Abstract

Abstract
This paper describes a micro-architecture for a custom programmable FPGA-based processor, with direct support for streaming and vector computations relying on custom cache memory storage. The processor combines a custom data-path with several parallel data ports for accessing operands in streaming mode thus efficiently supporting nested looping constructs found in high-level languages while mitigating the impact on external memory bandwidth. The architecture leverages the strided access patterns of streaming data access using a microcoded sequencer with multi-dimensional nested looping capability. We present synthesis results for the main components of the architecture on a Xilinx's Virtex-4 FPGA device. The results reveal the architecture to be extremely flexible and consume few FPGA resources. © 2011 IEEE.

Abstract

Abstract
This paper describes the full development process of TriMARES, a hybrid AUV/ROV designed to fulfil the requirements of a consortium for the inspection and periodic monitoring of a large dam reservoir. The demand of robotic systems for underwater operations is growing exponentially and there are many scenarios for which the commercial solutions are not adequate. Such was the case with TriMARES, where it was possible to take advantage of previous designs to achieve a custom solution in a short time. We describe the initial requirements for the underwater system, we present the main solutions adopted for the vehicle subsystems, and we provide some data from the first in-water tests, performed only 6 months after the beginning of the project.

Abstract
In this paper, we address the control of a small-sized autonomous underwater vehicle (AUV), the MARES. We focus on the vertical motion of the vehicle while contemplating an alternative actuator configuration which may operate in the presence of a possible fault. We present a method to detect the occurence of a fault and to identify the faulty thruster. In normal operation, the MARES AUV makes use of two through-hull thrusters for accurate vertical positioning. Nevertheless, the vehicle depth is still controllable with only one of these but an adequate operation requires the redefinition of the control law. Two modes of operation are made possible by deriving a new feedback control law for the configuration with only one vertical thruster. Based on the Lyapunov theory and on the backstepping method, we determine a control law that makes the vehicle tend to the reference with null error. As a demonstration of the performances of our approach, we present some results obtained from field experiments.

Abstract
Ocean sewage outfalls are major sources of contaminants to coastal ocean ecosystems. This method of disposal has advantages in terms of economy and relative societal impact, but it also raises important concerns about public health and ecosystem preservation. Autonomous Underwater Vehicles have already been shown to be very useful for monitoring routine of ocean outfalls. The major advantage of this technology over traditional methods is the ability to collect high-resolution data which can be very valuable for environmental impact assessment and comparison with plume prediction models. Once the data has been collected in the field it is necessary to extrapolate from monitoring samples to unsampled locations. Geostatistics has been successfully used to obtain information, for example, regarding the spatial distribution of soil properties. In this work geostatistics is used to model and map the spatial distribution of temperature and salinity measurements gathered by MARES AUV in a monitoring campaign to Foz do Arelho outfall, with the aim of distinguishing the effluent plume from the receiving waters and characterizing its spatial variability in the vicinity of the discharge. The results demonstrate that this methodology provides good estimates of the dispersion of effluent and it is therefore very valuable in assessing the environmental impact and managing sea outfalls.