An alternative approach for robot localization inside pipes using RF spatial fadings

Accurate robot localization represents a challenge inside pipes due to the particular conditions that characterize this type of environment. Outdoor techniques (GPS in particular) do not work at all inside metal pipes, while traditional indoor localization methods based on camera or laser sensors do not perform well mainly due to a lack of external illumination and distinctive features along pipes. Moreover, humidity and slippery surfaces make wheel odometry unreliable. In this paper, we estimate the localization of a robot along a pipe with an alternative Radio Frequency (RF) approach. We first analyze wireless propagation in metallic pipes and propose a series of setups that allow us to obtain periodic RF spatial fadings (a sort of standing wave periodic pattern), together with the influence of the antenna position and orientation over these fadings. Subsequently, we propose a discrete RF odometry-like method, by means of counting the fadings while traversing them. The transversal fading analysis (number of antennas and cross-section position) makes it possible to increase the resolution of this method. Lastly, the model of the signal is used in a continuous approach serving as an RF map. The proposed localization methods outperform our previous contributions in terms of resolution, accuracy, reliability and robustness. Experimental results demonstrate the effectiveness of the RF-based strategy without the need for a previously known map of the scenario or any substantial modification of the existing infrastructure

A robust method for approximate visual robot localization in feature-sparse sewer pipes

Buried sewer pipe networks present many challenges for robot localization systems, which require non-standard solutions due to the unique nature of these environments: they cannot receive signals from global positioning systems (GPS) and can also lack visual features necessary for standard visual odometry algorithms. In this paper, we exploit the fact that pipe joints are equally spaced and develop a robot localization method based on pipe joint detection that operates in one degree-of-freedom along the pipe length. Pipe joints are detected in visual images from an on-board forward facing (electro-optical) camera using a bag-of-keypoints visual categorization algorithm, which is trained offline by unsupervised learning from images of sewer pipe joints. We augment the pipe joint detection algorithm with drift correction using vision-based manhole recognition. We evaluated the approach using real-world data recorded from three sewer pipes (of lengths 30, 50 and 90 m) and benchmarked against a standard method for visual odometry (ORB-SLAM3), which demonstrated that our proposed method operates more robustly and accurately in these feature-sparse pipes: ORB-SLAM3 completely failed on one tested pipe due to a lack of visual features and gave a mean absolute error in localization of approximately 12%–20% on the other pipes (and regularly lost track of features, having to re-initialize multiple times), whilst our method worked successfully on all tested pipes and gave a mean absolute error in localization of approximately 2%–4%. In summary, our results highlight an important trade-off between modern visual odometry algorithms that have potentially high precision and estimate full six degree-of-freedom pose but are potentially fragile in feature sparse pipes, versus simpler, approximate localization methods that operate in one degree-of-freedom along the pipe length that are more robust and can lead to substantial improvements in accuracy

Simultaneous localization and mapping for inspection robots in water and sewer pipe networks: a review

At the present time, water and sewer pipe networks are predominantly inspected manually. In the near future, smart cities will perform intelligent autonomous monitoring of buried pipe networks, using teams of small robots. These robots, equipped with all necessary computational facilities and sensors (optical, acoustic, inertial, thermal, pressure and others) will be able to inspect pipes whilst navigating, selflocalising and communicating information about the pipe condition and faults such as leaks or blockages to human operators for monitoring and decision support. The predominantly manual inspection of pipe networks will be replaced with teams of autonomous inspection robots that can operate for long periods of time over a large spatial scale. Reliable autonomous navigation and reporting of faults at this scale requires effective localization and mapping, which is the estimation of the robot’s position and its surrounding environment. This survey presents an overview of state-of-the-art works on robot simultaneous localization and mapping (SLAM) with a focus on water and sewer pipe networks. It considers various aspects of the SLAM problem in pipes, from the motivation, to the water industry requirements, modern SLAM methods, map-types and sensors suited to pipes. Future challenges such as robustness for long term robot operation in pipes are discussed, including how making use of prior knowledge, e.g. geographic information systems (GIS) can be used to build map estimates, and improve the multi-robot SLAM in the pipe environmen

Robot Localization in Tunnel-like Environments.

Los entornos confinados como tuberías, túneles o minas constituyen infraestructuras clave para el desarrollo de las economías de los diferentes países. La existencia de estas infraestructuras conlleva la necesidad de llevar a cabo una serie de tareas de mantenimiento mediante inspecciones regulares para asegurar la integridad estructural de las mismas. Así mismo, existen otras tareas que se tienen que realizar en estos entornos como pueden ser misiones de rescate en caso de accidentes e incluso las propias tareas derivadas de la construcción de los mismos. La duras condiciones de este tipo de entornos, ausencia de luz, polvo, presencia de fluidos e incluso de sustancias tóxicas, hace que la ejecución de las mismas suponga un trabajo tedioso e incluso peligroso para las personas. Todo esto, unido a los continuos avances en las tecnologías robóticas, hacen que los robots sean los dispositivos más adecuados para la realización de estas tareas.Para que un robot pueda desempeñar su cometido de manera autónoma, es fundamental que pueda localizarse de manera precisa, no sólo para poder decidir las acciones a llevar a cabo sino también para poder ubicar de manera inequívoca los posibles daños que se puedan detectar durante las labores de inspección. El problema de la localización ha sido ampliamente estudiado en el mundo de la robótica, existiendo multitud de soluciones tanto para interiores como para exteriores mediante el uso de diferentes sensores y tecnologías. Sin embargo, los entornos tipo túnel presentan una serie de características específicas que hacen que la tarea de localización se convierta en todo un reto. La ausencia de iluminación y de características distinguibles tanto visuales como estructurales, hacen que los métodos tradicionales de localización basados en sensores láser y cámaras no funcionen correctamente. Además, al tratarse de entornos confinados, no es posible utilizar sensores típicos de exteriores como es el caso del GPS. La presencia de fluidos e incluso de superficies irregulares hacen poco fiables los métodos basados en odometría utilizando encoders en las ruedas del robot.Por otra parte, estos entornos presentan un comportamiento peculiar en lo que a la propagación de la señal de radiofrecuencia se refiere. Por un lado, a determinadas frecuencias, se comportan como guías de onda extendiendo el alcance de la comunicación, pero por otro, la señal radio sufre fuertes desvanecimientos o fadings. Trabajos previos han demostrado que es posible obtener fadings periódicos bajo una configuración determinada.Partiendo de estos estudios, en esta tesis se aborda el problema de la localización en tuberías y túneles reaprovechando esta naturaleza periódica de la señal radio. Inicialmente, se propone un método de localización para tuberías metálicas basado en técnicas probabilísticas, utilizando el modelo de propagación de la señal como un mapa de radiofrecuencia. Posteriormente, se aborda la localización en túneles siguiendo una estrategia similar de reaprovechar la naturaleza periódica de la señal y se presenta un método de localización discreta. Yendo un paso más allá, y con el objetivo de mejorar la localización a lo largo del túnel incluyendo otras fuentes de información, se desarrolla un método inspirado en el paradigma del graph-SLAM donde se incorporan los resultados obtenidos de la detección de características discretas proporcionadas por el propio túnel.Para ello, se implementa un sistema de detección que proporciona la posición absoluta de características relevantes de la señal periódica radio. Del mismo modo, se desarrolla un método de detección de características estructurales del túnel (galerías) que devuelve la posición conocida de las mismas. Todos estos resultados se incorporan al grafo como fuentes de información.Los métodos de localización desarrollados a lo largo de la tesis han sido validados con datos recolectados durante experimentos llevados a cabo con plataformas robóticas en escenarios reales: la tubería de Santa Ana en Castillonroy y el túnel ferroviario de Somport.<br /

Propagation, Localization and Navigation in Tunnel-like Environments

La robótica de servicio, entendida como aquella destinada al uso de uno o varios robots con fines de, por ejemplo, vigilancia, rescate e inspecciones, ha ido tomando cada vez más relevancia en los últimos años. Debido a los grandes avances en las distintas áreas de la robótica, los robots han sido capaces de ejecutar satisfactoriamente tareas que resultan peligrosas o incluso imposibles para los humanos, en diversos entornos. Entre ellos, los entornos confinados como túneles, minas y tuberías, han atraído la atención en aplicaciones relacionadas con transporte ferroviario, redes vehiculares, búsqueda y rescate, y vigilancia, tanto en el ámbito civil como militar. En muchas tareas, la utilización de varios robots resulta más provechoso que utilizar sólo uno. Para cooperar, los robots deben intercambiar información sobre el entorno y su propio estado, por lo que la comunicación entre ellos resulta crucial. Debido a la imposibilidad de utilizar redes cableadas entre robots móviles, se despliegan redes inalámbricas. Para determinar la calidad de señal entre dos robots, inicialmente se utilizaban modelos de propagación basados únicamente en la distancia entre ellos. Sin embargo, estas predicciones sólo resultan útiles en exteriores y sin la presencia de obstáculos, que sólo componen una pequeña parte de los escenarios de la robótica de servicio. Mas aún, la naturaleza altamente multi-trayecto de la propagación electromagnética en túneles hace que éstos actúen como guías de onda para cierto rango de frecuencias, extendiendo considerablemente el alcance de comunicación en comparación con entornos exteriores. Sin embargo, la señal se ve afectada con profundos desvanecimientos (llamados fadings en inglés). Esto los convierte en un reto para la robótica que considera la comunicación entre robots como fundamental. Además, la naturaleza hostil de estos entornos, así como también la falta de características visuales y estructurales, dificultan la localización en estos escenarios, cuestión que resulta fundamental para ejecutar con éxito una tarea con un robot. Los métodos de localización utilizados en interiores, como aquellos basados en SLAM visual, resultan imprecisos por la falta de características distintivas para cámaras o lásers, mientras que los sensores utilizados en exteriores, como el GPS, no funcionan dentro de túneles o tuberías. En esta tesis abordamos problemas fundamentales para la robótica con el fin de proporcionar herramientas necesarias para la exploración con robots en entornos tipo túnel, manteniendo la conectividad de la red de comunicaciones formada por varios robots y una estación base. Para ello, primeramente caracterizamos, en términos de propagación, los dos escenarios tipo túnel más comunes: un túnel de hormigón y una tubería metálica. Hacemos énfasis en el fenómeno de los fadings, ya que son el problema más importante a considerar para mantener la comunicación. Posteriormente presentamos una estrategia de navegación para desplegar un equipo de robots en un túnel, lidiando con los fadings para mantener la conectividad de la red formada por los robots. Esta estrategia ha sido validada a través de numerosos experimentos realizados en un túnel real, el túnel de Somport. Luego, abordamos el problema de la localización, proponiendo e implementando una técnica que permite estimar la posición de un robot dentro de una tubería, basada en la periodicidad de los fadings. El método es validado a través de experimentos reales en tuberías de pequeña y grandes dimensiones. Finalmente, proponemos esquemas de diversidad espacial, de forma que se facilita la navegación mientras se mejora la localización.Deploying a team of robots for search and rescue, inspection, or surveillance, has increasingly gained attention in the last years. As a result of the advances in several areas of robotics, robots have been able to successfully execute tasks that are hazardous or even impossible for humans in a variety of scenarios, such as outdoors, indoors, or even underground. Among these scenarios, tunnel-like environments (such as tunnels, mines, or pipes) have attracted attention for train applications, vehicular networks, search and rescue, and even service and surveillance missions in both military and civilian contexts. In most of the tasks, utilizing a multi-robot team yields better results than a singlerobot system, as it makes the system more robust while reducing the time required to complete tasks. In order to cooperate, robots must exchange information about their current state and the surrounding environment, making communication between them a crucial task. However, due to the mobile nature of robots used for exploration, a wired architecture is not possible nor convenient. Instead, a wireless network is often deployed. Wireless propagation in tunnel-like environments, characterized for the presence of strong fading phenomena, differs from regular indoor and outdoor scenarios, posing multiple challenges for communication-aware robotics. In addition, accurate localization is a problem in environments such as tunnels or pipes. These environments generally lack distinctive visual and/or structural features and are longer than they are wide in shape. Standard indoor localization techniques do not perform well in pipelines or tunnels given the lack of exploitable features, while outdoor techniques (GPS in particular) do not work in these scenarios. In this thesis, we address basic robotics-related problems in order to provide some tools necessary for robotics exploration in tunnel-like scenarios under connectivity constraints. In the first part, we characterize, in terms of propagation, two of the most common tunnel-like environments: a pipe and a tunnel. We emphasize the spatial-fadings phenomena, as it is one of the most relevant issues to deal with, in a communications context. Secondly, we present a navigation strategy to deploy a team of robots for tunnel exploration, in particular maintaining network connectivity in the presence of these fadings. Several experiments conducted in a tunnel allow us to validate the connectivity maintenance of the system. Next, we address the localization problem and propose a technique that uses the periodicity of the fadings to estimate the position of the robots from the base station. The method is validated in small-scale and large-scale pipes. Finally, we propose spatial diversity schemes in order to ease the navigation while improving the localization

Sistema trinocular baseado em triangulação inversa para aquisição simultânea da geometria e textura da superfície interna de dutos

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Mecânica, Florianópolis, 2015.Dutos são o meio mais eficaz de transporte de derivados de petróleo e gás natural. Para evitar acidentes neste sistema de transporte ? que causa danos econômicos e ambientais ? estão sujeitos a normas internacionais de inspeção e manutenção, garantindo a integridade e a eficiência do duto. O transporte de líquidos e gases, muitas vezes realizado em elevadas pressão e temperatura, pode causar danos nos dutos. A corrosão e a abrasão são os efeitos que mais têm impacto, expondo a riscos a integridade de dutos em operação. A principal consequência é a diminuição da espessura da parede do duto, tornando-o mais suscetível a trincas e rompimentos. Desta forma, a avaliação da geometria interna do duto tem um caráter essencial nas ações de prevenção. Para este fim, no mercado há várias ferramentas capazes de medir a geometria interna, baseados em diferentes princípios de medição. Porém, além da informação geométrica, a caracterização da textura do duto também é importante, auxiliando na identificação e classificação dos defeitos. A fusão destes dados permite aos inspetores reunir mais informações sobre o estado da parede interna do duto, auxiliando nas tomadas de decisão. Neste sentido, a motivação deste trabalho é a demanda por um sistema de visão computacional que se desloca no interior do duto. O objetivo é projetar, construir e avaliar um sistema óptico de medição composto por múltiplas câmeras para a aquisição de geometria e textura da superfície interna de dutos baseado na projeção inversa usando correlação. O protótipo multicâmera para dutos de 200 mm (8") de diâmetro foi construído para este fim e testado. Os resultados obtidos em laboratório apresentaram erro sistemático de 0,3 mm no valor do raio medido. O sistema é capaz de medir um anel axial de 50 mm por posicionamento. Notou-se também a característica multidiâmetro do sistema, que mede tubos de 150 a 250 mm de diâmetro. As medições possuem resolução angular de 1° e axial de 1 mm, valores que podem ser ajustados dependendo da necessidade na inspeção. O resultado do método é uma nuvem de pontos intrinsecamente organizada numa malha regular usando coordenadas cilíndricas.Abstract : Pipelines are the most efficient way to transport gas and oil products. To ensure integrity, efficiency and avoid accidents in pipelines- that cause economic and environmental damages - they are subjected to international inspection and maintenance standards. The transport of liquids and gases, often at high pressure and temperature, can damage pipelines. Corrosion and abrasion are the damaging agents which have most impact, exposing to risk the integrity of pipelines in operation. The main consequence is the reduction of the pipe wall, making it more sensitive to cracks and leaks. Thus, the evaluation of pipe's internal geometry is an essential prevention issue. There are several inspection tools able to evaluate the internal geometry integrity based on different measuring principles. However, in addition to the geometric data, the characterization of the inner pipe texture is also important. Combination of geometry and surface texture data help the decision making process about the integrity of the internal wall of pipes. The motivation of this work is the demand for a machine vision system that moves inside the pipeline, and helps the identification and localization of internal defects in pipes. The goal is to design, build and evaluate an optical measurement system composed of multiple cameras for the acquisition of geometry and texture of the inner surface of pipelines using object space oriented point selection for correlation. A three camera prototype for pipes of 200 mm (6 ") diameter was built and tested. The results of laboratory experiments presented an systematic error of 0.3 mm in radius values. The system is able to measure a ring with axial length of 50 mm. It is also noteworthy that the prototype is capable of measuring a wide range of diameters (150 mm to 250 mm). Measurements have angular and axial resolution of 1 ° and 1 mm respectively, values that can be adjusted depending on inspection needs. The results produce a point cloud intrinsically organized in a regular mesh using a cylindrical coordinate system

Contemporary Robotics

This book book is a collection of 18 chapters written by internationally recognized experts and well-known professionals of the field. Chapters contribute to diverse facets of contemporary robotics and autonomous systems. The volume is organized in four thematic parts according to the main subjects, regarding the recent advances in the contemporary robotics. The first thematic topics of the book are devoted to the theoretical issues. This includes development of algorithms for automatic trajectory generation using redudancy resolution scheme, intelligent algorithms for robotic grasping, modelling approach for reactive mode handling of flexible manufacturing and design of an advanced controller for robot manipulators. The second part of the book deals with different aspects of robot calibration and sensing. This includes a geometric and treshold calibration of a multiple robotic line-vision system, robot-based inline 2D/3D quality monitoring using picture-giving and laser triangulation, and a study on prospective polymer composite materials for flexible tactile sensors. The third part addresses issues of mobile robots and multi-agent systems, including SLAM of mobile robots based on fusion of odometry and visual data, configuration of a localization system by a team of mobile robots, development of generic real-time motion controller for differential mobile robots, control of fuel cells of mobile robots, modelling of omni-directional wheeled-based robots, building of hunter- hybrid tracking environment, as well as design of a cooperative control in distributed population-based multi-agent approach. The fourth part presents recent approaches and results in humanoid and bioinspirative robotics. It deals with design of adaptive control of anthropomorphic biped gait, building of dynamic-based simulation for humanoid robot walking, building controller for perceptual motor control dynamics of humans and biomimetic approach to control mechatronic structure using smart materials

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