Entity

Time filter

Source Type

Molina de Aragón, Spain

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. Source


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. Source


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. Source


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. Source


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. Source

Discover hidden collaborations