A Navegação é um dos maiores problemas na robótica móvel, sua função consiste em guiar o robô em um espaço de trabalho por um caminho plausível durante um determinado intervalo de tempo que o leve de um ponto inicial a um ponto final definido. É possível separar esse processo em vários níveis como, a localização do robô no espaço de trabalho, o planejamento de um caminho admissível, a geração de uma trajetória e por fim o controle desse trajeto. Este trabalho apresenta a proposta de desenvolvimento dos níveis de geração e controle de trajetória para um veículo terrestre de grande porte para uso em ambientes de trabalho semiestruturados, principalmente em ambientes agrícolas. Para tal propósito se utiliza o conceito de trajetórias baseadas em clotóides e predefinidas para um sistema bidimensional (X, Y). O gerador de trajetória proposto neste trabalho determina uma função contínua que considera as restrições cinemáticas e determina o tempo de trabalho, a posição e orientação do robô na posição final. As informações determinadas pela função são utilizadas por um controlador de lógica fuzzy para determinar as velocidades linear e angular do robô. Para validar trajetória planejada e o controlador, foram realizados testes nas plataformas robóticas Helvis-III, um protótipo simples com sistema de esterçamento nas rodas dianteiras estilo Ackermann e o RAM (Robô agrícola Móvel) - um veículo de grande porte com estrutura de esterçamento nas 2 rodas com estilo Ackermann de condução. O sistema demonstra bom desempenho, devido ao fato de que o desvio do caminho mantém uma media de 3 metros em base ao valor real e uma média de 0.5 metros em relação ao calculado, estando dentro dos padrões dos sensores GNSS usados para os testes experimentais. / Navigation is one of the biggest problems in mobile robotics, its ban on guiding the robot in a workspace by a plausible path over a defined interval of time than the level of a starting point and a definite endpoint. It is possible to separate the process at some levels such as the location of the robot in the workspace, the planning of a permissible path, the generation of a path and a process of control of that path. This paper presents a proposal for the development of teaching levels and trajectory control for a large land vehicle for use in semi structured work environments, mainly in agricultural environments. To do this, use the concept of routines in clothoids and predefined for a two-dimensional system (X, Y). The generator of trajectory standard this risk is work in the risk control risk, and the risk and the status of work, the status of the risk and work of the position. As one of the reasons for the function are used by a fuzzy logic controller to determine the linear and angular velocities of the robot. To validate the planned trajectory and controller, they were actually tested on the Helvis-III robotic platforms, a simple prototype with the Ackermann advanced style wheel-arming system and the RAM (Mobile Shared Robot) - a large vehicle with structure of Ackermann style 2-wheel steering. The system should be good performance, by the same of the tracking of average pathways and of three meters in base to value and average of 0.5 meters in body the year, being based on the limits of GNSS used for test experimental tests.

A Navegação é um dos maiores problemas na robótica móvel, sua função consiste em guiar o robô em um espaço de trabalho por um caminho plausível durante um determinado intervalo de tempo que o leve de um ponto inicial a um ponto final definido. É possível separar esse processo em vários níveis como, a localização do robô no espaço de trabalho, o planejamento de um caminho admissível, a geração de uma trajetória e por fim o controle desse trajeto. Este trabalho apresenta a proposta de desenvolvimento dos níveis de geração e controle de trajetória para um veículo terrestre de grande porte para uso em ambientes de trabalho semiestruturados, principalmente em ambientes agrícolas. Para tal propósito se utiliza o conceito de trajetórias baseadas em clotóides e predefinidas para um sistema bidimensional (X, Y). O gerador de trajetória proposto neste trabalho determina uma função contínua que considera as restrições cinemáticas e determina o tempo de trabalho, a posição e orientação do robô na posição final. As informações determinadas pela função são utilizadas por um controlador de lógica fuzzy para determinar as velocidades linear e angular do robô. Para validar trajetória planejada e o controlador, foram realizados testes nas plataformas robóticas Helvis-III, um protótipo simples com sistema de esterçamento nas rodas dianteiras estilo Ackermann e o RAM (Robô agrícola Móvel) - um veículo de grande porte com estrutura de esterçamento nas 2 rodas com estilo Ackermann de condução. O sistema demonstra bom desempenho, devido ao fato de que o desvio do caminho mantém uma media de 3 metros em base ao valor real e uma média de 0.5 metros em relação ao calculado, estando dentro dos padrões dos sensores GNSS usados para os testes experimentais. / Navigation is one of the biggest problems in mobile robotics, its ban on guiding the robot in a workspace by a plausible path over a defined interval of time than the level of a starting point and a definite endpoint. It is possible to separate the process at some levels such as the location of the robot in the workspace, the planning of a permissible path, the generation of a path and a process of control of that path. This paper presents a proposal for the development of teaching levels and trajectory control for a large land vehicle for use in semi structured work environments, mainly in agricultural environments. To do this, use the concept of routines in clothoids and predefined for a two-dimensional system (X, Y). The generator of trajectory standard this risk is work in the risk control risk, and the risk and the status of work, the status of the risk and work of the position. As one of the reasons for the function are used by a fuzzy logic controller to determine the linear and angular velocities of the robot. To validate the planned trajectory and controller, they were actually tested on the Helvis-III robotic platforms, a simple prototype with the Ackermann advanced style wheel-arming system and the RAM (Mobile Shared Robot) - a large vehicle with structure of Ackermann style 2-wheel steering. The system should be good performance, by the same of the tracking of average pathways and of three meters in base to value and average of 0.5 meters in body the year, being based on the limits of GNSS used for test experimental tests.

This thesis presents an integrated framework for online obstacle avoidance of rotary-wing unmanned aerial vehicles (UAVs), which can provide UAVs an obstacle field navigation capability in a partially or completely unknown obstacle-rich environment. The framework is composed of a LIDAR interface, a local obstacle grid generation, a receding horizon (RH) trajectory optimizer, a global shortest path search algorithm, and a climb rate limit detection logic. The key feature of the framework is the use of an optimization-based trajectory generation in which the obstacle avoidance problem is formulated as a nonlinear trajectory optimization problem with state and input constraints over the finite range of the sensor. This local trajectory optimization is combined with a global path search algorithm which provides a useful initial guess to the nonlinear optimization solver. Optimization is the natural process of finding the best trajectory that is dynamically feasible, safe within the vehicle's flight envelope, and collision-free at the same time. The optimal trajectory is continuously updated in real time by the numerical optimization solver, Nonlinear Trajectory Generation (NTG), which is a direct solver based on the spline approximation of trajectory for dynamically flat systems. In fact, the overall approach of this thesis to finding the optimal trajectory is similar to the model predictive control (MPC) or the receding horizon control (RHC), except that this thesis followed a two-layer design; thus, the optimal solution works as a guidance command to be followed by the controller of the vehicle. The framework is implemented in a real-time simulation environment, the Georgia Tech UAV Simulation Tool (GUST), and integrated in the onboard software of the rotary-wing UAV test-bed at Georgia Tech. Initially, the 2D vertical avoidance capability of real obstacles was tested in flight. Then the flight test evaluations were extended to the benchmark tests for 3D avoidance capability over the virtual obstacles, and finally it was demonstrated on real obstacles located at the McKenna MOUT site in Fort Benning, Georgia. Simulations and flight test evaluations demonstrate the feasibility of the developed framework for UAV applications involving low-altitude flight in an urban area.

Challenging science requirements and complex space missions are driving the need for fast and robust space trajectory design and simulation tools. The main aim of this thesis is to develop new and improved high performance algorithms and solution techniques for commonly encountered problems in astrodynamics. Five major problems are considered and their state-of-the art algorithms are systematically improved. Theoretical and methodological improvements are combined with modern computational techniques, resulting in increased algorithm robustness and faster runtime performance. The five selected problems are 1) Multiple revolution Lambert problem, 2) High-fidelity geopotential (gravity field) computation, 3) Ephemeris computation, 4) Fast and accurate sensitivity computation, and 5) High-fidelity multiple spacecraft simulation. The work being presented enjoys applications in a variety of fields like preliminary mission design, high-fidelity trajectory simulation, orbit estimation and numerical optimization. Other fields like space and environmental science to chemical and electrical engineering also stand to benefit.

Su abonentų pozicija geografinėje erdvėje susijusi informacija naudojama labai įvairiose srityse: greitajai pagalbai teikti (112 paslauga), teisėsaugoje, krovinių transportavime (stebima kur šiuo metu yra transportuojami kroviniai), turizme, eismo sąlygų stebėjimui, artimiausių ligoninių, restoranų, lankytinų vietų paieškai, pramogoms, mobiliojo tinklo struktūros planavimui (nustačius kur yra didesnis abonentų susibūrimas, pastatoma daugiau bazinių stočių). Tokia su objektų pozicijomis susijusi informacija kaupiama Judančių Objektų duomenų bazėse (JODB), kuri yra judančių objektų sekimo sistemos dalis. Judančiu objektu laikomas toks objektas, kuris bėgant laikui keičia savo geografinę ir laikinę poziciją trimatėje x,y,t erdvėje. Anksčiau vietos informacijai rinkti buvo naudojama tik GPS technologija. GPS technologijos pagrindinis trūkumas tas, kad ji sunkiai veikia miesto tipo vietovėse ir praktiškai neveikia požeminiuose ir antžeminiuose statiniuose. Tačiau vystantis įvairiomis mobiliosiomis ir bevielėms technologijoms, daugėjant jų naudojimo vietų, atsiranda galimybė tokius duomenis rinkti pasinaudojant ne tik GPS, bet ir GSM, WLAN, Bluetooth ir kitomis bevielėmis technologijomis. Todėl atsiranda galimybė GPS pagalba gautus vietos duomenis patikslinti, papildyti arba netgi, jei nereikalaujama didelio tikslumo, judančių objektų vietą nustatyti be GPS panaudojimo. Stebint judančius objektus „visur ir visada“ kiekvienam objektui susidaro baigtinis pozicijų skaičius per tam... [toliau žr. visą tekstą] / The usage of moving objects location information becomes very popular nowadays. This location information can be used in many places: for emergency purposes, tracking cars with cargos, animal tracking, tourism, etc. The moving object’s positions can be detected using location techniques, such as GPS, GSM, etc. When detected moving object’s position is kept in Moving Object Databases (MODB). When object’s position is detected constantly we get a lot of positions, which represent the movement of particular object. We can call this movement a trajectory. The main problem is that these trajectories are too big to keep them in database, to update them or to make a search among them. That’s why there is a need for effective trajectory compression methods in order to make trajectories smaller without losing the most important object’s movement information. Different location techniques generate different types of trajectories, so each type of trajectory needs a different approach how to apply compression technique to it. The trajectory compression can be applied while generating trajectory or it can be done when the generation of trajectory is finished. There are presented different trajectory compression methods for different location techniques (GPS, GSM) in this work. These methods are incorporated into location data history restoration system in order to apply them for location data compression. In this work statistical methods for evaluation of location data compression... [to full text]

Baigiamajame magistro darbe nagrinėjamas šešiakojo roboto judėjimas. Pateikiami vienos kojos atvirkštinės kinematikos uždavinio sprendimai Denavito ir Hartenbergo bei geometriniu metodais. Analizuojamas vienos kojos trajektorijos sudarymo metodas ir pateikiams jos aprašymo būdas. Pateikiami galimi trajektorijų pavyzdžiai. Sudaroma trikojės roboto eisenos seka bei diagrama. Darbe pateikiamas roboto valdymo algoritmas ir valdymo programa, atsižvelgiant į apibrėžtus variklių valdymo kriterijus. Eksperimentiškai tiriamas roboto judėjimas lygiu paviršiumi taikant trikoję eiseną. Pagal rezultatus koreguojama eisena. Atliekami trajektorijos pakartojimo tikslumo bandymai. Įvertinus rezultatus pateikiamos baigiamojo darbo išvados ir pasiūlymai. / Hexapod robot locomotion is analyzed in this paper. Inverse kinematics solutions are proposed for one leg using Denavit-Hartenberg and geometric methods. Trajectory forming for one leg is analyzed and solution for delineating trajectory is introduced. Possible leg trajectory examples are presented. Tripod gait sequence and diagram is designed for robot. Work presents robot control algorithm and program according to motor control parameters. Robot locomotion over regular terrain using tripod gait is tested. Gait then is corrected according to test results. Tests are made for trajectory repeating accuracy. Conclusions and solutions are made according to results.

In this thesis, the kinematic properties of Single Gimballed Control Moment Gyroscopes (SGCMGs) are investigated. Singularity phenomenon inherent to them is explained. Furthermore, existing steering laws with their derivations are given. A novel steering law is developed that may provide singularity avoidance or may be used for quick transition through a singularity with small torque errors. To avoid singularity angular momentum trajectory of the maneuver is to be simulated in advance for the calculation of singularity free gimbal histories. The steering law, besides accurately generating required torques, also pushes the system to follow trajectories closely if there is a small difference between the planned and the realized momentum histories. Thus, it may be used in a feedback system. Also presented are number of approaches for singularity avoidance or quick transition through a singularity. The application of these ideas to the feedback controlled spacecraft is also presented. Existing steering laws and the proposed method are compared through computer simulations. It is shown that the proposed steering law is very effective in singularity avoidance and quick transition through singularities. Furthermore, the approach is demonstrated to be repeatable even singularity is encountered.

This dissertation is focused on target trajectory identification using CW radar sensor network measuring. An omni-directional radar based on single mixing is considered for measurement in ballistic tunnel, where information about direction of target approaching is a priory known. Applied experimental radar network setup with system controller and acquisition units is demonstrated. Mathematical models and optimized structures have been developed for fitting of system parameters and presented in the theoretical part. The second part is aimed to the multi-trajectory identification. New methodical techniques of this work consist in identification of the points of the closest approach with V model function and utilizing gradient methods for path identification.

<p>The missed-thrust problem is a modern challenge in the field of mission design. While some methods exist to quantify its effects, there still exists room for improvement for algorithms which can fully anticipate and plan for a realistic set of missed-thrust events. The present work investigates the use of machine learning techniques to provide a robust controller for a low-thrust spacecraft. The spacecraft’s thrust vector is provided by a neural network controller which guides the spacecraft to the target along a trajectory that is robust to missed thrust, and the controller does not need to re-optimize any trajectories if it veers off its nominal course. The algorithms used to train the controller to account for missed thrust are supervised learning and neuroevolution. Supervised learning entails showing a neural network many examples of what inputs and outputs should look like, with the network learning over time to duplicate the patterns it has seen. Neuroevolution involves testing many neural networks on a problem, and using the principles of biological evolution and survival of the fittest to produce increasingly competitive networks. Preliminary results show that a controller designed with these methods provides mixed results, but performance can be greatly boosted if the controller’s output is used as an initial guess for an optimizer. With an optimizer, the success rate ranges from around 60% to 96% depending on the problem.</p> <p><br></p> <p>Additionally, this work conducts an analysis of a novel hyperbolic rendezvous strategy which was originally conceived by Dr. Buzz Aldrin. Instead of rendezvousing on the outbound leg of a hyperbolic orbit (traveling away from Earth), the spacecraft performs a rendezvous while on the inbound leg (traveling towards Earth). This allows for a relatively low Delta-v abort option for the spacecraft to return to Earth if a problem arose during rendezvous. Previous work that studied hyperbolic rendezvous has always assumed rendezvous on the outbound leg because the total Delta-v required (total propellant required) for the insertion alone is minimal with this strategy. However, I show that when an abort maneuver is taken into consideration, inserting on the inbound leg is both lower Delta-v overall, and also provides an abort window which is up to a full day longer.</p>

Comme les robots effectuent de plus en plus de tâches en interaction avec l'homme ou dans un environnement humain, ils doivent assurer la sécurité et le confort des hommes. Dans ce contexte, le robot doit adapter son comportement et agir en fonction des évolutions de l'environnement et des activités humaines. Les robots développés sur la base de l'apprentissage ou d'un planificateur de mouvement ne sont pas en mesure de réagir assez rapidement, c'est pourquoi nous proposons d'introduire un contrôleur de trajectoire intermédiaire dans l'architecture logicielle entre le contrôleur bas niveau et le planificateur de plus haut niveau. Le contrôleur de trajectoire que nous proposons est basé sur le concept de générateur de trajectoire en ligne (OTG), il permet de calculer des trajectoires en temps réel et facilite la communication entre les différents éléments, en particulier le planificateur de chemin, le générateur de trajectoire, le détecteur de collision et le contrôleur. Pour éviter de replanifier toute une trajectoire en réaction à un changement induit par un humain, notre contrôleur autorise la déformation locale de la trajectoire et la modification de la loi d'évolution pour accélérer ou décélérer le mouvement. Le contrôleur de trajectoire peut également commuter de la trajectoire initiale vers une nouvelle trajectoire. Les fonctions polynomiales cubiques que nous utilisons pour décrire les trajectoires fournissent des mouvements souples et de la flexibilité sans nécessiter de calculs complexes. De plus, les algorithmes de lissage que nous proposons permettent de produire des mouvements esthétiques ressemblants à ceux des humains. Ce travail, mené dans le cadre du projet ANR ICARO, a été intégré et validé avec les robots KUKA LWR de la plate-forme robotique du LAAS-CNRS. / In order to perform a large variety of tasks in interaction with human or in human environments, a robot needs to guarantee safety and comfort for humans. In this context, the robot shall adapt its behavior and react to the environment changes and human activities. The robots based on learning or motion planning are not able to adapt fast enough, so we propose to use a trajectory controller as an intermediate control layer in the software structure. This intermediate layer exchanges information with the low level controller and the high level planner. The proposed trajectory controller, based on the concept of Online Trajectory Generation (OTG), allows real time computation of trajectories and easy communication with the different components, including path planner, trajectory generator, collision checker and controller. To avoid the replan of an entire trajectory when reacting to a human behaviour change, the controller must allow deforming locally a trajectory or accelerate/decelerate by modifying the time function. The trajectory controller must also accept to switch from an initial trajectory to a new trajectory to follow. Cubic polynomial functions are used to describe trajectories, they provide smoothness, flexibility and computational simplicity. Moreover, to satisfy the objective of aesthetics, smoothing algorithm are proposed to produce human-like motions. This work, conducted as part of the ANR project ICARO, has been integrated and validated on the KUKA LWR robot platform of LAAS-CNRS.