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Publications

Publications by CRAS

2019

PSION: Combining Logical Topology and Physical Layout Optimization for Wavelength-Routed ONoCs

Authors
Truppel, A; Tseng, TM; Bertozzi, D; Alves, JC; Schlichtmann, U;

Publication
PROCEEDINGS OF THE 2019 INTERNATIONAL SYMPOSIUM ON PHYSICAL DESIGN (ISPD '19)

Abstract
Optical Networks-on-Chip (ONoCs) are a promising solution for high-performance multi-core integration with better latency and bandwidth than traditional Electrical NoCs. Wavelength-routed ONoCs (WRONoCs) offer yet additional performance guarantees. However, WRONoC design presents new EDA challenges which have not yet been fully addressed. So far, most topology analysis is abstract, i.e., overlooks layout concerns, while for layout the tools available perform Place & Route (P&R) but no topology optimization. Thus, a need arises for a novel optimization method combining both aspects of WRONoC design. In this paper such a method, PSION, is laid out. When compared to the state-of-the-art design procedure, results show a 1.8x reduction in maximum optical insertion loss.

2019

An Alternative SNR Computation Method for ADC Testing

Authors
Machado da Silva, JM; Carlos Alves, JC;

Publication
2019 XXXIV CONFERENCE ON DESIGN OF CIRCUITS AND INTEGRATED SYSTEMS (DCIS)

Abstract
An alternative approach to compute the signal to noise ratio of analogue to digital converters based on the computation of the cross-correlation coefficient of the captured response is proposed here. It is shown, after simulation and experimental results, that this approach allows obtaining good accuracy results with the added advantages of not requiring coherent sampling and high purity sine wave stimuli.

2019

PSION

Authors
Truppel, A; Tseng, T; Bertozzi, D; Alves, JC; Schlichtmann, U;

Publication
Proceedings of the 2019 International Symposium on Physical Design

Abstract

2019

Altitude control of an underwater vehicle based on computer vision

Authors
Rodrigues, PM; Cruz, NA; Pinto, AM;

Publication
OCEANS 2018 MTS/IEEE Charleston, OCEAN 2018

Abstract
It is common the use of the sonar technology in order acquire and posteriorly control the distance of an underwater vehicle towards an obstacle. Although this solution simplifies the problem and is effective in most cases, it might carry some disadvantages in certain underwater vehicles or conditions. In this work it is presented a system capable of controlling the altitude of an underwater vehicle using computer vision. The sensor capable of computing the distance is composed of a CCD camera and 2 green pointer lasers. Regarding the control of the vehicle, the solution used was based on the switching of two controllers, a velocity controller (based on a PI controller), and a position controller (based on a PD controller). The vehicle chosen to test the developed system was a profiler, which main task is the vertical navigation. The mathematical model was obtained and used in order to validate the controllers designed using the Simulink toolbox from Matlab. It was used a Kalman filter in order to have a better estimation of the state variables (altitude, depth, and velocity). The tests relative to the sensor developed responsible for the acquisition of the altitude showed an average relative error equal to 1 % in the range from 0 to 2.5 m. The UWsim underwater simulation environment was used in order to validate the integration of the system and its performance. © 2018 IEEE.

2019

Optimizing the Power Budget of Hovering AUVs

Authors
Cruz, NA;

Publication
2019 IEEE UNDERWATER TECHNOLOGY (UT)

Abstract
The maximum mission duration and range of an Autonomous Underwater Vehicle are governed by the amount of energy carried on board and the way it is spent during the mission. While an increase in battery capacity and a decrease in electronics demand yield a direct increase in vehicle range, the impact of velocity variation is not so obvious. With slower velocities, most of the energy will be spent in electronics, not in motion, while for faster velocities a lot of energy will be needed to balance drag. Flying-type AUVs have a minimum velocity for the control surfaces to be effective, reducing the range of values for optimization. Hovering type AUVs, on the other hand, are typically slower moving platforms, able to travel at arbitrarily slow velocities. This paper addresses the analysis of the power consumption of hovering type AUVs, providing guidelines and analytical expressions to compute the optimal velocity when the vehicle travels in a single direction, and also when the trajectory is a combination of horizontal and vertical motion.

2019

Pushing for Higher Autonomy and Cooperative Behaviors in Maritime Robotics

Authors
Djapic, V; Curtin, TB; Kirkwood, WJ; Potter, JR; Cruz, NA;

Publication
IEEE JOURNAL OF OCEANIC ENGINEERING

Abstract

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