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Acoustic propagation in the ocean waveguide is characterized by mutual interference between the multiple ray paths connecting a source-receiver pair. In the Russian literature, these interference effects have been distilled mathematically into a single parameter, the so-called waveguide invariant defined as beta. The conventional wisdom is that the numerical value of beta is negative in deep water...
Underwater acoustic channels usually suffer from the extended multipath propagation which causes inter symbol interference (ISI). At the receiving end, serious ISI would result in the decrease of the reliability of underwater acoustic communication systems. In this paper, Turbo equalization is applied to increase the reliability of communication systems. The realization of the channel equalizer in...
Conventional beamforming is robust but suffers from fat beams and high level sidelobes. This paper applies the Lucy-Richardson algorithm to the conventional beam power (versus the complex beam output) similar to image de-blurring, and thus avoid the instability problem of common deconvolution algorithms. The deconvolved beam power yields narrow (high resolution) beams and low sidelobe levels. It is...
Matched field processing (MFP) for passive source localization is a comprehensive application of signal processing techniques in extremely complex environment. In essence, it is a parameter estimation processor by exploiting full wave modeling of acoustic waveguide propagation. Typical MFP performance demonstrates a threshold behavior, that is, below some signal-to-noise ratio (SNR), the mean-square...
Autonomous Underwater Vehicle docking technology is now extensively used in the field of underwater. Vision guidance, as one of its core components, shows a great development prospect. In this paper, a brief description of the vision guidance models and the previous algorithm were described. Both the advantages and disadvantages of that algorithm would be analyzed. By using grey-scale feature analysis,...
We study maximum multi-flow scheduling in an underwater acoustic sensor network. The network consists of underwater sensor nodes and surface gateways. Each sensor node seeks to send data to any of the gateways. The objective is to maximize the sum of the flows that can be finished within a fixed time duration. To address challenges posed by large sound propagation latency, we convert the original...
It is important for sonar systems to distinguish the submerged source from the surface one. Current approaches based on matched field processing, mode scintillation and mode filtering require either precise knowledge of the ocean environment parameters or densely populated hydrophone arrays, and become problematic in practical use. Current waveguide invariant based method, deriving the distribution...
Path following is one of the key technologies of Unmanned Surface Vehicle (USV) to complete mission. The interference of flow is an inevitable environmental factor, the study of the straight path following of USV is aimed at enhancing the anti-interference ability of the path following control algorithm under the disturbance of flow. Based on the mathematical model of motion considering the influence...
This paper presents a bilateral control method of teleoperation for the underwater's complex and dangerous environment. The fuzzy adaptive impedance control is applied to the master robot, the integral sliding mode control is applied to the slave robot. The master and slave robot state observers are designed for the unknown interference. The ratio tracking in force and position from the master robot...
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