233 publications from this institution
Abstract This article presents an interactive Java software platform which enables any user to easily create advanced virtual laboratories (VLs) for Robotics. This novel tool provides both support for developing applications with full 3D interactive graphical interface and a complete functional framework for modelling and simulation of arbitrary serial‐link manipulators. In addition, its software architecture contains a high number of functionalities included as high‐level tools, with the advantage of allowing any user to easily develop complex interactive robotic simulations with a minimum of programming. In order to show the features of the platform, the article describes, step‐by‐step, the implementation methodology of a complete VL for Robotics education using the presented approach. Finally, some educational results about the experience of implementing this approach are reported. © 2011 Wiley Periodicals, Inc. Comput Appl Eng Educ 21:E14–E30, 2013
Abstract The article proposes flatness‐based control and a Kalman filter‐based disturbance observer for solving the control problem of a robotic exoskeleton under time‐delayed exogenous disturbances. A two‐link lower‐limb robotic exoskeleton is used as a case study. It is proven that this robotic system is differentially flat. The robot is considered to be subject to unknown contact forces at its free‐end which in turn generate unknown disturbance torques at its joints. It is shown that the dynamic model of the robotic exoskeleton can be transformed into the input–output linearized form and equivalently into the linear canonical Brunovsky form. This linearized description of the exoskeleton's dynamics is both controllable and observable. It allows for designing a stabilizing feedback controller with the use of the pole‐placement (eigenvalues assignment) method. Moreover, it allows for solving the state estimation problem with the use of Kalman Filtering (the use of the Kalman filter on the flatness‐based linearized model of nonlinear dynamical systems is also known as derivative‐free nonlinear Kalman filtering). Furthermore, (i) by extending the state vector of the exoskeleton after considering as additional state variables the additive disturbance torques which affect its joints and (ii) by redesigning the Kalman filter as a disturbance observer, one can achieve the real‐time estimation of the perturbations that affect this robotic system. Finally, by including in the controller of the exoskeleton additional terms that compensate for the estimated disturbance torques, the perturbations' effects can be eliminated and the precise tracking of reference trajectories by the joints of this robot can be ensured.
The use of robotic limb exoskeletons is growing fast either for rehabilitation purposes or in an aim to enhance human ability for lifting heavy objects or for walking for long distances without fatigue. The paper proposes a nonlinear optimal control approach for a lower-limb robotic exoskeleton. The method has been successfully tested so far on the control problem of several types of robotic manipulators and this paper shows that it can also provide an optimal solution to the control problem of limb robotic exoskeletons. To implement this control scheme, the state-space model of the lower-limb robotic exoskeleton undergoes first approximate linearization around a temporary operating point, through first-order Taylor series expansion and through the computation of the associated Jacobian matrices. To select the feedback gains of the H-infinity controller an algebraic Riccati equation is solved at each time-step of the control method. The global stability properties of the control loop are proven through Lyapunov analysis. Finally, to implement state estimation-based feedback control, the H-infinity Kalman Filter is used as a robust state estimator.
En la presente memoria se describe la red docente creada con el objetivo de llevar a cabo la coordinacion docente entre distintas asignaturas del Master Universitario en Automatica y Robotica de la Universidad de Alicante. Se han creado grupos de trabajo con el proposito de coordinar la docencia teorico/practica de asignaturas de dicho Master para dar continuidad en la materia impartida. En concreto, se ha coordinado la docencia de las asignaturas relacionadas con distintos ambitos de las materias de robotica y sistemas de control automatico. Se han disenado tambien trabajos practicos y proyectos coordinados entre las distintas asignaturas empleando laboratorios virtuales desarrollados por el profesorado del Master. A lo largo de la presente memoria se presentan los principales resultados obtenidos, guias docentes elaboradas, asi como el procedimiento para su elaboracion y las dificultades encontradas.
A new approach for fusing visual and force information is shown. First, a new method for tracking trajectories, called movement flow-based visual servoing system, which presents the correct behavior in the image and in the three-dimensional space, is described. The information obtained from this system is fused with that obtained from a force control system in unstructured environments. To do so, a new method of recognizing the contact surface and a system for fusing visual and force information are described. The latter method employs variable weights for each sensor system, depending on a criteria based on the detection of changes in the interaction forces processed by a Kalman filter.
The disassembly of products for they reuse is an important field of research. One aspect that appears when a product is been disassembled is the uncertainty in the trajectories for the removal of a component from the rest of the product. In order to reduce this lack of information, a multi-sensorial system is proposed. This system uses visual and force-sensor information to avoid the unknown factors in the disassembly plan and correct the trajectories generated which are based on the model of the product. This paper also describes the structure of a de-manufacturing system that can perform the desired disassembly task.
Comunicacion presentada en las XXIX Jornadas de Automatica, Tarragona, 3-5 Septiembre 2008.
This paper proposes an image-based visual-servoing algorithm that allows for optimal formation control. The proposed distributed controller utilizes visual features of other team members, retrieved from images captured by onboard cameras, to autonomously plan and perform formation acquisition, keeping or reconfiguration maneuvers. The problems of minimization of the control effort is analyzed and the paper proposes an optimal framework for developing controllers that address the issue. The viability of such a technique is explored through numerical simulations.
