BUSCADOR RECOLECTA

[EN] Automatic control of robotic systems nowadays deals more and more with the implementation of different tasks to be achieved by the robot with distinct complexity degree, periodic or aperiodic, with local execution or distributed along a communication network and needing to deal with different kinds of hardware. Deal with the controller implementation for a new robotic platform involved to develop suitable software again for the new hardware or, in the best case, to adapt the existing one. In the recent years it has been tending to a component-based programing that allows to develop reusable software and to use a middleware that make it possible to abstract the developed software from the used hardware and from the available communication protocols. At this paper one of these middleware has been used, specially oriented to robotics as is OROCOS. Using the Orocos Toolchain library the real-time components needed for the implementation of several dynamic controllers for a parallel manipulator have been developed. At this paper the robot and the designed controllers are described and the results over the actual robot are shown., [ES] La complejidad actual de los sistemas robotizados y de las aplicaciones que éstos deben realizar requiere que los robots dispongan de un control automático que permita la ejecución de las distintas tareas que forman parte del algoritmo de control y que tenga en cuenta cuestiones relacionadas por ejemplo con la periodicidad, el modo de ejecución, el hardware que se utilizará, etc. Para el desarrollo de este tipo de aplicaciones de control en los últimos añ os se tiende a la programación basada en componentes puesto que ésta permite obtener código reusable. Así mismo también se está incrementando la utilización de middlewares que permiten la abstracción de los sistemas operativos, el soporte de tiempo real y la infraestructura de comunicaciones. En el presente artículo se propone la utilización de un middleware orientado especialmente a la robótica: OROCOS. Así se describe cómo haciendo uso de una de sus librerías, Orocos Toolchain, se han desarrollado una serie de componentes correspondientes a distintos algoritmos para el control dinámico de robots, aplicándose a un robot paralelo de 3 grados de libertad (DOF)., Los autores desean expresar su agradecimiento al Ministerio de Ciencia e Innovacion de Espa ´ na por la financiaci ˜ on´
parcial de este trabajo bajo los proyectos (FEDER/CICYT) de investigacion DPI2009-13830-C02-01 y DPI2010-20814-C02- ´
(01, 02).

This paper presents in detail how to model, identify, and control a 3-DOF prismatics-revolute-spherical parallel manipulator in terms of relevant parameters. A reduced model based on a set of relevant parameters is obtained following a novel approach that considers a simplified dynamic model with a physically feasible set of parameters. The proposed control system is compared with the response of a model-based control that considers the complete identification of the rigid-body dynamic parameters, friction at joints, and the inertia of the actuators. The control systems are implemented on a virtual and an actual prototype. The results show that the control scheme based on the reduced model improves the trajectory tracking precision when comparing with the control scheme based on the complete set of dynamic parameters. Moreover, the reduced model shows a significant reduction in the computational burden, allowing real-time control., This work was supported in part by the Spanish Government under Grant DPI2010-20814-C02-01 (IDEMOV) and in part by the Consejo de Desarrollo Cientifico, Humanistico y Tecnologico de la Universidad de Los Andes (CDCHT-ULA) under Grant I-1286-11-02-B.

The aim of this article is to develop, from the mechatronic point of view, a low-cost parallel manipulator (PM) with 3-degrees of freedom (DOF). The robot has to be able to generate and control one translational motion (heave) and two rotary motions (rolling and pitching). Applications for this kind of parallel manipulator can be found at least in driving-motion simulation and in the biomechanical field. An open control architecture has been developed for this manipulator, which allows implementing and testing different dynamic control schemes for a PM with 3-DOF. Thus, the robot developed can be used as a test bench where control schemes can be tested. In this article, several control schemes are proposed and the tracking control responses are compared. The schemes considered are based on passivity-based control and inverse dynamic control. The control algorithm considers point-to-point control or tracking control. When the controller considers the system dynamics, an identified model has been used. The control schemes have been tested on a virtual robot and on the actual prototype. © 2012 Taylor & Francis Group, LLC., The authors wish to express their gratitude to the Plan Nacional de I+D, Comision Interministerial de Ciencia y Tecnologia (FEDER-CICYT) for the partial financing of this study under the projects DPI2009-13830-C02-01 and DPI2010-20814-C02-(01, 02). This work was also supported in part by the CDCHT-ULA Grant I-1286-11-02-B.

This paper has been possible thanks to the funding of Science and Innovation Ministry of the Spain Government by means of the Researching and Technologic Development Project DPI2010-20814-C02-01 (IDEMOV).

This paper presents a mathematical model for the propagation of errors in body segment kinematics to the location of the center of rotation. Three functional calibration techniques, usually employed for the gleno-humeral joint, are studied: the methods based on the pivot of the instantaneous helical axis (PIHA) or the finite helical axis (PFHA), and the ¿symmetrical center of rotation estimation¿ (SCoRE). A procedure for correcting the effect of soft tissue artifacts is also proposed, based on the equations of those techniques and a model of the artifact, like the one that can be obtained by double calibration. An experiment with a mechanical analog was performed to validate the procedure and compare the performance of each technique. The raw error (between 57 and 68 mm) was reduced by a proportion of between 1:6 and less than 1:15, depending on the artifact model and the mathematical method. The best corrections were obtained by the SCoRE method. Some recommendations about the experimental setup for functional calibration techniques and the choice of a mathematical method are derived from theoretical considerations about the formulas and the results of the experiment., This work has been funded by the Spanish Government (Grants DPI2009-13830-C02-01, DPI2009-13830-C02-02, DPI2010-20814-C02-01, and DPI2010-20814-C02-02).

This paper proposed a new methodology to solve collision free path planning problem for industrial robot using genetic algorithms. The method poses an optimization problem that aims to minimize the significant points traveling distance of the robot. The behavior of more two operational parameters - the end effector traveling distance and computational time - are analyzed. This algorithm is able to obtain the solution for any industrial robot working in the complex environments, just it needs to choose a suitable significant points for that robot. An application example has been illustrated using robot Puma 560. © 2012 Copyright Taylor & Francis and The Robotics Society of Japan., This paper has been made possible by the funding from the Spanish Ministry of MINISTERIO DE CIENCIA E INNOVACION through the Project Research and Technological Development DPI2010-20814-C02-01.

[EN] Purpose - The purpose of this paper is to analyze the impact of the torque, power, jerk and energy consumed constraints on the generation of minimum time collision-free trajectories for industrial robots in a complex environment. Design/methodology/approach - An algorithm is presented in which the trajectory is generated under real working constraints (specifically torque, power, jerk and energy consumed). It also takes into account the presence of obstacles (to avoid collisions) and the dynamics of the robotic system. The method solves an optimization problem to find the minimum time trajectory to perform the tasks the robot should do. Findings - Important conclusions have been reached when solving the trajectory planning problem related to the value of the torque, power, jerk and energy consumed and the relationship between them, therefore enabling the user to choose the most efficient way of working depending on which parameter he is most interested in optimizing. From the examples solved the authors have found the relationship between the maximum and minimum values of the parameters studied. Research limitations/implications - This new approach tries to model the real behaviour of the actuators in order to be able to upgrade the trajectory quality, so a lot of work has to be done in this field. Practical implications - The algorithm solves the trajectory planning problem for any industrial robot and the real characteristics of the actuators are taken into account, which is essential to improve the performance of it. Originality/value - This new tool enables the performance of the robot to be improved by combining adequately the values of the mentioned parameters (torque, power, jerk and consumed energy)., This paper has been made possible thanks to support from the Spanish Ministry of Science and Innovation, through the Project for Research and Technological Development, ref. DPI2010-20 814-C02-01.

[EN] In this paper an analysis of productivity will be carried out from the resolution of the problem of trajectory planning of
industrial robots. The analysis entails economic considerations, thus overcoming some limitations of the existing literature. Two
methodologies based on optimization-simulation procedures are compared to calculate the time needed to perform an industrial
robot task. The simulation methodology relies on the use of robotics and automation software called GRASP. The optimization
methodology developed in this work is based on the kinematics and the dynamics of industrial robots. It allows us to pose a
multiobjective optimization problem to assess the trade-offs between the economic variables by means of the Pareto fronts. The
comparison is carried out for different examples and from a multidisciplinary point of view, thus, to determine the impact of
using each method. Results have shown the opportunity costs of non using the methodology with optimized time trajectories.
Furthermore, it allows companies to stay competitive because of the quick adaptation to rapidly changing markets., This paper has been possible due to the funding from the Science and Innovation Ministry of the Spanish Government by means of the Researching and Technologic Development Project DPI2010-20814-C02-01 (IDEMOV).

[EN] This paper proposes a variation of the instantaneous helical pivot technique for locating centers of
rotation. The point of optimal kinematic error (POKE), which minimizes the velocity at the center of
rotation, may be obtained by just adding a weighting factor equal to the square of angular velocity in
Woltring's equation of the pivot of instantaneous helical axes (PIHA). Calculations are simplified with
respect to the original method, since it is not necessary to make explicit calculations of the helical axis,
and the effect of accidental errors is reduced. The improved performance of this method was validated by
simulations based on a functional calibration task for the gleno-humeral joint center. Noisy data caused a systematic dislocation of the calculated center of rotation towards the center of the arm marker cluster. This error in PIHA could even exceed the effect of soft tissue artifacts associated to small and medium deformations, but it was successfully reduced by the POKE estimation., This work has been funded by the Spanish Government (Grants DPI2009-13830-C02-01, DPI2009-13830-CO2-02, DPI2010-20814-CO2-01, DPI2010-20814-CO2-02).

[EN] The identification of dynamic parameters in low-mobility mechanical systems is addressed and applied to short long arm (SLA) front car suspension. The main goal of the identification technique is to obtain, from experimental measurements, the values of those dynamic parameters (masses, location of the centre of masses, terms of the inertial matrix of the links, constant friction terms and elastic and viscous damping constant terms) that affect the dynamic behaviour of the system. Moreover, additional but important information that could be obtained from the procedure is related to the weight of those terms inside the dynamics of the system, so that simplified dynamic models based on relevant and well-identified parameters can be established. First, a systematic procedure will be presented for obtaining the equations of motion in a linear form with regard to the dynamic parameters to be identified. The main drawbacks related to the identification of parameters in low-mobility mechanisms will be pointed out, mainly the difficulty of determining a natural cutoff point into the singular values of the observation matrix which allows us to determine the true dimension of the set of base parameters and of obtaining an observation matrix well conditioned from the numerical point of view that allows an identification in the presence of measurement error. The procedure proposed for overcoming these problems will be based on the development of symbolic relationships among the physical parameters in order to determine the true rank of the observation matrix and on the consideration of a reduced subset of the base parameters set. These relevant parameters will be selected according to their influence on the dynamic behaviour of the mechanical system. A virtual benchmark will be used for testing purposes. The dynamic models based on relevant parameters show a better adjustment than the complete ones, mainly when the level of noise in the measurements used in the identification process increases., This paper has been possible owing to the funding from the Science and Innovation Ministry of the Spanish Government by means of the Research and Technological Development Project DPI2010-20814-C02-01 (IDEMOV).

This study presents a methodology to tackle robot tasks in a cost-efficientway. It poses amulti-objective optimization
problemfor trajectory planning of robotic arms that an efficient algorithmwill solve. Themethod finds the
minimum time to perform robot tasks while considering the physical constraints of the real working problem
and the economic issues participating in the process. This process also considers robotic system dynamics and
the presence of obstacles to avoid collisions. It generates an entire set of equally optimal solutions for each process,
the Pareto-optimal frontiers. They provide information about the trade-offs between the different decision
variables of the multi-objective optimization problem. This procedure can help managers in decision-making
processes regarding performing tasks, items to be manufactured or robotic services performed to meet with
the current demand, and also, to define an efficient scheduling. It improves productivity and allows firms to
stay competitive in rapid changing markets., The authors thank the funding of Science and Innovation Ministry of the Spain Government by means of the Researching and Technologic Development Project DPI2010-20814-C02-01 (IDEMOV).

[EN] This paper presents a new genetic algorithm methodology to obtain a smooth trajectory planning for industrial robots in complex environments. This method aims to gradually create the collision free trajectory as the robot moves. The presented method deals with the uncertainties associated with the unknown of the kinematic properties of intermediate via points since they are generated as the algorithm evolves towards the solution. As well, the objective of this algorithm is to minimize the trajectory time, which guide the robot motion. As an application example, this algorithm is applied over robot Puma 560. Some numerical examples are provided in this paper to evaluate the functionality of the algorithm., This paper has been possible thanks to the funding of Spanish Education, Culture and Sport Ministry by means of the Researching and Technologi Development Project IDEMOV DPI2010-20814-C02-01

[EN] A new and simple symbolic/geometric procedure to obtain the base inertial parameters of general mechanisms is presented. The procedure is based on: 1) the concept of low mobility of bodies with respect to the Inertial Reference frame (IR), which allows one to determine the inertial parameters that do not have an effect on the motion dynamics; and 2) a generalisation of the mass transfer method introduced in [1,2] in such a way that first and second moments of inertia can also be transferred. The concepts of monopole, dipole and quadrupole mass distributions (multipoles) are introduced as means to visualise the inertia transfers and cancellations geometrically, greatly simplifying the application of the method. Criteria that simplify the symbolic expressions of base inertial parameters and of the equations of motion are given for the selection of optimal frames to define inertial properties. The proposed method is illustrated with a 3RPS parallel manipulator, demonstrating how expressions for the base parameters can be obtained in symbolic form., This research has been partially supported by the Spanish Government grant # DPI2010-20814-C02-01(IDEMOV) and the "Salvador de Madariaga" fellowship #PR2009-0259.