Grupo de Investigacion Aplicada GIA MDPI

Molina de Aragón, Spain

Grupo de Investigacion Aplicada GIA MDPI

Molina de Aragón, Spain
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Franch J.,Polytechnic University of Catalonia | Rodriguez-Fortun J.M.,Grupo de Investigacion Aplicada GIA MDPI
2009 European Control Conference, ECC 2009 | Year: 2015

This paper proposes a trajectory controller and a trajectory generation algorithm for an Ackerman vehicle. The definition of the system is based on a dynamic model which makes it possible to describe it in terms of the input signals normally reacheable for the driver: the torque of the engine related with the level of the gas pedal, and the movement of the steering wheel. This way, this control method can be implemented on any existing vehicle with minimum changes. For handling the nonlinearities present in the system, the mathematical description of the Ackerman vehicle is arranged in such a way that it fulfills the flatness conditions, making it possible to apply dynamic linearization. Another benefit of the proposed flat description is the close relationship between the flat outputs and the geometrical description of the path, so that the development of the control law for reaching any point in the surroundings of the vehicle is straightforward. In this connection, the trajectory generation algorithm automates a way of defining a trajectory out of a set of intermediate points. The robustness of the system against disturbances is assured by a closed loop control algorithm designed on the flat system. © 2009 EUCA.

Puig L.,University of Zaragoza | Bermudez J.,Grupo de Investigacion Aplicada GIA MDPI | Sturm P.,French Institute for Research in Computer Science and Automation | Guerrero J.J.,University of Zaragoza
Computer Vision and Image Understanding | Year: 2012

Omnidirectional cameras are becoming increasingly popular in computer vision and robotics. Camera calibration is a step before performing any task involving metric scene measurement, required in nearly all robotics tasks. In recent years many different methods to calibrate central omnidirectional cameras have been developed, based on different camera models and often limited to a specific mirror shape. In this paper we review the existing methods designed to calibrate any central omnivision system and analyze their advantages and drawbacks doing a deep comparison using simulated and real data. We choose methods available as OpenSource and which do not require a complex pattern or scene. The evaluation protocol of calibration accuracy also considers 3D metric reconstruction combining omnidirectional images. Comparative results are shown and discussed in detail. © 2011 Elsevier Inc. All rights reserved.

Rodriguez-Fortun J.M.,Grupo de Investigacion Aplicada GIA MDPI | Orus J.,Grupo de Investigacion Aplicada GIA MDPI | Alfonso J.,Grupo de Investigacion Aplicada GIA MDPI | Castellanos J.A.,University of Zaragoza
Proceedings of the 2010 American Control Conference, ACC 2010 | Year: 2010

The ever increasing resolution of metrological and production devices, with required operation ranges below one micron, results in the necessity for isolating the sensor or tool from any external perturbation. For that, it is normally unavoidable the application of active strategies, capable of eliminating the resonance peaks and obtaining good damping results without an important reduction in the stiffness of the system, as it would happen if passive strategies were adopted. Too low stiffness of the system would result in accuracy losses due to large displacements of the device under external perturbations. For the active vibration control strategies at so low displacement ranges, the piezoelectric actuators represent a good option due to both their high movement accuracy and stiffness. Nevertheless, the nonlinear behaviour of these actuators negatively affects the final efficiency of the control strategy if that characteristic is not taken into account. This work proposes a compensator of the nonlinear effects accompanying a vibration control strategy based on the sky-hook control law. The parameters for the compensator can be estimated either off-line or on-line, and in both cases, experimental results show an important improvement with respect to traditional approaches. © 2010 AACC.

Rodriguez-Fortun J.M.,Grupo de Investigacion Aplicada GIA MDPI | Orus J.,Grupo de Investigacion Aplicada GIA MDPI | Alfonso J.,Grupo de Investigacion Aplicada GIA MDPI | Gimeno F.B.,Grupo de Investigacion Aplicada GIA MDPI | Castellanos J.A.,University of Zaragoza
IEEE/ASME Transactions on Mechatronics | Year: 2013

The accuracy and resolution of metrological devices (coordinate measuring machines -CMM-, interferometers, etc.) are greatly affected by their robustness to external vibrations. This is especially important in the case of micrometric and nanometric microscopes, such as atomic force microscopes (AFM). In such cases, active vibration control strategies are frequently used, requiring actuators capable of fast and accurate responses. Piezoelectric actuators meet these requirements but they suffer from two major drawbacks, hysteresis, and rate dependence, which must be taken into consideration in the design of the control strategy. The present work proposes a novel active vibration control strategy using piezoelectric actuators for metrological devices affected by low external loads. The control strategy combines a classical sky-hook feedback with a feedforward control. The effect of hysteresis is minimized by compensating the senstivity variations of the actuator in oscillatory movements. For the design of the feedforward law, the present work demonstrates that a stack piezoelectric actuator working as a damper admits a mathematical description fulfilling differential flatness. It also proposes a formulation of the active vibration damping problem in terms of a trajectory tracking command perfectly fitted to the flatness-based control law. This strategy obtains damping improvements in the entire frequency range of operation without the instability problems derived from high feedback gains. © 1996-2012 IEEE.

Rodriguez-Fortun J.M.,Grupo de Investigacion Aplicada GIA MDPI | Orus J.,Grupo de Investigacion Aplicada GIA MDPI | Alfonso J.,Grupo de Investigacion Aplicada GIA MDPI | Sierra J.R.,Grupo de Investigacion Aplicada GIA MDPI | And 3 more authors.
Mechatronics | Year: 2012

In recent times, the interest from scientific and industrial community for the micrometric range has observed an important growth. The advances in microelectronics or the research on microbiology are just two examples of fields requiring technologies capable of assuring accurate displacements in that range. The present work focuses on the mechanical and control design of a micrometer range positioning and tracking platform using mathematical models. In a first phase, these models permit to identify the relationship between the dynamic performance of the structure and the mechanical properties of the elements that compose it. At the very beginning of the design, this information is used for the development of the different parts of the platform. Afterwards, once an initial design is finished and 3D models are available, the design is refined using finite element tools. In parallel to the mechanical design, the knowledge of the system embodied in the mathematical model is profited in the design of a control strategy for tracking and positioning. The proposed control strategy combines a linear controller based on differential flatness with a hysteresis compensator for correcting this nonlinear effect of the piezoelectric actuators. In the present paper, the mathematical derivation of the system model, its application to the design and validation of the platform and the final closed loop experimental evaluation are described. © 2012 Elsevier Ltd. All rights reserved.

Rodriguez-Fortun J.M.,Grupo de Investigacion Aplicada GIA MDPI | Orus J.,Grupo de Investigacion Aplicada GIA MDPI | Buil F.,Grupo de Investigacion Aplicada GIA MDPI | Castellanos J.A.,University of Zaragoza
Mechatronics | Year: 2010

Piezoelectric actuators are becoming very popular in applications such as nanopositioning, active vibration control or noise reduction, sometimes as part of so called smart structures. The possibility of accurately moving big loads on a micrometric scale and over a wide range of frequencies has resulted in an intense growth of this technology. This interest has prompted the development of a wide variety of mathematical models available for describing their behaviour, whose suitability depends on the specific application involved. This work overcomes this limitation by unifying the different modelization options for stack and stack-based actuators in a general Bond Graph model structure capable of handling the most important physical phenomena observed in these actuators, both linear, such as direct and indirect piezoelectric effects or rate dependence, and nonlinear, such as hysteresis. This model structure represents a basis for specific applications, and can be used for control or simulation purposes thanks to its high generality and adjustment capabilities. The proposed Bond Graph structure graphically shows the power flow between the electrical and mechanical frameworks of the piezoelectric actuator, and uses a modular structure for separately representing the electrical polarization of the material and its macroscopic electrical and mechanical effects. Finally, the model is successfully applied to describe the rate dependent behaviour of the Cedrat Groupe APA-120ML actuator. In this connection, an experimental identification method is described and adapted for implementing hysteresis descriptions based on simple operators or in differential equations in the model structure (O-based and DE-based models). These two typologies cover the majority of the models available, proving the generality of the proposed piezoelectric model for implementing less general or specific phenomenon descriptions into its structure. In consequence, the main contribution of this work is the development of a general framework for modelling piezoelectric actuators, comprising a graphical Bond Graph model and an adjustment procedure, which is flexible enough to embody different representations of the phenomena present in these actuators, and with a modular structure that admits different levels of complexity depending on the phenomena incorporated in the model. © 2010 Elsevier Ltd. All rights reserved.

Seco T.,Grupo de Investigacion Aplicada GIA MDPI | Bermudez J.,Grupo de Investigacion Aplicada GIA MDPI | Paniagua J.,Grupo de Investigacion Aplicada GIA MDPI | Castellanos J.A.,University of Zaragoza
Proceedings - 8th IEEE International Conference on Mobile Ad-hoc and Sensor Systems, MASS 2011 | Year: 2011

Wireless sensor networks (WSNs) have gained an increasing interest in logistic applications. In this paper, we propose a universal hardware and software architecture to measure environmental variables in a dynamic heterogeneous plug-and-play WSN. In this framework the physical structure of the WSN is automatically and transparently generated from the final user. Each node of the WSN communicates through a middle level configurable service-oriented layer. Composition of these services defines high-level virtual instruments for the final user. The proposed WSN is able to configure dynamically these virtual links to achieve the user requirements. The reported strategy is aimed at giving support to collaborative systems, e.g. stock management, intelligent machinery, etc, performing their commanded tasks within indoor environments. To demonstrate the applicability of the proposed method, the paper presents a particular implementation of the described architecture in an intelligent transportation system where both surveillance and control tasks of perishable goods are required. © 2011 IEEE.

Rodriguez-Fortun J.M.,Grupo de Investigacion Aplicada GIA MDPI | Orus J.,Grupo de Investigacion Aplicada GIA MDPI | Alfonso J.,Grupo de Investigacion Aplicada GIA MDPI | Buil F.,Grupo de Investigacion Aplicada GIA MDPI | Castellanos J.A.,University of Zaragoza
IFAC Proceedings Volumes (IFAC-PapersOnline) | Year: 2011

Piezoelectric stack actuators are characterized by their high resolution and precision in micro and nanometric displacements, being capable of very fast responses and reaching bandwidth ranges in the order of kHz. Consequently, these actuators are extensively used both for positioning and active vibration damping in demanding applications such as SPM (Scanning Probe Microscopy), AFM (Atomic Force Microscopy) or manufacturing systems for MEMS (Micro-Electro- Mechanical Systems). However, piezoelectric materials and actuators suffer from two important drawbacks, which have to be taken into account for effectively reaching the highest combination of precision and speed: hysteresis and rate dependence. In this paper, we describe a framework for modeling stack-based piezoelectric actuators using a Bond-Graph representation. The model considers the hysteresis nonlinearity and the rate-dependence, taking into account both direct and inverse piezoelectric effects. Based on this representation, and on the variation of the effective electrical capacitance of the actuator due to the hysteresis phenomenon, a compensation strategy is developed. Experimental results obtained with amplified piezoelectric actuators are introduced for validating the model, the identification strategy and the benefits of the proposed compensation algorithm in comparison with previously reported work in the literature. © 2011 IFAC.

Rodriguez-Fortun J.M.,Grupo de Investigacion Aplicada GIA MDPI | Orus J.,Grupo de Investigacion Aplicada GIA MDPI | Alfonso J.,Grupo de Investigacion Aplicada GIA MDPI | Rotella F.,National Engineering School of Tarbes | Castellanos J.A.,University of Zaragoza
Proceedings of the IEEE Conference on Decision and Control | Year: 2011

Positioning and tracking devices with micrometer range and sub-micrometer resolution are becoming of special interest in recent years for an extending range of applications including metrological devices, manipulators and mechanization systems both in research and high precision industries (for example, semiconductors). The control of these systems is not an easy task because of its normally high stiffness and the coupling existing between the different degrees of freedom. The present work proposes a control strategy based on differential flatness for static positioning and dynamic trajectory tracking with a platform of three degrees of freedom. The system uses piezoelectric actuators and is specially conceived for metrological devices, which do not suffer important external loads. The proposed method permits to decouple the design of a closed loop control for each degree of freedom and calculates an open loop command directly from the trajectory definition in the three degrees of freedom. The performance of the controller has been experimentally checked both in positioning and tracking applications. © 2011 IEEE.

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