraitement permet une discrétisation multi-altitude de l’espace 3D selon une précision donnée et la génération automatique d’un graphe de navigation avec une connexité paramétrable. La phase de routage 3D calcule le chemin en prenant en considération un ensemble de contraintes telles que les limitations angulaires en horizontal et en vertical et une fonction objectif à minimiser tels que la distance, le carburant, le temps, etc. Lors de la phase d’exploration du graphe, le système de planification peut communiquer avec le modèle de performance de l’appareil afin de minimiser une fonction coût liée à la performance et de s’assurer au fur et à mesure de la faisabilité de la mission. La génération automatique des plans de vol et la replanification dynamique représentent une brique essentielle pour concevoir des systèmes d’assistance au pilote ainsi que des aéronefs autonomes. / Helicopter flight planning is a key factor in the aeronautics domain in order to ensure a safe mission at a reduced cost taking into consideration different environmental parameters like terrain, weather, emergency situations, etc. This challenge concerns both the mission preparation phase using a ground station and also during the flight to cope with a complex event (mechanical failure, dynamic obstacle, bad weather conditions, etc.). We quote as a first example a Search and Rescue mission that should be performed in limited time to locate persons in danger. To achieve that, the generated flight path must follow the terrain profile at relatively low altitudes crossing the predefined waypoints. The objective is to allow the pilot to locate a victim in a short time. Another example for a mission of medical assistance where the helicopter should ensure the comfort of patients as well as minimizing the flight time to respect critical situations. During the flight, when a complex event occurs such as engine failure, re-planning the mission becomes necessary in order to find a new path that could guarantee safe landing. Unfortunately, pilots do not benefit from an embedded 3D path planning system that enables dynamic mission re-planning in case of emergency. To tackle the challenge of generating an optimal flight plan, we proposed new path planning system dedicated to mission preparation and dynamic path re-planning during critical situations. The planning system can be deployed on a ground station or embedded as an avionic function in the aircraft. The achieved results are registered as a patent at National Institute of Intellectual Property and deployed inside Airbus Helicopters through several technology transfers. The system relies on 3D space discretization and shortest path planning techniques to generate automatically flexible path profiles that respect several. The proposed solution is generic and is able to adapt to the aircraft model, mission and the objective function to be minimized. The path planning system can offer solutions with different tradeoffs between timing and path quality within the available runtime depending on the criticality of the situation. The functioning of the path planning system consists mainly of two phases : preprocessing and routing phase. The preprocessing allows a multi-altitude discretization of the 3D space according to a given precision and generate automatically a navigation graph with a configurable density. The 3D routing phase calculates the path by considering a set of constraints such as horizontal and vertical angular limitations and the objective function such as distance, fuel, time, etc. During the graph exploration phase, the path planning system can communicate with the aircraft performance model to evaluate a given criterion. Automatic flight path generation is an essential building block for designing pilot assistance systems and autonomous aircraft. In summary, we succeeded to reach the industrial expectations namely : the evaluation of mission feasibility, performances improvement, navigation workload reduction, as well as improving the flight safety. In order to realize the proposed solution, we designed a new tool for automatic 3D flight path planning. We named our tool DTANAV : Demonstration Tool for Aircraft NAVigation. It allows to apply the proposed planning process on real scenarios. Through the tool interface, the user has the possibility to set the parameters related to the mission (starting point, end point, aircraft model, navigation ceiling, etc.). Other algorithmic parameters are defined in order to control the quality and the profile of the generated solution.
570

Path Planning and Path Following for an Autonomous GPR Survey Robot

Meedendorp, Maurice January 2022 (has links)
Ground Penetrating Radar (GPR) is a tool for mapping the subsurface in a non-invasive way. GPR surveys are currently carried out manually; a time-consuming, tedious and sometimes dangerous task. This report presents the high-level software components for an autonomous unmanned ground vehicle to conduct GPR surveys. The hardware system is a four-wheel drive, skid steering, battery operated vehicle with integrated GPR equipment. Autonomous surveys are conducted using lidar-inertial odometry with robust path planning, path following and obstacle avoidance capabilities. Evaluation shows that the vehicle is able to autonomously execute a planned survey with high accuracy and stops before collisions occur. This system enables high-frequency surveys to monitor the evolution of an area over time, allows one operator to monitor multiple surveys at once, and facilitates future research into novel survey patterns that are difficult to follow manually

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