Publicaciones

Autores
Gimenez, J.; Herrera, D.; Tosetti, S.; Carelli, R.;

Resumen:
The mapping of partially structured agricultural environments is a valuable resource for precision agriculture. In this paper, a technique for the mapping of a fruit grove by a mobile robot is proposed, which uses only front laser information of the environment and the exact position of the grove corners. This method is based on solving an optimization problem with nonlinear constraints, which reduces errors inherent to the measurement process, ensuring an efficient and precise map construction. The resulting algorithm was tested in a real orchard environment. For this, it is also developed a data filtering method capable to comply efficiently the observation-feature matching. The maximum average error obtained by the methodology in simulations was about 13 cm, and in real experimentation was about 36 cm.

Autores
Gimenez, J. ;Frery, A. ;Flesia, A. ;

Resumen:
The Potts model is frequently used to describe the behavior of image classes, since it allows to incorporate contextual information linking neighboring pixels in a simple way. Its isotropic version has only one real parameter β, known as smoothness parameter or inverse temperature, which regulates the classes map homogeneity. The classes are unavailable and estimating them is central in important image processing procedures as, for instance, image classification. Methods for estimating the classes which stem from a Bayesian approach under the Potts model require to adequately specify a value for β. The estimation of such parameter can be efficiently made solving the pseudo maximum-likelihood (PML) equations in two different schemes, using the prior or the posterior model. Having only radiometric data available, the first scheme needs the computation of an initial segmentation, whereas the second uses both the segmentation and the radiometric data to make the estimation. In this paper, we compare these two PML estimators by computing the mean-square error (MSE), bias, and sensitivity to deviations from the hypothesis of the model. We conclude that the use of extra data does not improve the accuracy of the PML; moreover, under gross deviations from the model, this extra information introduces unpredictable distortions and bias.

Autores
Baumgartner Josef ; Gimenez, J.;Scavuzzo Marcelo ; Pucheta, J.;

Resumen:
Segmentation of multispectral remote sensing images is a key competence for a great variety of applications. Many of the applied segmentation algorithms are generative models based on Markov random fields. These approaches are generally limited to multivariate probability densities such as the normal distribution. In addition, it is usually impossible to adjust the contextual parameters separately for each frequency band. In this letter, we present a new segmentation algorithm that avoids the aforementioned problems and allows the use of any univariate density function as emission probability in each band. The approach consists of three steps: first, calculate feature vectors for every frequency band; second, estimate contextual parameters for every band and apply local smoothing; and third, merge the feature vectors of the frequency bands to obtain final segmentation. This procedure can be iterated; however, experiments show that after the first iteration, most of the pixels are already in their final state. We call our approach successive band merging (SBM). To evaluate the performance of SBM, we segment a Landsat 8 and an AVIRIS image. In both cases, the k̂ coefficients show that SBM outperforms the benchmark algorithms.

Autores
Lopez, N.; Orosco, E.; Perez, E.; Bajinay, S.; Zanetti, R.;

Resumen:
This paper describes a hybrid human-machine interface, based on electro-oculogram (EOG) and electromyogram (EMG), which allows the mouse control of a personal computer using eye movement and the voluntary contraction of any facial muscle. The bioelectrical signals are sensed through adhesives electrodes, and acquired by a custom designed portable and wireless system. The mouse can be moved in any direction, vertical, horizontal and diagonal, by two EOG channels and the EMG signal is used to perform the mouse click action. Blinks are avoided by a decision algorithm and the natural reading of the screen is possible with a specially designed software. A virtual keyboard was used for the experiments with healthy people and with a severely disabled patient. The results demonstrate an intuitive and accessible control, evaluated in terms of performance, time for task execution and user´s acceptance. Besides, a quantitative index to estimate the training impact was computed with good results.

Autores
Orosco, E.; Diez, P.; Mut, V.; Soria, C.;

Resumen:
The electromyographic (EMG) signals are extensively used on feature extraction methods for movement classification purposes. High-Order Statistics (HOS) is being employed increasingly in myoelectric research. HOS techniques could be represented in the frequency domain (high-order spectra, e.g., bispectrum, trispectrum) or in the time domain (higher-order cumulants). More calculus is required for computing the HOS in the frequency domain. On the one hand, classical bispectrum-based features were applied to EMG signals. We propose novel third-order cumulant-based features for EMG signals. Three different classifiers are implemented for muscular-activity detection. Different analysis and evaluations were applied to both HOS-based features in order to qualify and quantify similarities. Based on these results, it is possible to conclude that cumulant-based features and bispectrum-based features had comparable behavior and allowed similar classification rates. Hence, extra calculus in order to convert time- to frequency-domain should be avoided.

Autores
Víctor Hugo Andaluz ; Roberti, F.; Salinas, L.; Toibero, M.; Carelli, R.;

Resumen:
This paper addresses the problem of visual dynamic control based on passivity to solve the target tracking problem of mobile manipulators with eyes-in-hand configuration in the 3D-workspace. The redundancy of the system is used for obstacles avoidance and singular configuration prevention through the system’s manipulability control. The design of the stable control system is based on its passivity properties. A robustness analysis and an L2-gain performance analysis are also presented. Finally, simulation and experimental results are reported to verify the stability and L2-gain performance of the dynamic visual feedback system.

Autores
Leica, P.; Toibero, M.; Roberti, F.; Carelli, R.;

Resumen:
This paper presents a switched control strategy to interpret and design a human-robot bilateral interaction when a human follows a non-holonomic mobile robot at a desired distance while the robot is already following a known path. Furthermore, it proposes and experimentally validates a model that mathematically describes the human behavior when performing the specific task of tracking a mobile robot. This model is useful for the purposes of the control system design and its associated stability analysis. A switched system is proposed to model the complete human-robot behavior. The switching strategy is based on the human-robot relative position and on the human intention to follow the robot. Control errors are defined in terms of human to robot and robot to path instantaneous distances. Stability analyses for the individual controllers, as well as for the complete switching system, are provided by considering Lyapunov theory. Real human-robot interaction experiments show the good performance of the proposed control strategy.

Autores
Alzate, A.; Gomez, L.; Alvarez, H.;

Resumen:
En el diseño simultáneo de proceso se diseña al mismo tiempo el proceso y su sistema de control. En este artículo se presenta una metodología para el diseño simultáneo, basada en los Métodos de Teoría de Conjuntos en Control. En estos métodos además de verificar que la propiedad de controlabilidad se cumpla, es posible cuantificar la controlabilidad y por tanto, complementa el tratamiento clásico para la verificación de la propiedad de controlabilidad. La metodología propuesta se aplica con éxito al conocido problema de referencia (benchmark) del CSTR, y se observa que después de aplicada la metodología, se debe disminuir el volumen del reactor, con el fin de tener un mejor valor del indicador de controlabilidad, que se evidencia en un mejor desempeño del lazo cerrado.

Autores
, V. Andaluz; , P. Canseco; , J. Varela; , J. Ortiz; Roberti, F.; Carelli, R.;

Resumen:
This work presents the kinematic and dynamic modeling of a human-wheelchair system where it is considered that its mass center is not located at the wheels? axis center of the wheelchair. Furthermore, it is presents a new motion controller for human-wheelchair system that is capable of performing positioning and path-following tasks. The proposed controller has the advantage of simultaneously performing the approximation of the robot to the proposed path by the shortest route and limiting its velocity. This controller design is based on two cascaded subsystems: a kinematic controller with command saturation, and a dynamic controller that compensates the dynamics of the robot.

Autores
Amicarelli, A.; , O.; di Sciascio, F.;

Resumen:
This work presents a review of ethanol production from biomass under a process control and states estimation viewpoint. The bacterium Zymomonas mobilis represents an important microorganism used for this purpose but originates high nonlinearities in the fermentation process. Due to the interest in this continuous fermentation process several state estimation and linear as well as nonlinear control tools have been proposed in the last years. It is of great importance the disposition of a procedure with the aim to integrate estimators design and process controllers. Based on an exhaustive literature revision, in this work it is proposed a design procedure for estimators and control strategies for this particular process.

Autores
Orosco, E.; Diez, P.; , E.; Mut, V.; Soria, C.; di Sciascio, F.;

Resumen:
The electromyographic (EMG) signals are extensively used on feature extraction methods for movement classification purposes. High-Order Statistics (HOS) is being employed increasingly in myoelectric research. HOS techniques could be represented in the frequency domain (high-order spectra, e.g., bispectrum, trispectrum) or in the time domain (higher-order cumulants). More calculus is required for computing the HOS in the frequency domain. On the one hand, classical bispectrum-based features were applied to EMG signals. We propose novel third-order cumulant-based features for EMG signals. Three different classifiers are implemented for muscular-activity detection. Different analysis and evaluations were applied to both HOS-based features in order to qualify and quantify similarities. Based on these results, it is possible to conclude that cumulant-based features and bispectrum-based features had comparable behavior and allowed similar classification rates. Hence, extra calculus in order to convert time- to frequency-domain should be avoided.

Autores
Lopez, N.; Orosco, E.; Perez, E.; Bajinay, S.; Zanetti, R.; Valentinuzzi, M.;

Resumen:
This paper describes a hybrid human-machine interface, based on electro-oculogram (EOG) and electromyogram (EMG), which allows the mouse control of a personal computer using eye movement and the voluntary contraction of any facial muscle. The bioelectrical signals are sensed through adhesives electrodes, and acquired by a custom designed portable and wireless system. The mouse can be moved in any direction, vertical, horizontal and diagonal, by two EOG channels and the EMG signal is used to perform the mouse click action. Blinks are avoided by a decision algorithm and the natural reading of the screen is possible with a specially designed software. A virtual keyboard was used for the experiments with healthy people and with a severely disabled patient. The results demonstrate an intuitive and accessible control, evaluated in terms of performance, time for task execution and user´s acceptance. Besides, a quantitative index to estimate the training impact was computed with good results.

Autores
Gimenez, J.; Herrera, D.; Tosetti, S.; Carelli, R.;

Resumen:
The mapping of partially structured agricultural environments is a valuable resource for precision agriculture. In this paper, a technique for the mapping of a fruit grove by a mobile robot is proposed, which uses only front laser information of the environment and the exact position of the grove corners. This method is based on solving an optimization problem with nonlinear constraints, which reduces errors inherent to the measurement process, ensuring an ecient and precise map construction. The resulting algorithm was tested in a real orchard environment. For this, it is also developed a data ltering method capable to comply eciently the observation-feature matching. The maximum average error obtained by the methodology in simulations was about 13cm, and in real experimentation was about 36cm.

Autores
Auat Cheeín, F.; Herrera, D.; Gimenez, J.; Carelli, R.;

Resumen:
Currently, Chile and Argentina experience serious challenges that affect their agricultural productivity. For example, in Chile, the loss of farmable field due to recent earthquakes, and volcanic eruptions as well as the loss of water reserves due to climate changes are affecting the agriculture. Additionally, both countries are facing a same problem: the loss of human labor force. Field workers are migrating from the farm to other fields in the industry which offer them more stable and more profitable jobs (like the mining industry in Chile, or car assembling lines in Argentina). In this adverse scenario, it becomes necessary to introduce and develop agricultural automation and sensing technologies for both primary (harvesting, seeding, fertilizing, spraying) and secondary tasks (grove supervision, weed detection, hauling, mowing). However, fully robotized farms are not yet a possibility since the transition from human labor force dependent farming to autonomous farming needs to be smooth and requires legal regulation not yet in discussion. In this paper, we summarize the state of the art in human-robot interaction in farmable fields, with emphasis in the current constrains associated with flexible automatization of farms in Argentina and Chile. In particular, we introduce the guidelines for designing a humanrobot interaction strategy for harvesting tasks, that could be used for other agricultural tasks.

Autores
Herrera, D.; Tosetti, S.; Carelli, R.;

Resumen:
In the present article, it is presented the modeling and identification of an autonomous vehicle that has been designed for agricultural tasks. With the purpose of defining the best model structure, different models have been presented. Particularly, it is assumed that the lateral and longitudinal dynamics are decoupled dynamics, and based on this assumption these are modeled and identified in an isolated way. Particular emphasis was made in lateral dynamics. The vehicle under study is a quadricycle (ATV) that has been modified and adapted to work in an autonomous way. It has been presented simulation proofs and experimentation with the real vehicle that allows to guarantee the performance of the developed models.

Autores
Toibero, M.; Roberti, F.; Herrera, D.; Amicarelli, A.; Carelli, R.;

Resumen:
Este trabajo presenta el diseño novedoso de un controlador para el seguimiento de caminos de un robot tipo car-like que incorpora la saturación de los actuadores: el ángulo de giro y la velocidad lineal. El diseño se basa en parte en la técnica de espacio nulo cumpliendo un doble objetivo: por un lado una función de potencial repele la selección de acciones de control fuera de un valor máximo permitido para el ángulo de giro; y por otro lado, se controla el seguimiento de un camino pre-establecido a una velocidad deseada menor a una máxima. Se incluyen en este trabajo el análisis de estabilidad del controlador y su verificación experimental para distintas condiciones empleando un tipo Car-Like de laboratorio.

Autores
Herrera, D.; Roberti, F.; Toibero, M.; Carelli, R.;

Resumen:
In human-robot interaction, the incorporation of social rules results to be crucial to guarantee the comfort of the human. This should be attained by means of improving the legibility of the robot motions, because developing soft and smooth motion only, does not guarantee a social acceptable motion. Hence, in this paper a novel fuzzy logic approach is proposed to incorporate social rules in walking events, where the relative positions, orientations, distances and velocities between the robots and the humans are considered. Additionally to verify its performance, its incorporation in a path-following control through social forces is proposed. The simulation results demonstrate that the system is able to overcome many usual interferer situations, and to adapt his behavior to different interference events over time.

Autores
Herrera, D.; Gimenez, J.; Carelli, R.;

Resumen:
This paper proposes a dynamical modelling of a carlike robot based on the port-Hamiltonian approach. It consists in projecting the dynamics of a free body into the possible velocity space determined by the non-holonomic constraints of the vehicle. For this approach, it is considered a simplified bicycle-like representation of the Ackermann mechanism with rear traction and steering control on the front wheel. Simulations are given to illustrate the effectiveness of the approach.

Autores
Herrera, D.; Montesdeoca, J.; Roberti, F.; Toibero, M.; Carelli, R.;

Resumen:
A complete characterization of the behavior in human-robot interaction (HRI) includes both: the behavior dynamic and the control laws that characterize as the behavior is regulated with the perception information. In this way, the present work proposes a leader-follower coordinated control that allows to include special dynamic behaviors between humans. Additionally these have been supported by social rules of proxemics and dynamic models of human-behavior that guarantee more comfortable interactions. For the detection and following of the human, it is used a Kinect sensor on board of a Pioneer 3AT robot (a differential drive robot), which allows the experimental validation of the proposed scheme of control.

Autores
Toibero, M.; Roberti, F.; Herrera, D.; Amicarelli, A.; Carelli, R.;

Resumen:
Este trabajo presenta el diseño novedoso de un controlador para el seguimiento de caminos de un robot tipo car-like que incorpora la saturación de los actuadores: el ángulo de giro y la velocidad lineal. El diseño se basa en parte en la técnica de espacio nulo cumpliendo un doble objetivo: por un lado una función de potencial repele la selección de acciones de control fuera de un valor máximo permitido para el ángulo de giro; y por otro lado, se controla el seguimiento de un camino pre-establecido a una velocidad deseada menor a una máxima. Se incluyen en este trabajo el análisis de estabilidad del controlador y su verificación experimental para distintas condiciones empleando un tipo Car-Like de laboratorio

Autores
Lage, A.; Correa, J.;

Resumen:
En el siguiente trabajo se presenta un sistema meteorológico desarrollado para la protección de cultivos en zonas rurales. El sistema está formado por mini estaciones meteorológicas que son comandadas por una estación central la cual procesa los datos recopilados y en función de estos, genera alarmas, ya sea por la caída de heladas o la aparición de vientos Zonda. El sistema, además de detectar la aparición de vientos Zonda, permite predecir con varias horas de anticipación la formación de posibles heladas, brindándole al agricultor una muy útil herramienta a la hora de tener que combatir este tipo de acontecimientos.

Autores
Alzate, A.; Amicarelli, A.; Gomez, L.; di Sciascio, F.;

Resumen:
This paper proposes a novel Model Predictive Control strategy of dissolved oxygen (DO). The control design finds application on the Bt delta-endotoxins batch process production. This strategy improves the DO control by preventing the usual drawbacks that appear with a step level change in the DO reference profile. Simulations results are provided as well as comparison results against a well-known Lyapunov based controller and a classical PID controller.

Autores
extern321; Amicarelli, A.; Ortiz, O.;extern322; di Sciascio, F.;

Resumen:
Bacillus thuringiensis is a microorganism that allows the biosynthesis of δ-endotoxins with toxic properties against some insect larvae, being often used for the production of biological insecticides. A key issue for the bioprocess design consists in adequately tracking a pre-specified optimal profile of the dissolved oxygen concentration. To this effect, this paper aims at developing a novel control law based on a nonlinear dynamic inversion method. The closed-loop strategy includes an observer based on a Bayesian Regression with Gaussian Process, which is used for on-line estimating the biomass present in the bioreactor. Unlike other approaches, the proposed controller leads to an improved response time with effective disturbance rejection properties, while simultaneously prevents undesired oscillations of the dissolved oxygen concentration. Simulation results based on available experimental data were used to show the effectiveness of the proposal.

Autores
Toibero, M.; Roberti, F.; Herrera, D.; Amicarelli, A.; Carelli, R.;

Resumen:
Este trabajo presenta el diseño novedoso de un controlador para el seguimiento de caminos de un robot tipo car-like que incorpora la saturación de los actuadores: el ángulo de giro y la velocidad lineal. El diseño se basa en parte en la técnica de espacio nulo cumpliendo un doble objetivo: por un lado una función de potencial repele la selección de acciones de control fuera de un valor máximo permitido para el ángulo de giro; y por otro lado, se controla el seguimiento de un camino pre-establecido a una velocidad deseada menor a una máxima. Se incluyen en este trabajo el análisis de estabilidad del controlador y su verificación experimental para distintas condiciones empleando un tipo Car-Like de laboratorio.

Autores
extern323; Amicarelli, A.; Gomez, L.; di Sciascio, F.;

Resumen:
The case of Bacillus thuringiensis process is developed in a batch operation, and its operational conditions are defined according to a phenomenological-based model. Batch processes are inherently irreversible. In fact, design parameters and initial states can affect irreversibility and controllability of a batch process. Current design methodologies do not include controllability as a criterion for process specification. In this work, a novel design methodology is presented using set-theoretic methods and a controllablilty index to find the best design parameter and initial state values. Using this methodology the controllability index is doubled improving the dynamic behavior of the process.

Autores
Alzate, A.; Amicarelli, A.; Gomez, L.; di Sciascio, F.;

Resumen:
This paper proposes a novel Model Predictive Control strategy of dissolved oxygen (DO). The control design finds application on the Bt δ-endotoxins batch process production. This strategy improves the DO control by preventing the usual drawbacks that appear with a step level change in the DO reference profile. Simulations results are provided as well as comparison results against a well known Lyapunov based controller and a classical PID controller.

Autores
Herrera, D.;

Resumen:
Una completa caracterización del comportamiento de interacción humano robot (IHR) incluye dos aspectos: la dinámica de comportamiento, y las leyes de control que caracterizan cómo el comportamiento es regulado con la información de la percepción. De esta manera, este trabajo propone un control coordinado lder-seguidor que permite incorporar comportamientos dinámicos característicos entre humanos, que apoyados de reglas sociales de proxémica, y modelos de dinámica de comportamiento humano garantizan un mayor confort durante este tipo de interacción. Para la identicación y seguimiento del humano se hace uso de un sensor Kinect a bordo de un robot Pioneer 3AT que permite validar experimentalmente el rendimiento del controlador diseñado. Los resultados muestran que incluir dinámicas de comportamiento social en el diseño robótico garantiza su aceptación social y por tanto su inclusión en tareas humanas.

Autores
Herrera, D.;

Resumen:
En la interacción entre humanos y robots, la incorporación de reglas sociales resulta ser crucial para garantizar el confort del humano. Este se consigue al mejorar la legibilidad de los movimientos del robot, ya que efectuar movimientos suaves y amortiguados, no garantiza en la aceptación social. Desde el punto de vista de las decisiones, este trabajo propone un enfoque basado en lógica difusa para incorporar normas sociales de negociación no verbal, usuales entre peatones mientras caminan, donde se consideran las posiciones, orientaciones, distancias y velocidades relativas entre humanos y robots para garantizar una acción estrechamente relacionada a la percepción. Se propone así su incorporación a un control de seguimiento de camino fundamentado en el modelo de fuerzas sociales. Los resultados de la simulación demuestran que el sistema es capaz de superar muchas situaciones habituales de interferencia entre humano y robot, y adaptar dinámicamente su comportamiento.