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Your search keyword '"RODRIGUEZ, ALBERTO"' showing total 212 results
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212 results on '"RODRIGUEZ, ALBERTO"'

7. Manipulation of unknown objects via contact configuration regulation

Author

Doshi, Neel, Taylor, Orion, and Rodriguez, Alberto

Subjects
FOS: Computer and information sciences, Computer Science - Robotics, Robotics (cs.RO)
Abstract

We present an approach to robotic manipulation of unknown objects through regulation of the object's contact configuration: the location, geometry, and mode of all contacts between the object, robot, and environment. A contact configuration constrains the forces and motions that can be applied to the object; however, synthesizing these constraints generally requires knowledge of the object's pose and geometry. We develop an object-agnostic approach for estimation and control that circumvents this need. Our framework directly estimates a set of wrench and motion constraints which it uses to regulate the contact configuration. We use this to reactively manipulate unknown planar objects in the gravity plane. A video describing our work can be found on our project page: http://mcube.mit.edu/research/contactConfig.html., Authors contributed equally, names listed in alphabetical order. ICRA 2022

Published
2022

36. A New Methodology for the Assessment of Very Low Concentrations of Cells in Serous Body Fluids Based on the Count of Ultrasound Echoes Backscattered From Cells.

Author

Elvira, Luis, Ibanez Rodriguez, Alberto, Fernandez, Alba, Duran, Carmen, Parrilla Romero, Montserrat, Pose-Diez-de-la-Lastra, Alicia, Bassat, Quique, and Jimenez, Javier

Subjects
*IMAGE analysis, *BODY fluid analysis, *BODY fluids, *ULTRASONIC imaging, *CELL suspensions, *TRANSDUCERS, *SEROUS fluids, *BACKSCATTERING
Abstract

A methodology for the assessment of cell concentration, in the range 5–100 cells/μL, suitable for in vivo analysis of serous body fluids is presented in this work. This methodology is based on the quantitative analysis of ultrasound images obtained from cell suspensions and considers applicability criteria, such as short analysis times, moderate frequency, and absolute concentration estimation, all necessary to deal with the variability of tissues among different patients. Numerical simulations provided the framework to analyze the impact of echo overlapping and the polydispersion of scatterer sizes on the cell concentration estimation. The cell concentration range that can be analyzed as a function of the transducer and emitted waveform used was also discussed. Experiments were conducted to evaluate the performance of the method using 7-μm and 12-μm polystyrene particles in water suspensions in the 5–100 particles/μL range. A single scanning focused transducer working at a central frequency of 20 MHz was used to obtain ultrasound images. The method proposed to estimate the concentration proved to be robust for different particle sizes and variations of gain acquisition settings. The effect of tissues placed in the ultrasound path between the probe and the sample was also investigated using 3-mm-thick tissue mimics. Under this situation, the algorithm was robust for the concentration analysis of 12 μm particle suspensions, yet significant deviations were obtained for the smallest particles. [ABSTRACT FROM AUTHOR]

Published
2021
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49. Improving the Efficiency of SiC-Based Synchronous Boost Converter Under Variable Switching Frequency TCM and Different Input/Output Voltage Ratios.

Author

Rogina, Maria R., Rodriguez, Alberto, Vazquez, Aitor, and Lamar, Diego G.

Subjects
*ROTARY converters, *ZERO voltage switching, *SILICON carbide, *ELECTRIC potential, *LED lighting
Abstract

This article is focused on the design of a high-voltage (800 V) bidirectional boost converter with high efficiency at medium-low power levels. Triangular current mode (TCM) enhances the efficiency of the converter at low power, thanks to soft-switching operation, but it requires variable switching frequency and large current ripple through the inductor. The former can be implemented by using silicon carbide (SiC) mosfets and the latter can be minimized by using interleaved modules. At low power, TCM requires high switching frequency, a minimum negative inductor current, and a minimum deadtime to obtain zero voltage switching. These values vary for different input/output voltage ratios and must be properly selected to reduce deadtime losses, normally neglected in the literature since it is assumed that they have low impact. However, it can be relevant at high frequencies (especially for devices with high reverse conduction voltage drop, such as SiC mosfets). In this article, deadtime losses are included in the proposed losses models and the selection of optimum values of deadtime and minimum inductor current to minimize these deadtime losses are analytically evaluated and experimentally validated. [ABSTRACT FROM AUTHOR]

Published
2019
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