Presentaciones a Congresos

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Synthesis of LEB (Linear-ellipsoidal-bounded) regulators and filters for discrete-time systems
(1987) Antonini, Claudio Daniel
"This work is applicable to LTI systems, described by state-variables, whose measurement errors, controls and outputs are to be bounded by upper and lower measurement noises and bounded disturbances. The methodology has been named LEB for its apllication to linear systems, whose variables are contained within Ellipsoidal sets when disturbances and noises are bounded."
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."
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."
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."
Multilevel current source inverter to improve power quality in a distribution network
(2010-07) Aguirre, Miguel Pablo; Calviño, Laura; Corasaniti, V. Fabián; Valla, María Inés
"This paper deals with the problem of reactive power and harmonics in a standard medium voltage (MV) distribution network. It presents the design of a shunt active filter implemented with a multilevel current source inverter (MCSI) connected to the medium voltage level of a power distribution system. The proposed MCSI is made by identical modules where all inductors carry the same amount of current. The current balance is achieved by a Phase-Shifted Carrier SPWM proper implementation. The performance of proposed active filter is thoroughly simulated with Matlab Simulink. It shows very good behavior in steady state and transient conditions."
On the effect of noise and electronics bandwidth on a stochastic-resonance memory device
(2011) Fierens, Pablo Ignacio; Patterson, Germán; Bellomo, Guido; Grosz, Diego
"We recently showed that a ring of two bistable oscillators is capable of storing a single bit of information via stochastic resonance. Memory performance was characterized in terms of the probability of erroneous bit detection and was shown to be minimized for a range of noise intensities. Furthermore, memory persistence was also shown to exhibit a stochastic-resonance behavior. In this paper we investigate the inﬂuence on memory performance, in particular its resilience to noise, on both noise bandwidth and the limited time response of the bistable elements. We show that, for broad ranges of ST and noise bandwidths, the probability of erroneous bit retrieval is also minimized for an optimal noise intensity, exhibiting a deep well as a function of noise intensity. We are interested in the breadth of such a well as it points out to the robustness of the memory device under different working conditions. Moreover, we show that there exists a relation between the noise and ST bandwidths that favors wide wells. We believe that this relation may be of relevance as a design rule for practical memory devices sustained by noise."
Operation of a cryogenic current comparator in presence of mechanical vibrations
(2016-07) Bierzychudek, Marcos E.; Götz, Martin; Schmelzer, Martin
"In measurements with cryogenic current comparators (CCCs), robustness against mechanical distortions is an issue. Sources of distortions are part of the experimental environment, efficient suppression is difficult. In a test setup, we intentionally applied mechanical vibrations to a CCC probe. In the 10 Hz to 3 kHz range, the frequency response of the SQUID detector's output signal was recorded for an integrative and an H ∞ -controller. When applying vibrations at fixed frequency, the stability of the SQUID's locking depended on the chosen controller, but systematic influence on the result of a 12.9 kΩ vs. 100 Ω resistance comparison was not found."
Model predictive control of a current source inverter together with its current source
(2016-10) Cossutta, Pablo; Rivera, Marco; Valla, María Inés; Angélico Engelhardt, Mathias; Aguirre, Miguel Pablo
"Over the past years a great amount of research has been done to interconnect different energy sources with the power grid or different types of loads. Current source inverters have proved to be a good option due to its high reliability, fault tolerant capabilities, quasi soft switching and the use of lower capacitor values among others. Most of the current source inverters topologies have a current source as input, which could be implemented with a buck converter, and they are controlled with cascaded linear control (usually PI controller), rotating frame coordinate transformation and a modulation stage. In this paper a predictive control strategy of a current source inverter together with its associated current source is presented. This strategy allows to track not only the output voltages at the load but also the current source within a single controller. The control algorithm makes use of a discrete time model of the whole system so as to predict its future behaviour for each one of the available switching combinations. Each one of the predicted values are used to minimize a set of predefined control goals within a multiple term cost function that includes cost associated with the commutation frequency and the reference tracking. Simulation results show a good behaviour and fast dynamics with a low switching frequency of all the switches involved. These characteristics make the proposed controller a suitable option to use with high power inverters."
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."
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."
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."
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."
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."
Model predictive control of a multilevel current source inverter together with its current source
(2017-08) Cossutta, Pablo; Angélico Engelhardt, Mathias; Aguirre, Miguel Pablo; Ponce, Juan; Valla, María Inés
"In this paper, a Model Predictive Control (MPC) strategy is applied to a Multilevel Current Source Inverter (MCSI) and its associated current source. The controller uses a discrete-time model of the entire system in order to predict the future behavior for each of the available switch states. The system is composed of a multilevel inverter, a buck converter, an output filter and a load. Each of the calculated values is used to minimize a set of predefined control objectives within a multiterm cost function. It includes costs associated with the switching frequency and reference tracking. This allows to control not only the output voltages of the load, but also the current source and the balance of the internal currents of the inverter. Simulation results show a good performance and fast dynamics with a low switching frequency of all the switches involved. These features make the proposed controller a suitable option for use with high power converters."
Voltage-driven hysteresis model for resistive switching: SPICE modeling and circuit applications
(2017-12) Patterson, Germán; Suñé, Jordi; Miranda, Enrique
"Resistive switching devices are nonlinear electrical components that have drawn great attention in the design of new technologies including memory devices and neuromorphic circuits. In this paper, an SPICE implementation of a novel compact model is presented and put under test by means of different circuit configurations. The model is based on two identical opposite-biased diodes in series with a resistor where the switching behavior is governed by the creation and rupture of multiple conductive channels. Results show that the model is stable under different input sources and amplitudes and, with special interest, in multielement circuits. The model is validated with experimental data available in the literature. Both the corresponding SPICE code and schematic are provided in order to facilitate the model use and assessment."
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."
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."
Vision-based integrated navigation system and optimal allocation in formation flying
(2018-06) Giribet, Juan I.; Mas, Ignacio; Moreno, Patricio
"This article proposes an integrated navigation system for multiple micro aerial vehicles flying in formation. A data fusion algorithm uses measurements from an inertial measurement unit, a GPS receiver, and a camera allowing to use the positioning information of the surrounding vehicles to improve its estimation. A measure of the navigation performance of the formation is defined. Based on such measure, the position where each vehicle should be located in the formation is studied to guarantee the best overall navigation quality."
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."
Predictive control of a 27-level asymmetric multilevel current source inverter
(2018-10) Muñoz, Javier; Soto, Bairon; Villalón, Ariel; Rivera, Marco; Cossutta, Pablo; Aguirre, Miguel Pablo
"In this work a study of a 27-level asymmetric multilevel current source inverter is developed. The presented structure is composed by three current source inverters that together are in a 9:3:1 ratio to produce a current waveform with multiple levels. A model predictive control scheme is developed for tracking the references for the output AC voltages, and to keep the asymmetric ratio between the DC currents even during transient conditions. Furthermore, an extra control goal is included in order to reduce the commutations of the inverter, and therefore reduce the power losses. In order to apply the predictive controller, the equations of the model to be analyzed are obtained systematically for continuous and discrete time domains. Simulations are carried out to validate the proposal and the integrity of the predictive control strategy."

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