992 research outputs found
Perception for detection and grasping
The final publication is available at link.springer.comThis research presents a methodology for the detection of the crawler used in the project AEROARMS. The approach consisted on using a two-step progressive strategy, going from rough detection and tracking, for approximation maneuvers, to an accurate positioning step based on fiducial markers. Two different methods are explained for the first step, one using efficient image segmentation approach; and the second one using Deep Learning techniques to detect the center of the crawler. The fiducial markers are used for precise localization of the crawler in a similar way as explained in earlier chapters. The methods can run in real-time.Peer ReviewedPostprint (author's final draft
Marker based Thermal-Inertial Localization for Aerial Robots in Obscurant Filled Environments
For robotic inspection tasks in known environments fiducial markers provide a
reliable and low-cost solution for robot localization. However, detection of
such markers relies on the quality of RGB camera data, which degrades
significantly in the presence of visual obscurants such as fog and smoke. The
ability to navigate known environments in the presence of obscurants can be
critical for inspection tasks especially, in the aftermath of a disaster.
Addressing such a scenario, this work proposes a method for the design of
fiducial markers to be used with thermal cameras for the pose estimation of
aerial robots. Our low cost markers are designed to work in the long wave
infrared spectrum, which is not affected by the presence of obscurants, and can
be affixed to any object that has measurable temperature difference with
respect to its surroundings. Furthermore, the estimated pose from the fiducial
markers is fused with inertial measurements in an extended Kalman filter to
remove high frequency noise and error present in the fiducial pose estimates.
The proposed markers and the pose estimation method are experimentally
evaluated in an obscurant filled environment using an aerial robot carrying a
thermal camera.Comment: 10 pages, 5 figures, Published in International Symposium on Visual
Computing 201
Contribuciones al uso de marcadores para Navegación Autónoma y Realidad Aumentada
Square planar markers are a widely used tools for localization and tracking due to their low cost and high performance. Many applications in Robotics, Unmanned Vehicles and Augmented Reality employ these markers for camera pose estimation with high accuracy. Nevertheless, marker-based systems are affected by several factors that limit their performance. First, the marker detection process is a time-consuming task, which is intensified as the image size increases. As a consequence, the current high-resolution cameras has weakened the processing efficiency of traditional marker systems. Second, marker detection is affected by the presence of noise, blurring and occlusion. The movement of the camera produces image blurriness, generated even by small movements. Furthermore, the marker may be partially or completely occluded in the image, so that it is no longer detected. This thesis deals with the above limitations, proposing novel methodologies and strategies for successful marker detection improving both the efficiency and robustness of these systems. First, a novel multi-scale approach has been developed to speed up the marker detection process. The method takes advantage of the different resolutions at which the image is represented to predict at runtime the optimal scale for detection and identification, as well as following a corner upsampling strategy necessary for an accurate pose estimation. Second, we introduce a new marker design, Fractal Marker, which using a novel keypoint-based method achieves detection even under severe occlusion, while allowing detection over a wider range of distance than traditional markers. Finally, we propose a new marker detection strategy based on Discriminative Correlation Filters (DCF), where the marker and its corners represented in the frequency domain perform more robust and faster detections than state-ofthe- art methods, even under extreme blur conditions.Los marcadores planos cuadrados son una de las herramientas ampliamente utilizadas para la localización y el tracking debido a su bajo coste y su alto rendimiento. Muchas aplicaciones en Robótica, Vehículos no Tripulados y Realidad Aumentada emplean estos marcadores para estimar con alta precisión la posición de la cámara. Sin embargo, los sistemas basados en marcadores se ven afectados por varios factores que limitan su rendimiento. En primer lugar, el proceso de detección de marcadores es una tarea que requiere mucho tiempo y este incrementa a medida que aumenta el tamaño de la imagen. En consecuencia, las actuales cámaras de alta resolución han debilitado la eficacia del procesamiento de los sistemas de marcadores tradicionales. Por otra parte, la detección de marcadores se ve afectada por la presencia de ruido, desenfoque y oclusión. El movimiento de la cámara produce desenfoque de la imagen, generado incluso por pequeños movimientos. Además, el marcador puede aparecer en la imagen parcial o completamente ocluido, dejando de ser detectado. Esta tesis aborda las limitaciones anteriores, proponiendo metodologías y estrategias novedosas para la correcta detección de marcadores, mejorando así tanto la eficiencia como la robustez de estos sistemas. En primer lugar, se ha desarrollado un novedoso enfoque multiescala para acelerar el proceso de detección de marcadores. El método aprovecha las diferentes resoluciones en las que la imagen está representada para predecir en tiempo de ejecución la escala óptima para la detección e identificación, a la vez que sigue una estrategia de upsampling de las esquinas necesaria para estimar la pose con precisión. En segundo lugar, introducimos un nuevo diseño de marcador, Fractal Marker, que, mediante un método basado en keypoints, logra detecciones incluso en casos de oclusión extrema, al tiempo que permite la detección en un rango de distancias más amplio que los marcadores tradicionales. Por último, proponemos una nueva estrategia de detección de marcadores basada en Discriminate Correlation Filters (DCF), donde el marcador y sus esquinas representadas en el dominio de la frecuencia realizan detecciones más robustas y rápidas que los métodos de referencia, incluso bajo condiciones extremas de emborronamiento
Multi-target Attachment for Surgical Instrument Tracking
The pose estimation of a surgical instrument is a common problem in the new needs of medical science. Many instrument tracking methods use markers with a known geometry that allows for solving the
instrument pose as detected by a camera. However, marker occlusion happens, and it hinders correct pose estimation. In this work, we propose an adaptable multi-target attachment with ArUco markers to solve
occlusion problems on tracking a medical instrument like an ultrasound probe or a scalpel. Our multi-target system allows for precise and redundant real-time pose estimation implemented in OpenCV. Encouraging
results show that the multi-target device may prove useful in the clinical settin
Contribuciones a la estimación de la pose de la cámara en aplicaciones industriales de realidad aumentada
Augmented Reality (AR) aims to complement the visual perception of the user environment superimposing virtual elements. The main challenge of this technology is to combine the virtual and real world in a precise and natural way. To carry out this goal, estimating the user position and orientation in both worlds at all times is a crucial task. Currently, there are numerous techniques and algorithms developed for camera pose estimation. However, the use of synthetic square markers has become the fastest, most robust and simplest solution in these cases. In this scope, a big number of marker detection systems have been developed. Nevertheless, most of them presents some limitations, (1) their unattractive and non-customizable visual appearance prevent their use in industrial products and (2) the detection rate is drastically reduced in presence of noise, blurring and occlusions. In this doctoral dissertation the above-mentioned limitations are addressed. In first place, a comparison has been made between the different marker detection systems currently available in the literature, emphasizing the limitations of each. Secondly, a novel approach to design, detect and track customized markers capable of easily adapting to the visual limitations of commercial products has been developed. In third place, a method that combines the detection of black and white square markers with keypoints and contours has been implemented to estimate the camera position in AR applications. The main motivation of this work is to offer a versatile alternative (based on contours and keypoints) in cases where, due to noise, blurring or occlusions, it is not possible to identify markers in the images. Finally, a method for reconstruction and semantic segmentation of 3D objects using square markers in photogrammetry processes has been presented.La Realidad Aumentada (AR) tiene como objetivo complementar la percepción visual del entorno circunstante al usuario mediante la superposición de elementos virtuales. El principal reto de dicha tecnología se basa en fusionar, de forma precisa y natural, el mundo virtual con el mundo real. Para llevar a cabo dicha tarea, es de vital importancia conocer en todo momento tanto la posición, así como la orientación del usuario en ambos mundos. Actualmente, existen un gran número de técnicas de estimación de pose. No obstante, el uso de marcadores sintéticos cuadrados se ha convertido en la solución más rápida, robusta y sencilla utilizada en estos casos. En este ámbito de estudio, existen un gran número de sistemas de detección de marcadores ampliamente extendidos. Sin embargo, su uso presenta ciertas limitaciones, (1) su aspecto visual, poco atractivo y nada customizable impiden su uso en ciertos productos industriales en donde la personalización comercial es un aspecto crucial y (2) la tasa de detección se ve duramente decrementada ante la presencia de ruido, desenfoques y oclusiones Esta tesis doctoral se ocupa de las limitaciones anteriormente mencionadas. En primer lugar, se ha realizado una comparativa entre los diferentes sistemas de detección de marcadores actualmente en uso, enfatizando las limitaciones de cada uno. En segundo lugar, se ha desarrollado un novedoso enfoque para diseñar, detectar y trackear marcadores personalizados capaces de adaptarse fácilmente a las limitaciones visuales de productos comerciales. En tercer lugar, se ha implementado un método que combina la detección de marcadores cuadrados blancos y negros con keypoints y contornos, para estimar de la posición de la cámara en aplicaciones AR. La principal motivación de este trabajo se basa en ofrecer una alternativa versátil (basada en contornos y keypoints) en aquellos casos donde, por motivos de ruido, desenfoques u oclusiones no sea posible identificar marcadores en las imágenes. Por último, se ha desarrollado un método de reconstrucción y segmentación semántica de objetos 3D utilizando marcadores cuadrados en procesos de fotogrametría
Performance Analysis of Low-Cost Tracking System for Mobile Robots
This paper proposes a reliable and straightforward approach to mobile robots (or moving objects in general) indoor tracking, in order to perform a preliminary study on their dynamics. The main features of this approach are its minimal and low-cost setup and a user-friendly interpretation of the data generated by the ArUco library. By using a commonly available camera, such as a smartphone one or a webcam, and at least one marker for each object that has to be tracked, it is possible to estimate the pose of these markers, with respect to a reference conveniently placed in the environment, in order to produce results that are easily interpretable by a user. This paper presents a simple extension to the ArUco library to generate such user-friendly data, and it provides a performance analysis of this application with static and moving objects, using a smartphone camera to highlight the most notable feature of this solution, but also its limitations
Autonomous Tissue Scanning under Free-Form Motion for Intraoperative Tissue Characterisation
In Minimally Invasive Surgery (MIS), tissue scanning with imaging probes is
required for subsurface visualisation to characterise the state of the tissue.
However, scanning of large tissue surfaces in the presence of deformation is a
challenging task for the surgeon. Recently, robot-assisted local tissue
scanning has been investigated for motion stabilisation of imaging probes to
facilitate the capturing of good quality images and reduce the surgeon's
cognitive load. Nonetheless, these approaches require the tissue surface to be
static or deform with periodic motion. To eliminate these assumptions, we
propose a visual servoing framework for autonomous tissue scanning, able to
deal with free-form tissue deformation. The 3D structure of the surgical scene
is recovered and a feature-based method is proposed to estimate the motion of
the tissue in real-time. A desired scanning trajectory is manually defined on a
reference frame and continuously updated using projective geometry to follow
the tissue motion and control the movement of the robotic arm. The advantage of
the proposed method is that it does not require the learning of the tissue
motion prior to scanning and can deal with free-form deformation. We deployed
this framework on the da Vinci surgical robot using the da Vinci Research Kit
(dVRK) for Ultrasound tissue scanning. Since the framework does not rely on
information from the Ultrasound data, it can be easily extended to other
probe-based imaging modalities.Comment: 7 pages, 5 figures, ICRA 202
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