1,721,026 research outputs found
Robust model-based fault diagnosis for unmanned underwater vehicles using sliding mode observers
No full textModeling and identification of open-frame variable configuration unmanned underwater vehicles
No full textA lumped parameter model of open-frame unmanned underwater vehicles (UUV's) including the effects of propeller-hull and propeller-propeller interactions is presented. The identification of the model parameters consists of a least squares method using only on-board sensor data without requiring any towing tank tests. The identification scheme is based on separate tests for the estimation of drag and thruster installation coefficients, taking into account propeller-hull and propeller-propeller effects first and inertia parameters subsequently. The scheme has been experimentally implemented on ROMEO, the latest UUV developed by CNR-IAN. Experimental results show both the effectiveness of the proposed method and the relevance of the propeller-hull and propeller-propeller interactions that are usually neglected in standard UUV models
Experimental comparison of identification methods for an open-frame ROV
No full textThis paper deals with the identification of hydrodynamic derivatives in a Remotely Operated Vehicle (ROV). In-water tests have been performed to identify yaw inertial and drag coefficients on the prototype ROV Roby2, developed at IAN. Vehicle heading has been measured losing a commercial digital fluxgate compass. A least square off line polynomial data fitting technique to compute signal derivatives is applied to experimental compass data. Subsequently, least squares and random-search algorithms are applied to experimental data to identify the vehicle model's coefficients. The experimental set-up and modalities are discussed and results of the least squares and random-research algorithms are compared
Application of LS and EKF Techniques to the Identification of Underwater Vehicles
No full textThe modelling and identification of an open-frame underwater vehicle for marine applications has been considered. The goal of this work is to demonstrate that modelling and identification of small underwater vehicles is feasible at low cost: the identification has been accomplished using only standard on-board devices. First, the selection of a model for such vehicles is discussed, as well as a suitable identification method. The parameters of the selected model have been identified in two steps, based on least squares (LS) and extended Kalman filter (EKF) techniques. The results of the identification applied to experimental data are presented and discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
