Improvement of the odometry accuracy of a crawler vehicle with consideration of slippage

Abstract-Crawler mechanisms have the advantage of stable navigation on uneven terrain; as a result, such mechanisms have been adopted for many types of locomotion of outdoor robots, including "search and rescue robots". However, crawler mechanisms always slip when tracking curved paths, and it generates a large accumulating positioning error in vehicles as opposed to conventional wheeled mobile robots. To measure the velocity of the vehicle correctly and improve the accuracy of the odometry, consideration of crawlers' slippage is very important. In this research, we propose a more accurate odometry method for crawler vehicles. In the proposed method, the vehicle can estimate the slip ratios using information from encoders (attached to the actuators) and gyro-sensors. The validity of the method was confirmed by experiments using our crawler vehicle. I. Introduction Crawler mechanisms offer large advantages for the locomotion of vehicles because of their large contact area, which allows them to adapt to bumpy grounds. Therefore, such mechanisms are used in many robotic vehicles for "search and rescue" applications in disaster areas, such as collapsed buildings, underground stairs, or wide cracks in the ground. Our research group also uses crawler vehicles as research platforms of remote control for search and rescue applications. In this research, we aim to realize multi-vehicle control from a distant location with lowbandwidth communication. In this case, it is impossible to realize a conventional vision-based remote control (in which an operator controls a control-joystick by watching continuous vision information from a camera mounted on the vehicle), because of the low-bandwidth communication. To solve this problem, we proposed another remote control system[1] based on three-dimensional range sensor information, as follows: step1: [vehicle side] Obtaining local 3-dimensional environmental information in the neighborhood of the vehicle (called "3D-info") and sending the information to the operator side step2: [vehicle side] Obtaining the vehicle's position and orientation using an odometry system and sending the information to the operator side step3: [operator side] Displaying the 3D-info on the monitor, and super-imposing the vehicle model on it using the odometry informatio

Ultra-wideband Localization on Manifolds for Autonomous Metal Structure Inspection

A robot that can probabalistically infer its state and uncertainties while exploiting differential geometry is capable of achieving more consistent, more accurate, robust state estimation. It is being proposed that ultra-wideband, a cutting-edge technology, that is also highly unpredictable, can be used to give autonomy to a magnetic-wheeled crawler robot for the application of metal structure inspection. Thus, ultra-wideband technology is evaluated based on its sensitivity to metal surfaces at varying heights, as well as its response to varying grid sizes between receivers in experiments featuring a Turtlebot and an RTK-GPS. Then, a novel methodology for ultra-wideband grid initialization is presented featuring a simulation of a ship hull with an ultra-wideband grid. Finally, a metal structure is considered as a parallelizable manifold with a bivariate b-spline representation, and the matrix exponential correspondence between a Lie group and its Lie algebra for the Special Orthogonal Group is applied within the Extended Kalman Filter framework. These considerations constitute the Manifold Invariant Extended Kalman Filter (M-IEKF), a novel approach to more robust state estimation. The filter is derived, presented, and evaluated in comparison with a modified standard approach: the Manifold-Constrained Extended Kalman Filter (MC-EKF), which uses zero-noise virtual measurements to constrain the state estimate. Then, for a real proof of concept, an experiment using a magnetic-wheeled crawler robot with ultra-wideband localization on a surface consisting of curved metal plates is carried out giving viability to the approach in the real-world application of autonomous metal structure inspection.M.S

A motion planning strategy for the active vision-based mapping of ground-level structures

This paper presents a strategy to guide a mobile ground robot equipped with a camera or depth sensor, in order to autonomously map the visible part of a bounded 3-D structure. We describe motion planning algorithms that determine appropriate successive viewpoints and attempt to fill holes automatically in a point cloud produced by the sensing and perception layer. The emphasis is on accurately reconstructing a 3-D model of a structure of moderate size rather than mapping large open environments, with applications for example in architecture, construction, and inspection. The proposed algorithms do not require any initialization in the form of a mesh model or a bounding box, and the paths generated are well adapted to situations where the vision sensor is used simultaneously for mapping and for localizing the robot, in the absence of additional absolute positioning system. We analyze the coverage properties of our policy, and compare its performance with the classic frontier-based exploration algorithm. We illustrate its efficacy for different structure sizes, levels of localization accuracy, and range of the depth sensor, and validate our design on a real-world experiment

A tool for defining models of generic mobile machines

Tässä työssä esitellään mielivaltaisten liikkuvien työkoneiden nopeaan ja helppoon määrittelyyn tarkoitettu ohjelmisto. Käyttäjä määrittelee työkoneen yksinkertaisen, intuitiivisen 3D-käyttöliittymän avulla. Työkoneen määritelmän perusteella generoidaan sen kinemaattinen malli. Kinemaattisissa laskuissa käytetään uusimpia tutkimustuloksia erilaisten ajoneuvojen kinematiikasta. Generoiduilla kinemaattisilla malleilla voidaan simuloida mielivaltaisia konekonfiguraatioita erillisessä simulaattorimoduulissa, joka luotiin osana tätä työtä. Simulaattori tukee yleisimpiä teollisuudessa käytettyjä liikkuvia konetyyppejä, kuten automaisia, telaketjullisia, runkonivellettyjä tai passiivisesti yhdistettyjä koneita. Simuloidut ajoneuvot voivat myös yhdistellä eri konetyyppejä. Ohjelmistolla generoiduilla kinemaattisilla malleilla simuloidaan erilaisia tosimaailman ajoneuvokonfiguraatioita. Simulaatiotuloksia verrataan oikeista koneista saatuun dataan. Mallien havaitaan olevan tarkkoja ja sopivia erilaisiin tarkoituksiin, jotka vaativat ajoneuvon kinemaattisen mallin.In this thesis work, a software tool for quickly and easily defining a mobile vehicle is presented. Vehicles are defined through a simple, intuitive 3D graphical user interface. Based on the vehicle definition, a kinematic model is generated for the vehicle. The kinematics calculations use state-of-the-art knowledge on the kinematics of different vehicle types. The generated kinematic models can be used in a separate simulator module, also created for this thesis work, to simulate arbitrary vehicle configurations. Supported vehicle types include the most common mobile industrial vehicles, such as car-like, tracked, center-articulated or passively linked vehicles. Simulated vehicles can also be combinations of these types. Kinematic models generated with this software are tested against data sets gained from different real-world vehicle configurations. The models are found to be accurate and suitable for various purposes requiring a kinematic model of a vehicle

A robotic platform for precision agriculture and applications

Agricultural techniques have been improved over the centuries to match with the growing demand of an increase in global population. Farming applications are facing new challenges to satisfy global needs and the recent technology advancements in terms of robotic platforms can be exploited. As the orchard management is one of the most challenging applications because of its tree structure and the required interaction with the environment, it was targeted also by the University of Bologna research group to provide a customized solution addressing new concept for agricultural vehicles. The result of this research has blossomed into a new lightweight tracked vehicle capable of performing autonomous navigation both in the open-filed scenario and while travelling inside orchards for what has been called in-row navigation. The mechanical design concept, together with customized software implementation has been detailed to highlight the strengths of the platform and some further improvements envisioned to improve the overall performances. Static stability testing has proved that the vehicle can withstand steep slopes scenarios. Some improvements have also been investigated to refine the estimation of the slippage that occurs during turning maneuvers and that is typical of skid-steering tracked vehicles. The software architecture has been implemented using the Robot Operating System (ROS) framework, so to exploit community available packages related to common and basic functions, such as sensor interfaces, while allowing dedicated custom implementation of the navigation algorithm developed. Real-world testing inside the university’s experimental orchards have proven the robustness and stability of the solution with more than 800 hours of fieldwork. The vehicle has also enabled a wide range of autonomous tasks such as spraying, mowing, and on-the-field data collection capabilities. The latter can be exploited to automatically estimate relevant orchard properties such as fruit counting and sizing, canopy properties estimation, and autonomous fruit harvesting with post-harvesting estimations.Le tecniche agricole sono state migliorate nel corso dei secoli per soddisfare la crescente domanda di aumento della popolazione mondiale. I recenti progressi tecnologici in termini di piattaforme robotiche possono essere sfruttati in questo contesto. Poiché la gestione del frutteto è una delle applicazioni più impegnative, a causa della sua struttura arborea e della necessaria interazione con l'ambiente, è stata oggetto di ricerca per fornire una soluzione personalizzata che sviluppi un nuovo concetto di veicolo agricolo. Il risultato si è concretizzato in un veicolo cingolato leggero, capace di effettuare una navigazione autonoma sia nello scenario di pieno campo che all'interno dei frutteti (navigazione interfilare). La progettazione meccanica, insieme all'implementazione del software, sono stati dettagliati per evidenziarne i punti di forza, accanto ad alcuni ulteriori miglioramenti previsti per incrementarne le prestazioni complessive. I test di stabilità statica hanno dimostrato che il veicolo può resistere a ripidi pendii. Sono stati inoltre studiati miglioramenti per affinare la stima dello slittamento che si verifica durante le manovre di svolta, tipico dei veicoli cingolati. L'architettura software è stata implementata utilizzando il framework Robot Operating System (ROS), in modo da sfruttare i pacchetti disponibili relativi a componenti base, come le interfacce dei sensori, e consentendo al contempo un'implementazione personalizzata degli algoritmi di navigazione sviluppati. I test in condizioni reali all'interno dei frutteti sperimentali dell'università hanno dimostrato la robustezza e la stabilità della soluzione con oltre 800 ore di lavoro sul campo. Il veicolo ha permesso di attivare e svolgere un'ampia gamma di attività agricole in maniera autonoma, come l'irrorazione, la falciatura e la raccolta di dati sul campo. Questi ultimi possono essere sfruttati per stimare automaticamente le proprietà più rilevanti del frutteto, come il conteggio e la calibratura dei frutti, la stima delle proprietà della chioma e la raccolta autonoma dei frutti con stime post-raccolta

Proceedings of the 9th Conference on Autonomous Robot Systems and Competitions

Welcome to ROBOTICA 2009. This is the 9th edition of the conference on Autonomous Robot Systems and Competitions, the third time with IEEE‐Robotics and Automation Society Technical Co‐Sponsorship. Previous editions were held since 2001 in Guimarães, Aveiro, Porto, Lisboa, Coimbra and Algarve. ROBOTICA 2009 is held on the 7th May, 2009, in Castelo Branco , Portugal. ROBOTICA has received 32 paper submissions, from 10 countries, in South America, Asia and Europe. To evaluate each submission, three reviews by paper were performed by the international program committee. 23 papers were published in the proceedings and presented at the conference. Of these, 14 papers were selected for oral presentation and 9 papers were selected for poster presentation. The global acceptance ratio was 72%. After the conference, eighth papers will be published in the Portuguese journal Robótica, and the best student paper will be published in IEEE Multidisciplinary Engineering Education Magazine. Three prizes will be awarded in the conference for: the best conference paper, the best student paper and the best presentation. The last two, sponsored by the IEEE Education Society ‐ Student Activities Committee. We would like to express our thanks to all participants. First of all to the authors, whose quality work is the essence of this conference. Next, to all the members of the international program committee and reviewers, who helped us with their expertise and valuable time. We would also like to deeply thank the invited speaker, Jean Paul Laumond, LAAS‐CNRS France, for their excellent contribution in the field of humanoid robots. Finally, a word of appreciation for the hard work of the secretariat and volunteers. Our deep gratitude goes to the Scientific Organisations that kindly agreed to sponsor the Conference, and made it come true. We look forward to seeing more results of R&D work on Robotics at ROBOTICA 2010, somewhere in Portugal

Sistemas de suporte à condução autónoma adequados a plataforma robótica 4-wheel skid-steer: percepção, movimento e simulação

As competições de robótica móvel desempenham papel preponderante na difusão da ciência e da engenharia ao público em geral. E também um espaço dedicado ao ensaio e comparação de diferentes estratégias e abordagens aos diversos desafios da robótica móvel. Uma das vertentes que tem reunido maior interesse nos promotores deste género de iniciativas e entre o público em geral são as competições de condução autónoma. Tipicamente as Competi¸c˜oes de Condução Autónoma (CCA) tentam reproduzir um ambiente semelhante a uma estrutura rodoviária tradicional, no qual sistemas autónomos deverão dar resposta a um conjunto variado de desafios que vão desde a deteção da faixa de rodagem `a interação com distintos elementos que compõem uma estrutura rodoviária típica, do planeamento trajetórias à localização. O objectivo desta dissertação de mestrado visa documentar o processo de desenho e concepção de uma plataforma robótica móvel do tipo 4-wheel skid-steer para realização de tarefas de condução autónoma em ambiente estruturado numa pista que pretende replicar uma via de circulação automóvel dotada de sinalética básica e alguns obstáculos. Paralelamente, a dissertação pretende também fazer uma análise qualitativa entre o processo de simulação e a sua transposição para uma plataforma robótica física. inferir sobre a diferenças de performance e de comportamento.Mobile robotics competitions play an important role in the diffusion of science and engineering to the general public. It is also a space dedicated to test and compare different strategies and approaches to several challenges of mobile robotics. One of the aspects that has attracted more the interest of promoters for this kind of initiatives and general public is the autonomous driving competitions. Typically, Autonomous Driving Competitions (CCAs) attempt to replicate an environment similar to a traditional road structure, in which autonomous systems should respond to a wide variety of challenges ranging from lane detection to interaction with distinct elements that exist in a typical road structure, from planning trajectories to location. The aim of this master’s thesis is to document the process of designing and endow a 4-wheel skid-steer mobile robotic platform to carry out autonomous driving tasks in a structured environment on a track that intends to replicate a motorized roadway including signs and obstacles. In parallel, the dissertation also intends to make a qualitative analysis between the simulation process and the transposition of the developed algorithm to a physical robotic platform, analysing the differences in performance and behavior

Robotics 2010

Without a doubt, robotics has made an incredible progress over the last decades. The vision of developing, designing and creating technical systems that help humans to achieve hard and complex tasks, has intelligently led to an incredible variety of solutions. There are barely technical fields that could exhibit more interdisciplinary interconnections like robotics. This fact is generated by highly complex challenges imposed by robotic systems, especially the requirement on intelligent and autonomous operation. This book tries to give an insight into the evolutionary process that takes place in robotics. It provides articles covering a wide range of this exciting area. The progress of technical challenges and concepts may illuminate the relationship between developments that seem to be completely different at first sight. The robotics remains an exciting scientific and engineering field. The community looks optimistically ahead and also looks forward for the future challenges and new development

New Approaches in Automation and Robotics

The book New Approaches in Automation and Robotics offers in 22 chapters a collection of recent developments in automation, robotics as well as control theory. It is dedicated to researchers in science and industry, students, and practicing engineers, who wish to update and enhance their knowledge on modern methods and innovative applications. The authors and editor of this book wish to motivate people, especially under-graduate students, to get involved with the interesting field of robotics and mechatronics. We hope that the ideas and concepts presented in this book are useful for your own work and could contribute to problem solving in similar applications as well. It is clear, however, that the wide area of automation and robotics can only be highlighted at several spots but not completely covered by a single book

Navegación de un robot móvil de configuración diferencial basada en fusión sensorial

Uno de los aspectos esenciales en la robótica móvil es la obtención y procesamiento de la información relativa a la localización del robot en el espacio de movimiento con el fin utilizarla para generar los movimientos deseados del robot. Para esto se busca utilizar la mayor cantidad posible de fuentes de información con el fin de corregir los errores de posición asociados a la presencia de ruido en las mediciones del robot. La fusión de toda esta información en una sola medida que pueda ser utilizada en el control de robot es tema central del presente trabajo en el cual se expone la implementación de una fusión de distintos datos provenientes de sensores para mejorar la navegación en robots móviles con recursos de computación limitados. Para ello, se hace una revisión de las técnicas existentes para la fusión de datos, poniendo especial interés en las correspondientes a filtros de Kalman. Se implementaron y probaron distintos esquemas de fusión de sensores utilizando información proveniente de sensores inerciales comunes de un robot en configuración diferencial (acelerómetros, giroscopios, brújula y encoders). Estas pruebas permitieron obtener el método de fusión de sensores propuesto, el que utiliza un filtro de Kalman junto con la información de un modelo local del robot móvil (modelo dinámico con descomposición por partículas inerciales junto con el modelo cinemático) de un robot móvil diferencial y la información de uno o varios sensores inerciales (según la plataforma). Este método propuesto es muy eficiente en términos de utilización de recursos lo cual permite su implementación en robots con recursos limitados. Además su desempeño es comparable a los esquemas de fusión más complejos que utilizan un modelo no lineal y los filtros de Kalman Extendidos y Unscented tal y como se muestra en los resultados obtenidos. El esquema propuesto se probó ampliamente en distintas plataformas como el robot e-puck, el sensor inercial industrial IG500 y principalmente utilizando el robot móvil LEGO NXT debido a su capacidad de utilizar distintos sensores inerciales, todo esto con el fin de comprobar el buen desempeño del método propuesto.Marin Paniagua, LJ. (2011). Navegación de un robot móvil de configuración diferencial basada en fusión sensorial. http://hdl.handle.net/10251/15617Archivo delegad