854 resultados para Underwater exploration
Resumo:
This paper presents the design and implementation of a mission control system (MCS) for an autonomous underwater vehicle (AUV) based on Petri nets. In the proposed approach the Petri nets are used to specify as well as to execute the desired autonomous vehicle mission. The mission is easily described using an imperative programming language called mission control language (MCL) that formally describes the mission execution thread. A mission control language compiler (MCL-C) able to automatically translate the MCL into a Petri net is described and a real-time Petri net player that allows to execute the resulting Petri net onboard an AUV are also presented
Resumo:
In this paper we describe a system for underwater navigation with AUVs in partially structured environments, such as dams, ports or marine platforms. An imaging sonar is used to obtain information about the location of planar structures present in such environments. This information is incorporated into a feature-based SLAM algorithm in a two step process: (I) the full 360deg sonar scan is undistorted (to compensate for vehicle motion), thresholded and segmented to determine which measurements correspond to planar environment features and which should be ignored; and (2) SLAM proceeds once the data association is obtained: both the vehicle motion and the measurements whose correct association has been previously determined are incorporated in the SLAM algorithm. This two step delayed SLAM process allows to robustly determine the feature and vehicle locations in the presence of large amounts of spurious or unrelated measurements that might correspond to boats, rocks, etc. Preliminary experiments show the viability of the proposed approach
Resumo:
This paper describes a navigation system for autonomous underwater vehicles (AUVs) in partially structured environments, such as dams, harbors, marinas or marine platforms. A mechanical scanning imaging sonar is used to obtain information about the location of planar structures present in such environments. A modified version of the Hough transform has been developed to extract line features, together with their uncertainty, from the continuous sonar dataflow. The information obtained is incorporated into a feature-based SLAM algorithm running an Extended Kalman Filter (EKF). Simultaneously, the AUV's position estimate is provided to the feature extraction algorithm to correct the distortions that the vehicle motion produces in the acoustic images. Experiments carried out in a marina located in the Costa Brava (Spain) with the Ictineu AUV show the viability of the proposed approach
Resumo:
This paper presents the distributed environment for virtual and/or real experiments for underwater robots (DEVRE). This environment is composed of a set of processes running on a local area network composed of three sites: 1) the onboard AUV computer; 2) a surface computer used as human-machine interface (HMI); and 3) a computer used for simulating the vehicle dynamics and representing the virtual world. The HMI can be transparently linked to the real sensors and actuators dealing with a real mission. It can also be linked with virtual sensors and virtual actuators, dealing with a virtual mission. The aim of DEVRE is to assist engineers during the software development and testing in the lab prior to real experiments
Resumo:
This paper presents a novel technique to align partial 3D reconstructions of the seabed acquired by a stereo camera mounted on an autonomous underwater vehicle. Vehicle localization and seabed mapping is performed simultaneously by means of an Extended Kalman Filter. Passive landmarks are detected on the images and characterized considering 2D and 3D features. Landmarks are re-observed while the robot is navigating and data association becomes easier but robust. Once the survey is completed, vehicle trajectory is smoothed by a Rauch-Tung-Striebel filter obtaining an even better alignment of the 3D views and yet a large-scale acquisition of the seabed
Resumo:
A visual SLAM system has been implemented and optimised for real-time deployment on an AUV equipped with calibrated stereo cameras. The system incorporates a novel approach to landmark description in which landmarks are local sub maps that consist of a cloud of 3D points and their associated SIFT/SURF descriptors. Landmarks are also sparsely distributed which simplifies and accelerates data association and map updates. In addition to landmark-based localisation the system utilises visual odometry to estimate the pose of the vehicle in 6 degrees of freedom by identifying temporal matches between consecutive local sub maps and computing the motion. Both the extended Kalman filter and unscented Kalman filter have been considered for filtering the observations. The output of the filter is also smoothed using the Rauch-Tung-Striebel (RTS) method to obtain a better alignment of the sequence of local sub maps and to deliver a large-scale 3D acquisition of the surveyed area. Synthetic experiments have been performed using a simulation environment in which ray tracing is used to generate synthetic images for the stereo system
Resumo:
This is a set of videos which explore issues associated with the use of digital video. The videos help bring home the observation that 'piracy' is viewed in many different ways by different people depending upon their context, and the prevailing local laws.
Resumo:
We are creating this share in order to explore links with Blackboard
Resumo:
Resumen tomado del autor. Resumen también en inglés
Resumo:
Resumen tomado del autor. Resumen también en inglés
Resumo:
Resumen en español
Resumo:
Los seres humanos siempre han sentido curiosidad por el espacio y se han preguntado sobre que hay más allá de la Tierra, cómo se aprecia en algunas novelas de ciencia-ficción. Tras explicar el concepto de espacio, se repasa la historia de la exploración y la carrera espaciales, de los cohetes científicos y de sus primeros tripulantes. Por último, se hace un resumen de la preparación física de los astronautas, de las estaciones, satélites y sondas enviadas para la investigación espacial y de su tecnología; pero, también, se mencionan los peligros y desatres que la rodean.
Resumo:
Las imágenes de esta publicación constituyen la representación visual más completa de cada átomo del universo. Organizada por orden de aparición en la tabla periódica, de cada elemento de los ciento dieciocho que la componen se facilitan datos, cifras, propiedades incluyendo el peso atómico, densidad, punto de ebullición y de fusión, valencia, electronegatividad, y el año y lugar en que se descubrió. Fotografías adicionales muestran cada elemento en formas ligeramente alteradas y sus aplicaciones.
Resumo:
Resumen tomado de la publicaci??n
Resumo:
Resumen tomado de la publicaci??n