Presentaciones a Congresos

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7-Level asymmetric multilevel current source inverter with predictive control
(2018-01) Cossutta, Pablo; Aguirre, Miguel Pablo; Muñoz, Javier; Rivera, Marco; Melín, Pedro; Rohten, Jaime
"In this paper a 7-Level Asymmetric Multilevel Current Source Inverter is presented. The topology considers two Current Source Inverters that follow a 1:2 ratio to generate the multilevel current waveform. A Model Predictive Control is used to track the internal current and voltage references as well as to keep the asymmetric ratio between the DC currents even during transient conditions. To properly use the predictive algorithm, the modelling equations of the presented topology are systematically obtained in continuous and discrete time domains, considering the characteristic constraints of a Current Source Inverter. Simulated dynamic tests are presented in order to prove the feasibility of the asymmetric approach and the properness of the predictive control technique."
Advertise your A/D converter, a SP teaching strategy
(2010-03) Saint-Nom, Roxana
"The goal of this paper is to invite the reader to consider role-playing as a method to train Signal Processing students for professional functions they would undertake in their future careers. Interaction, communication skills and learning purposes of SP concepts are key elements of this approach. An example applied to Analog to Digital converters is detailed, to show the advantages of this technique and the enthusiasm awakened."
Autonomous vehicles for outdoor multidomain mapping
(2018-06) Garberoglio, Leonardo; Moreno, Patricio; Mas, Ignacio; Giribet, Juan I.
"In the last years, progress has been made attempting to replace a unique, complex and expensive vehicle equipped with several sensors such as LIDAR, RGB cameras, thermal sensor, etc. with a group of small vehicles, each of them carrying one sensor. There are several advantages of these segmented architectures, for instance this allows a reduction in the cost of the vehicles (several small vehicles can be less expensive than one big vehicle), the flexibility to choose for a mission only those vehicles with the appropriate sensors, the robustness of the system since it can acquire information even if one vehicle fails, among others. The advantage of segmented architectures is even more noticeable if the vehicles carrying those different sensors, have different characteristics or environments for operations, e.g. aerial, terrestrial or aquatic vehicles. In this work, we present the experimental results obtained with an ASV (Autonomous Surface Vehicle) and a UAV (Unmanned Aerial Vehicle) that cooperate to obtain a topographic survey of the terrain. The ASV is equipped with a LIDAR, meanwhile the UAV is equipped with a monocular RGB camera. The data acquired is post-processed in order to obtain a detailed map of the coastline of a creek and the surrounding area."
A chopped front-end system with common-mode feedback for real time ECG applications
(2017) Gardella, Pablo; Villa Fernández, Emanuel; Baez, Eduardo; Cesaretti, Juan Manuel
"A Front-End system composed of an instrumentation amplifier with common-mode feedback and a second-order sigma-delta analog to digital converter is proposed. Chopping techniques are used to remove offset and low frequency noise to guarantee a noise floor below the signal of interest. Measurements show that common-mode feedback adds 71 dB to the CMRR at 50 Hz and the input referred noise is 1.17 μVRMS over the frequency range of 0.1 Hz to 400 Hz."
Cluster space LPV control of robot formations
(2018-10) Ghersin, Alejandro S.; Giribet, Juan I.; Mas, Ignacio
"Within the Cluster Space robot formation control scheme, a new approach is presented where a cascaded control scheme is proposed. On one hand, a simple secondary (inner) loop is used to control the formation’s velocity in Robot Space, while on the other hand a quasi-LPV (Linear Parameter Varying) approach is employed for the design of the main (outer) control loop where the geometry and kinematics of the problem are captured by the LPV formulation. Certain aspects of the design such as stability are tackled, and the use of parameter-dependent weighting functions is discussed through a design example tested in simulations in order to illustrate the use of the method."
Coordinated ASV-UAV control for marine collision-free navigation
(2019-09) Garberoglio, Leonardo; Mas, Ignacio; Giribet, Juan I.
"There is an increasing interest in replacing a unique, complex, and expensive vehicle equipped with several sensors with a group of small vehicles, each of them carrying fewer sensors. There are several advantages in these segmented architectures, such as cost, flexibility, redundancy, and robustness, among others. The advantage of segmented architectures is even more noticeable if the vehicles carrying those sensors have different characteristics or environments of operation, e.g. aerial, terrestrial or marine vehicles. This work proposes a multi-robot system where an autonomous marine vehicle avoids obstacles relying on aerial images provided by an autonomous flying vehicle. Both robots navigate in a coordinated fashion increasing the detection area and allowing to adjust the obstacle detection horizon. In order to validate the control scheme two simulation scenarios are presented."
Design of ESD protections for ECG applications
(2020-02) Gardella, Pablo; Baez, Eduardo; Cesaretti, Juan Manuel
"This paper presents the design of Electrostatic Discharge (ESD) protections for a remote Electroencephalograph (ECG). Design and layout guidelines are analyzed to improve the ESD robustness of a Grounded-Gate NMOS (GGNMOS) cell based on a single well CMOS-only process. Experimental validation is done by means of a Time Domain Reflectometry (TDR) technique known as Transmission Line Pulse (TLP) testing. The silicon implementation of the proposed design passes ±3700V in the Human-Body Model (HBM)."
Development of an optimized LEB filter and its application to INS/GPS test data
(1993) Antonini, Claudio Daniel
"An optimized linear-ellipsoidal-bounded (LEB) filter has been developed and applied to data obtained from a ground test using a combined INS/GPS configuration. In this cascaded configuration, the filter receives eight outputs from the INS (accelerations, velocity, angles, altitude) and six outputs from the GPS (velocities and positions). The GPS measurements have included the effect of selected availability (SA)-of varying or unknown spectrum-which, although likely to be estimated and compensated with some modelling techniques-at the expense of including extra state variables-could also be dealt with using the approach indicated in this article with much less effort. The SA effect is modelled as an unknown-but-bounded (UBB) noise process. Comparisons with an extended Kalman filter (KF) show that KF innovations are not white and the LEB filter innovations are one order of magnitude smaller than those produced by the KF. A simple second order example is developed to show the behavior of the LEB filter when compared to a KF."
Diseño, construcción, simulación 3D y control LPV de un cuadricóptero de forma variante
(2019-11) Ghersin, Alejandro S.; Giribet, Juan I.; Pose, Claudio D.; Mas, Ignacio
"En este trabajo se propone el diseño lineal de parámetros variantes (LPV) para el control de un cuadricóptero cuyos brazos pueden moverse respecto del eje vertical del vehículo, cambiando su forma de acuerdo a requerimientos de misión. El trabajo presenta el desarrollo del simulador multicuerpo y del algoritmo de control junto con una introducción al método LPV, mostrando con su utilización. Además, se presenta una explicación detallada del prototipo construido hasta el momento para las pruebas."
Experimental implementation of an electronic load for global maximum power point tracking
(2016-12) Aliaga, Rodrigo; Muñoz, Javier; Cadena, Fausto; Cossutta, Pablo; Aguirre, Miguel Pablo; Morán, Luis
"This work deals with the partial shading effect in the power curve of a PV solar array. Using a semiconductor device - MOSFET or IGBT - as electronic load added to a buck converter, it is possible to scan the power curve of a photovoltaic string and therefore empirically determine its optimum voltage, even in presence of partial shading. The aim of this paper is to give experimental details regarding the laboratory implementation of a proof-of-concept prototype meant to detect the Global Maximum Power Point. Three cases are presented that consider the partial shading effect of a PV string, with disturbances of different sizes and shapes. In the last part a novel exciting signal is presented, which allows to reduce the scanning time of the power curve. The experimental results illustrate the performance of the implemented circuit."
Fault tolerance analysis of a hexarotor with reconfigurable tilted rotors
(2020) Pose, Claudio D.; Giribet, Juan I.; Mas, Ignacio
"Tilted rotors in multirotor vehicles have shown to be useful for different practical reasons. For instance, increasing yaw maneuverability or enabling full position and attitude control of hexarotor vehicles. It has also been proven that a hexagon-shaped multirotor is capable of complete attitude and altitude control under failures of one of its rotors. However, when a rotor fails, the torque that can be reached in the worstcase direction decreases considerably. This work proposes to actively change the tilt angle of the rotors when a failure occurs. This rotor reconfiguration increases the maximum torque that can be achieved in the most stressful direction, reducing maneuverability limitations. Experimental validations are shown, where the proposed reconfigurable tilted rotor is used in order to control a hexarotor vehicle when a failure appears mid-flight. The impact of the delay in the reconfiguration when a failure occurs is also addressed."
Fault tolerance analysis of a multirotor with 6DOF
(2019-09) Giribet, Juan I.; Pose, Claudio D.; Mas, Ignacio
"Several works have addressed the issue of obtaining a six degree of freedom (6DOF) capable multirotor. However, the capability of keeping full control in the case of a total failure in one of the rotors has not yet been analyzed. In this work, it is proven that eight is the minimum number of rotors necessary to achive 6DOF control of a multirotor, in the case of a total failure in one of them. Also, an octorotor configuration with 6DOF control capabilities in a failure situation is proposed and analyzed through numerical simulations, comparing its flight performance in a nominal and a failure case. "
Fault tolerant control of an hexacopter with a tilted-rotor configuration
(2020) Giribet, Juan I.; Pose, Claudio D.; Mas, Ignacio
"Recientemente, han surgido algunos trabajos reportando las ventajas de volar con multicópteros con rotores inclinados, es decir, rotores que no apunten en la dirección de la vertical del vehículo. En particular, se demostró que para lograr un vehículo hexa-rotor capaz de tolerar fallas en uno de sus rotores es necesario que éstos estén inclinados. Hasta el momento, las validaciones experimentales de estos resultados han considerado fallas parciales en los rotores. Más precisamente, se han analizado casos en los cuales uno de los rotores pierde capacidad de empuje. Sin embargo, los resultados teóricos admiten una falla total de los rotores, es decir, que uno de los rotores se detenga completamente. En este trabajo validamos experimentalmente la falla total de un rotor y mostramos cómo un vehículo hexa-rotor es capaz de mantener su capacidad de maniobra ante la pérdida total de uno de sus rotores."
Fault tolerant control of an hexacopter with a tilted-rotor configuration
(2017) Giribet, Juan I.; Pose, Claudio D.; Mas, Ignacio
"Recently, it was shown that an hexagon-shaped hexa-rotor micro aerial vehicle with unidirectionally spinning tilted rotors is capable of fault tolerant attitude and altitude control. This result has been theoretically proven and validated by simulations. However, experimental results have never been reported yet. In this work experimental results are presented, and a comparison between a tilted-rotor hexacopter with one in a standard rotor configuration is carried out."
Formation control for multi-domain autonomous vehicles based on dual quaternions
(2017-06) Mas, Ignacio; Moreno, Patricio; Giribet, Juan I.; Valentino Barzi, Diego
"Unmanned networked multirobot systems have the potential to accomplish complex field tasks with minimum human intervention. Motion coordination of vehicles that operate in different domains (land, sea, air) is one of the problems that need to be addressed to achieve such a goal. This article presents a representation method based on dual quaternions for leaderfollower formation control architectures. This representation offers the most compact and computationally efficient screw transformation formalism and can be used to describe rigid body motions because they simultaneously describe positions and orientations with only eight parameters. A controller in dual quaternion formation space is proposed and analyzed. Computer simulation results and experimental tests applied to the task of escorting an UGV with UAVs are shown to verify the functionality of the proposed system."
Hexacopter fault tolerant actuator allocation analysis for optimal thrust
(2017) Pose, Claudio D.; Giribet, Juan I.; Ghersin, Alejandro S.
"Recently, it was shown that an hexagon shaped hexarotor vehicle with tilted rotors, is capable of fault tolerant attitude and altitude control. In this work, we propose a strategy to select the signals commanded to each rotor in order to achieve a desired torque and vertical force. The proposed strategy is optimal in the sense that minimizes the maximum force exerted by the rotors. A comparison with the commonly used strategy based upon the Moore-Penrose pseudoinverse is carried out. It is shown that, with the optimal strategy proposed here, maneuverability is improved, because the new method takes into account the actuators constraints. Although the optimal strategy is computationally more demanding than the classical method, the additional computational burden is not significant when both strategies are compared in a real application. To show this, both algorithms were programmed in an autopilot based on an ARM Cortex M3 microcontroller, and the experimental results are presented."
Indoor positioning based on RSSI of WiFi signals: how accurate can it be?
(2019-02-20) Grisales Campeón, Juan Pablo; López, Sebastián; de Jesús Meleán, Sergio R.; Parisi, Daniel; Fierens, Pablo Ignacio; Moldovan, Herman
"There is abundant literature on positioning systems based on WiFi signals. Most of the systems with off-the-shelf hardware use RSSI measurements. In this paper, we try to determine the highest achievable accuracy of such systems. Instead of resorting to a theoretical analysis, e.g., Cram´er-Rao or Ziv-Zakai bounds, we apply state-of-the-art localization algorithms to measurements in a well-controlled experimental setup. We conclude that an accuracy of less than 1 meter seems unrealistic."
Low noise front-end and ADC for real-time ECG System in CMOS process
(2019-03-14) Gardella, Pablo; Villa Fernández, Emanuel; Baez, Eduardo; Biberidis, Nicolás; Cesaretti, Juan Manuel
"This paper presents the design and experimental results of a digital acquisition system based on a chopper-stabilized Instrumentation Amplifier with Common-Mode feedback for CMRR enhancement. Chopping techniques are used to remove both offset and flicker noise, detrimental effects characteristic of pure CMOS processes. A second-order, discrete-time, single-bit Sigma-Delta ADC with CIFB structure is used to convert the signal into the digital domain where it can be processed in real time to diagnose and report urgencies. Measurements on a 0.6μm process have shown that the input CMRR is boosted by 71dB when the feedback is closed through the patient. The input referred integrated noise for the overall system within the ECG band frequencies of 0.1Hz to 400Hz (including the quantization noise) is 4.2μVP, below the recommended maximum detection error of 10.0μVP."
Measurement of the sound-absorption coefficient in situ in eggs cartons using the Tone Burst Method
(2010-06) Quintero-Rincón, Antonio
"A typical solution in an enclosed space, such as a room, is that the reduction in sound level is the results from the installation of eggs cartons materials or fruits cartons materials (for example apple, pear or peach tree). The Tone Burst method is used to measure the sound absorption coefficient of a material at any desired angle of incidence. The goal for this paper is demonstrate that these cartons are a myth when they are used like reducer of the sound level in an enclosed space."
Mimicking spike-timing-dependent plasticity with emulated memristors
(2019-05-07) Cisternas Ferri, Agustín; Rapoport, Alan; Fierens, Pablo Ignacio; Patterson, Germán
"Memristors have found application in neuromorphic circuits and it has been shown that, under certain conditions, they may mimic the behavior of neuronal synapses. Experimenting with memristor-based synapses has several problems. Indeed, memristor samples are difficult to obtain and tweaking their parameters to adapt their behavior requires a long fabrication and testing process. For this reason, simulation and emulation become attractive alternatives for the study of memristive systems. We postulate that emulation has the advantage of working with real-world circuits and not stylized simulation models. In this paper, we propose a basic memristor emulation architecture and show that it can be used to mimic certain characteristics of synapses."

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