Abstract Mechatronic systems with nonlinear dynamics are met in motion transmission applications for vehicles and robots. In this article, the control problem for the nonlinear dynamics of mechatronic motion transmission systems is solved with the use of a flatness‐based control approach which is implemented in successive loops. The state‐space model of these systems is separated into a series of subsystems, which are connected between them in cascading loops. Each one of these subsystems can be viewed independently as a differentially flat system, and control about it can be performed with inversion of its dynamics as in the case of input–output linearized flat systems. In this chain of subsystems, the state variables of the subsequent ( )‐th subsystem become virtual control inputs for the preceding ‐th subsystem and so on. In turn, exogenous control inputs are applied to the last subsystem and are computed by tracing backwards the virtual control inputs of the preceding subsystems. The whole control method is implemented in successive loops, and its global stability properties are also proven through Lyapunov stability analysis. The validity of the control method is confirmed in the following two case studies: (a) control of a permanent magnet linear synchronous motor (PMLSM)‐actuated vehicle's clutch and (ii) control of a multi‐Degrees of Freedom (multi‐DOF) flexible joint robot.
University of Alicante and the I.C.E. (Education Sciences Institute), under the educational project: “Educational network: Remote virtual laboratories for the practical learning of engineering subjects”
Este trabajo presenta el diseno, construccion y programacion de un robot modular para el desarrollo tanto de competencias genericas como especificas, en las ensenanzas de electronica, control y programacion del Master de Automatica y Robotica de la Escuela Politecnica Superior de la Universidad de Alicante. En este trabajo se exponen los diferentes modulos propuestos, asi como los objetivos de aprendizaje para cada uno de ellos. Uno de los factores mas importantes a destacar en el presente estudio es el posible desarrollo de la creatividad y el aprendizaje autonomo. Para ello, se desarrollara especialmente un modulo de comunicacion por bluetooth que servira para monitorizar, cambiar y adaptar on-line diversos parametros de control y potencia del robot. Ademas, dicha herramienta se ha introducido como parte de la metodologia en las asignaturas del Master de Electromecanica y Sistemas de Control Automatico. En esta memoria se mostraran los distintos resultados obtenidos durante y en la finalizacion de este trabajo
This paper presents a direct image-based controller to perform the guidance of a mobile manipulator using image-based control. An eye-in-hand camera is employed to perform the guidance of a mobile differential platform with a seven degrees-of-freedom robot arm. The presented approach is based on an optimal control framework and it is employed to control mobile manipulators during the tracking of image trajectories taking into account robot dynamics. The direct approach allows us to take both the manipulator and base dynamics into account. The proposed image-based controllers consider the optimization of the motor signals sent to the mobile manipulator during the tracking of image trajectories by minimizing the control force and torque. As the results show, the proposed direct visual servoing system uses the eye-in-hand camera images for concurrently controlling both the base platform and robot arm. The use of the optimal framework allows us to derive different visual controllers with different dynamical behaviors during the tracking of image trajectories.
Comunicacion presentada en el 11th International Conference on Advanced Robotics, June 30-July 3, 2003, University of Coimbra, Portugal
<title>Abstract</title> The article proposes a nonlinear optimal control method for the dynamic model of the parallel double inverted pendulum. Three different forms of this system are considered: (i) two poles mounted on the same cart resulting into a model with four state variables and one control input, (ii) two poles mounted on the same cart resulting into a model with six state variables and one control input, (iii) two different cart-pole systems connected through an elastic link, resulting into a model with eight state variables and two control inputs. To implement the proposed nonlinear optimal control method the dynamic model of the parallel double pendulum undergoes approximate linearization around a temporary operating point which is updated at each sampling instance. This operating point is defined within each sampling period by the present value of the state vector of the parallel double inverted pendulum and by the last sampled value of the control inputs vector. The linearization process is based on first-order Taylor series expansion and on the computation of the associated Jacobian matrices. For the approximately linearized model of the parallel double inverted pendulum a stabilizing H-infinity feedback controller is designed. To compute the feedback gains of this controller an algebraic Riccati equation is also being solved at each time-step of the control algorithm. The global stability properties of the control scheme are proven through Lyapunov analysis. First it is demonstrated that the H-infinity tracking performance criterion holds, which signifies robustness of the control method under model uncertainty and external perturbations. Moreover, under moderate conditions it is proven that the control loop of the parallel double inverted pendulum is globally asymptotically stable. To implement state estimation-based control the H-infinity Kalman Filter is used as a robust observer. The nonlinear optimal control scheme for the parallel double inverted pendulum achieves fast and accurate tracking of reference setpoints under moderate variations of the control inputs.
espanolEste articulo describe un nuevo enfoque de los laboratorios para sistemas industriales, concretamente, los laboratorios hibridos, que son una mezcla de laboratorios reales y virtuales. Los laboratorios hibridos propuestos tienen dispositivos de control fisicos en la parte real, y componentes y procesos simulados en la parte virtual. A traves de la combinacion y conexion entre ambas partes, se puede aprovechar las ventajas proporcionadas por laboratorios reales y virtuales. Se ha desarrollado una arquitectura para el aprendizaje interactivo en automatizacion y control a traves de la herramienta Easy Java / JavaScript Simulations (EjsS), el protocolo de comunicacion Modbus y un Controlador Logico Programable (PLC). El modelo virtual es simulado por EjsS, la comunicacion y el manejo de variables se realiza a traves del protocolo Modbus para intercambiar los valores de las entradas y salidas entre la planta virtual y el PLC. Para ilustrar esta arquitectura, se presentan dos casos de estudio: la automatizacion de una celula robotica y el control de un nivel de tanque. EnglishThis paper describes a new approach of laboratories for industrial systems, specifically, hybrid laboratories, which are a mix of real and virtual laboratories. The hybrid labs proposed have physical control devices in the real part, and simulated components and processes in the virtual part. Through the combination and connection between both parts, it can take advantage provided by both real and virtual laboratory. An architecture for interactive learning in Automation and Control has been developed through the Easy Java/JavaScript Simulations (EjsS) tool, Modbus communication protocol and a Programming Logic Controller (PLC). The virtual model is simulated by EjsS, the communication and handling of variables is done through the Modbus protocol to exchange the values of the inputs and outputs between the virtual plant and the PLC. To illustrate this architecture, two case studies are presented: the automation of a robotic cell and the control of a tank level. Laboratory practices have been developed following for several courses following some learning objectives.
A nonlinear optimal (H-infinity) control approach is developed for the model of the ballbot. This robotic system consists of a rolling sphere with a rigid body, in the form of an inverted pendulum, mounted on top of the sphere. Because of the nonlinearities and underactuation that are due to the dynamics of both the rolling sphere and of the rotational motion of the rigid body, control of the ballbot is a non-trivial problem. In the proposed control method, the dynamic model of the ballbot undergoes first approximate linearization around a temporary operating point which is updated at each iteration of the control algorithm. The linearization process makes use of first-order Taylor series expansion and relies also on the computation of the Jacobian matrices of the state-space model of the robotic system. A stabilizing H-infinity feedback controller is designed for the approximately linearized description of the ballbot. An algebraic Riccati equation is solved at each time-step of the control method so as to compute the controller's feedback gains. Through Lyapunov analysis the stability properties of the control scheme are proven. Besides, through the article's results it is demonstrated that the control method retains the advantages of linear optimal control, that is fast and accurate tracking of the reference setpoints under moderate variations of the control inputs.
This paper presents a free Java software platform which enables users to easily create advanced robotic applications together with image processing.This novel tool is composed of two layers: 1) Easy Java Simulations (EJS), an open-source tool which provides support for creating applications with a full 2D/3D interactive graphical interface, and 2) EjsRL, a high-level Java library specifically designed for EJS which provides a complete functional framework for modeling of arbitrary serial-link manipulators and computer vision algorithms.The combination of both components sets up a software architecture which contains a high number of functionalities in the same platform to develop complex simulations in robotics and computer vision fields.
En este artículo se describe la formulación, implementación y experimentación de un sistema de control visual dinámico aplicado a un robot de 6 grados de libertad. Se propone una arquitectura hardware basada en FPGAs para la implementación de los controladores. Con el objetivo de limitar la latencia del controlador se ha implementado en la FPGA no sólo el controlador sino también la captura y procesamiento de la información visual. Se hace uso de las capacidades de procesamiento paralelo de la FPGA para optimizar los diferentes componentes del sistema de control visual propuesto. Finaliza el artículo con los resultados experimentales obtenidos en tareas de posicionamiento de un robot Mitsubishi PA10 de 6 grados de libertad.
