Publications

Flatness‐based disturbance observer for exoskeleton robots under time‐delayed contact forces

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.

A Nonlinear Optimal Control Approach for a Lower-Limb Robotic Exoskeleton

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.

Diseño de un modelo de indicadores de competencias TIC en la docencia universitaria

El objetivo de este trabajo es presentar el diseno de un modelo de indicadores de las competencias en las Tecnologias de la Informacion y la Comunicacion [TIC] en la docencia universitaria. La referencia y fundamentacion para la elaboracion de este modelo ha sido a partir de la revision realizada sobre los indicadores de competencias digitales existentes. La implementacion del modelo nos permite la incorporacion de las TIC en la docencia universitaria y reconducir los procesos de ensenanza-aprendizaje ante las demandas que provienen del Espacio Europeo de Educacion Superior

Coordinación transversal de asignaturas de control y robótica en asignaturas del Máster Universitario en Automática y Robótica

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.

<title>Product disassembly scheduling using graph models</title>

Disassembly problem is a current issue for industrial companies. Governments of different countries promote research in this field. This paper presents the following points. First a brief state of the art in disassembly planning. Next it exposes a solution for the disassembly problem of industrial products. It uses a combination between direct and indirect graph representation for the product, all components that have physical entity are considered as vertices of the graph. Edges of the graph represent the relationships between vertices. There are three different types of edges. First corresponds with accessibility and fastener restrictions. Second corresponds with direct relations between components without fasteners. Last one corresponds with contact relationships, which represent an indifferent choice of the vertices. Based on that representation the paper exposed a method to find the best sequence to disassemble a component. Costs of disassembling each component and of changing tool between each pair of vertices and different sequences of the disassembly are taken into consideration. This method consists in a function minimization defined in the graph domain. In the last point of the paper this method is tested with a remote control disassembly. This method gives a solution to the problem, if several solutions, with the same cost, exist then it gives all of them, and any one of these disassemble sequences could be used to achieve to the target component.

Practical experiences using RobUALab.ejs: a virtual and remote laboratory for Robotics e-learning

Intelligent Robotic Multisensorial System to Build Metallic Structures

Flatness-Based Control in Successive Loops of an H-Type Gantry Crane with Dual PMLSM

A Flexible Java Class Library for Simulating and Teleoperating Robots

El laboratorio virtual como herramienta en el proceso enseñanza-aprendizaje

Deseamos agradecer al Instituto de Ciencias de la Educacion (ICE) de la Universidad de Alicante la financiacion del proyecto educacional: “Red Docente: laboratorios virtuales remotos para el aprendizaje practico de asignaturas de ingenieria II” en la convocatoria 2002/2003.

VISUAL : herramienta para la enseñanza práctica de la visión artificial

Resumen – En este articulo se presenta un enfoque practico para la ensenanza de la vision artificial en la asignatura de “Robots y Sistemas Sensoriales” impartida por el area de Ingenieria de Sistemas y Automatica en la Universidad de Alicante. En primer lugar, se describe la herramienta VISUAL que ha sido desarrollada por miembros del grupo de Automatico, Robotica y Vision Artificial y que permite al alumno especificar un algoritmo de procesamiento de imagenes mediante un esquema grafico formado por un conjunto de diferentes modulos basicos de procesamiento. Asi, la herramienta VISUAL proporciona un interfaz para la vision artificial de manejo intuitivo, al mismo tiempo que permite desarrollos de algoritmos facilmente comprensibles gracias a su escalabilidad y modularidad, posibilitando realizar etapas de procesamiento claramente definidas. Ademas, se comentan algunos de los experimentos practicos propuestos y desarrollados haciendo uso de VISUAL y destinados al reconocimiento y localizacion de objetos para su posterior manipulacion con un robot.

Automatic PC disassembly for component recovery

COOPER (COupled OPEration Robot): control de una estructura articular RRR acoplada a un manipulador

Pendiente de publicacion en las actas de las XXXII Jornadas de Automatica, Sevilla, 7-9 septiembre 2011.

Direct visual servoing framework based on optimal control for redundant joint structures

Data fusion from multiple cameras for automatic disassembly

This study was partly funded by the following Spanish CICYT project “Sistema Robotizado de Desensamblado Automatico basado en Modelos y Vision Artificial” (TAP1999-0436).

Direct visual servo control of a robot to track trajectories in supervision tasks

This paper describes the modelling, simulation and visual servo control of a robot-arm designed for supervision of complex task environments. This robot (mini-robot) has 2 degrees of freedom (hereafter d.o.f.) and it is attached at the end of another anthropomorphic robot with 7 d.o.f. (main robot). In order to achieve a suitable supervision, the mini-robot has to perform a given trajectory around the workspace where the task is developed. With the purpose of obtaining an accurate and fast supervision, this paper presents a novel tracking method carried out in the image space using direct visual servo control.

DEVELOPMENT OF HYBRID LABORATORIES OF INDUSTRIAL SYSTEMS FOR INTERACTIVE LEARNING OF AUTOMATION AND CONTROL

DEVELOPMENT OF HYBRID LABORATORIES OF INDUSTRIAL SYSTEMS FOR INTERACTIVE LEARNING OF AUTOMATION AND CONTROL

Flatness-based control in successive loops for dual-arm robotic manipulators