Controlador LQR y SMC Aplicado a Plataformas Pendulares

Una plataforma pendular es una estructura robótica comúnmente empleada en el diseño de controladores dada su dinámica no lineal; este trabajo presenta el modelamiento, diseño e implementación de un controlador óptimo LQR y un controlador en modo deslizante SMC aplicado a dos plataformas comerciales, el péndulo rotatorio invertido de Quanser (RotPen) y el péndulo móvil de Lego (NxtWay). El aporte de este trabajo es presentar una metodología de implementación de controladores sobre plataformas pendulares, atendiendo las respectivas restricciones de hardware y software en prototipos comerciales. El artículo presenta el comportamiento de los controladores diseñados sobre el modelo analítico comparado con su implementación real

Spatiotemporal incidence of Zika and associated environmental drivers for the 2015-2016 epidemic in Colombia

Despite a long history of mosquito-borne virus epidemics in the Americas, the impact of the Zika virus (ZIKV) epidemic of 2015–2016 was unexpected. The need for scientifically informed decision-making is driving research to understand the emergence and spread of ZIKV. To support that research, we assembled a data set of key covariates for modeling ZIKV transmission dynamics in Colombia, where ZIKV transmission was widespread and the government made incidence data publically available. On a weekly basis between January 1, 2014 and October 1, 2016 at three administrative levels, we collated spatiotemporal Zika incidence data, nine environmental variables, and demographic data into a single downloadable database. These new datasets and those we identified, processed, and assembled at comparable spatial and temporal resolutions will save future researchers considerable time and effort in performing these data processing steps, enabling them to focus instead on extracting epidemiological insights from this important data set. Similar approaches could prove useful for filling data gaps to enable epidemiological analyses of future disease emergence events

Contestations Over Indigenous Participation in Bolivia's Extractive Industry: Ideology, Practices, and Legal Norms

The participatory rights of indigenous peoples have been at the center of conflicts over resource extraction, which have recently increased in number and intensity across Latin America. Using comprehensive empirical data about the Guaraníes' participation in Bolivia's gas sector, this study finds that competing claims regarding territory, property, participation, and decision making provide important explanations for contestations over consultation practices and legal norms in the country. It argues that the main conflicts can be explained by (1) the Bolivian state's focus on directly affected communities and those with formally recognized land titles, something that clashes with the Guaraníes' principle of "territorial integrity"; (2) the state's conviction that it holds a monopoly over subsoil resources, and the limited rights to participation that it is willing to grant as a consequence, which the Guaraníes reject; and (3) the dissonance between state customs and regulations and Guaraní uses and customs

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Collision Detector for Industrial Robot Manipulators

The increasingly complex tasks require an enormous effort in path planning within dynamic environments. This paper presents a efficient method for detecting collisions between a robot and its environment in order to prevent dangerous maneuvers. Our methods is based upon the transformation of each robot link and the environment in a set of bounding boxes. The aim of this kind of prismatic approximation is to detect a collision between objects in the workspace by testing collision between boxes from different objects. The computational cost of this approach has been tested in simulations, thus we have set up our environment with a HP20D robot and an obstacle, both represented by their corresponding chain of bounding boxes. The experiment implies to move the robot from an initial position, on the right of the obstacle, to a final position, on the left side of the obstacle, along a straight-line trajectory. The probe enabled us to check the correct behavior of a collision detector in a real situation

LQR and SMC control applied to pendular platforms

A pendular platform is a robotic structure commonly used in the design of controllers given its nonlinear dynamics; This work presents the modeling, design and implementation of an optimal LQR controller and a Sliding Mode SMC controller applied to two commercial platforms, the Quanser rotary inverted pendulum (RotPen) and the Lego mobile inverted pendulum (NxtWay). The contribution of this work is to present a methodology of implementation of LQR and SMC controllers on pendular platforms, attending the respective restrictions of hardware and software in commercial prototypes. The article presents the behavior of the controller designed on the analytical model compared to its implementation

Simulator for Planning Collision-Free Trajectories in Manipulation of Objects Applications

This article presents the functional description of a simulator that plans trajectories in an automatic fashion in order for a Motoman HP20D industrial robot to move box-like objects from an initial to a final position avoiding obstacles in its workspace. The simulator sets up robot positioning based on the data entered by the user as well as the position of obstacles (boxes) by using an offline workspace reconstruction based on a computer vision tool, the main component of which is an RGB-D camera. The vision system estimates the position, orientation and size of a set of boxes to create a virtual representation in the simulator. In addition to that, a collision detection module, cost-efficient in computational terms, is described as the structural block of the trajectory planning process. Finally, the work space road map is obtained through a lazy PRM algorithm, as a global planner, and a type-A* search algorithm, as a local planner. This way, a collision-free trajectory is obtained and animated in the simulator as the final result of the general planning process

3D Object Pose Estimation for Robotic Packing Applications

Given the growth of internet-based trading on a global level, there are several expected logistic challenges regarding the optimal transportation of large volumes of merchandise. With this in mind, the application of technologies such as computer vision and industrial robotics in facing these challenges presents significant advantages regarding the speed and reliability with which palletization tasks, a critical point in the merchandise transportation chain, can be performed. This paper presents a computer vision strategy for the localization and recognition of boxes in the context of a palletization process carried out by a robotic manipulator. The system operates using a Kinect 2.0 depth camera to capture a scene and processing the resulting point cloud. Obtained results permit the simultaneous recognition of up to 15 boxes, their position in space and their size characteristics within the workspace of the robot, with an average error of approximately 3 cm