Rony Caballero

Methodology for Zero-moment Point Experimental Modeling in the Frequency Domain

Frequency domain methodology is applied to obtain a nominal model for the Zero-Moment Point (ZMP) stability index of a biped robot in an attempt to establish a relationship between the robot trunk trajectories and the stability margin of the contact surface of the foot (or feet) touching the supporting soil. To this end the biped robot trunk is excited with a variable frequency sinusoidal signal around several operating points. These input oscillations generate other output oscillations that can be analyzed with the help of the ZMP measurement system. The proposed ZMP modeling approach not only considers classical rigid body model uncertainties but also non-modelled robot mechanical structure vibration modes. The non-linear ZMP model is obtained following three consecutive stages: Equivalent inverted pendulum dynamics, where saturation and acceleration upper bounds are taken into account, non-modelled inverted pendulum dynamics, including non-linear effects, and low-pass dynamics defining the system cut-off frequency. The effectiveness of this method is demonstrated in practice with the SILO2 biped robot prototype, and a simple control strategy is implemented in order to validate experimentally the usefulness of the models developed.

La Nariz Electrónica: Estado del Arte

This paper presents the artificial olfaction systems or electronic noses state of art , their operation and applications. Moreover, electronic olfaction concept and more representative applications are reviewed. Then the similarities between human olfaction and electronics devices are analyzed. Finally, the main concepts related with the use of electronic noses in autonomous robots and their applications are described.

Robust Cascade Controller for Nonlinearly Actuated Biped Robots: Experimental Evaluation

In this paper we consider the postural stability problem for nonlinearly actuated quasi-static biped robots, both with respect to the joint angular positions and also with reference to the gripping effect between the foot/feet against the ground during robot locomotion. Zero moment point based mathematical models are developed to establish a relationship between the robot state variables and the stability margin of the foot (feet) contact surface and the supporting ground. Then, in correspondence with the developed dynamical model and its associated uncertainty, and in the presence of non-modeled robot mechanical structure vibration modes, we propose a robust control architecture that uses two cascade regulators. The overall robust control system consists of a nonlinear robust variable structure controller in an inner feedback loop for joint trajectory tracking, and an H∞ linear robust regulator in an outer, direct zero moment point feedback loop to ensure the foot-ground contact stability. The effectiveness of this cascade controller is evaluated using a simplified prototype of a nonlinearly actuated biped robot in double support placed on top of a one-degree-of-freedom mobile platform and subjected to external disturbances. The achieved experimental results have revealed that the simplified prototype is successfully stabilized.

Adaptive Filtering for Mobile Robot Localization with Unknown Odometry Statistics

One of the most important tasks in mobile robotics is the vehicle self localization from a reference frame system. In this sense, most of the mobile robots fuse odometry sensors with laser range finders or sonar sensors. Nevertheless, the odometry and kinematic model error statistics are usually unknown and time variant. An Adaptive Extended Kalman Filter is proposed for Mobile Robot Localization and the first and second moment of odometry sensors noise estimation.

A New Stability Index for Metro Lines

In this work a new method to analyze the stability of metro lines with respect to a previously constructed time schedule is presented. For this purpose, metro lines are modelled using a nonlinear real time discrete space state representation and then the Lyapunov-based stability analysis is applied considering time delays of trains as disturbances. As a result a new set of indexes which relate time delays with the validity of the actual time schedule when falling inside a particular ‘stability area’ are defined. Results obtained in a simulated environment show that the new stability indexes are able to evaluate quantitatively and qualitatively the effects of saturation in metro lines as well as predict the need for rescheduling

Dynamic state feedback for zero moment point biped robot stabilization

The aim of this paper is to develop and test experimentally a ZMP direct feedback controller that could handle adequately some limitations presented by other known controllers, specifically lack of robustness due to non-modeled dynamics, saturation effect of non-ideal actuators, and slow response time to disturbances. After ZMP modelling the design of the proposed nonlinear dynamic state feedback controller is presented, where the concept of total stability is employed to ensure biped robot dynamic balance. The controller is applied to a biped robot of 14 degrees of freedom and experimental results are presented.

Detección de Características de Imagen y Flujo Óptico en Espacios Confinados Acuáticos

Resumen– En este trabajo de investigación se compara y evalúa los algoritmos de detección de esquinas basados en el algoritmo de Harris, así como el de Shi-Tomasi. El estudio se realiza en condiciones acuáticas con poca y mucha turbiedad. Posteriormente se presenta y evalúa un algoritmo para el seguimiento de esquinas en espacios confinados acuáticos basado en el flujo óptico. Los resultados obtenidos por el mismo han resultado muy prometedores. Palabras clave—detección de esquinas, flujo óptico, procesamiento de imágenes submarinas.

The R and D activity as a supporting tool for the active teaching and learning methodology in an engineering course

R&D activities as a supporting tool of the active teaching and learning methodologies in an engineering course has been less explored. This document compares the results obtained after two questionnaires were applied to two different groups of students at the College of Electrical Engineering (FIE) at the Universidad Tecnologica de Panama. The first questionnaire was applied to an undergraduate group of Electromechanical Engineering students. The second questionnaire was applied to FIE faculty members. Both questionnaires try to measure the insertion of R&D results in the curricular content of an engineering course while using the active teaching and learning approach.