This work was funded by the Spanish MCYT project DPI2005-06222 “Diseno, implementacion y experimentacion de escenarios de manipulacion inteligentes para aplicaciones de ensamblado y desensamblado automatico” and by the project GV05/007: “Diseno y experimentacion de estrategias de control visual-fuerza para sistemas flexibles de manipulacion”.
This paper presents a novel control approach to dynamic visual servo control multi-fingered robotic hands for the manipulation performance of an object. The control approach allows the path tracking of the object motion by means of visual information and takes into account both the dynamics model of the robot hand and the grasping force of the fingertips. In addition, an optimal approach is employed to obtain the desired behaviour in the joint space based on an indicated cost function which determines how the control effort is distributed over the robot fingers' joints. Finally, authors show experimental verifications on a robotic manipulation system for some of the visual servo controllers derived from the control approach.
Abstract The control problem of the rotary double inverted pendulum (double Furuta pendulum) is nontrivial because of underactuation and strong nonlinearities in the associated state‐space model. The system has three degrees of freedom (one actuated and two unactuated joints) while receiving only one control input. In this article, a novel nonlinear optimal (H‐infinity) control approach is developed for the dynamic model of the rotary double inverted pendulum. First, the dynamic model of the double pendulum undergoes approximate linearization with the use of first‐order Taylor series expansion and through the computation of the associated Jacobian matrices. The linearization process takes place at each sampling instance around a temporary operating point which is defined by the present value of the system's state vector and by the last sampled value of the control inputs vector. At a next stage a stabilizing H‐infinity feedback controller is designed. To compute the controller's feedback gains an algebraic Riccati equation has to be solved at each time‐step of the control algorithm. The global stability properties of the control scheme are proven through Lyapunov analysis. To implement state estimation‐based control without the need to measure the entire state vector of the rotary double‐pendulum the H‐infinity Kalman filter is used as a robust state observer. The nonlinear optimal control method achieves fast and accurate tracking of setpoints by all state variables of the rotary double inverted pendulum under moderate variations of the control input.
Summary The article proposes a nonlinear optimal control method for the model of the wheeled inverted pendulum (WIP). This is a difficult control and robotics problem due to the system’s strong nonlinearities and due to its underactuation. First, the dynamic model of the WIP undergoes approximate linearization around a temporary operating point which is recomputed at each time step of the control method. The linearization procedure makes use of Taylor series expansion and of the computation of the associated Jacobian matrices. For the linearized model of the wheeled pendulum, an optimal ( H -infinity) feedback controller is developed. The controller’s gain is computed through the repetitive solution of an algebraic Riccati equation at each iteration of the control algorithm. The global asymptotic stability properties of the control method are proven through Lyapunov analysis. Finally, by using the H -infinity Kalman Filter as a robust state estimator, the implementation of a state estimation-based control scheme becomes also possible.
Este trabajo ha sido parcialmente financiado por el proyecto GV05/007 “Diseno y experimentacion de estrategias de control visual-fuerza para sistemas flexibles de manipulacion”.
This paper presents a non-destructive disassembly method. It tries to make up for limitations of other methods based on contact surfaces. It uses a contact surfaces graph and shows an algorithm to obtain the movement sequence needed for the disassembly of two objects, using a composition of transfer movement. It performs a second filter to obtain the exact disassembly direction from the group of directions obtained from the contact surfaces. The filter employs a mobile robotic heuristic to feedback the contact surface graph throughout the disassembly process. The heuristic generates an environment map to infer the region where the probability of collision with the other objects is lower. To achieve the disassembly the paper presents a method for modeling the elements implied in the disassembly process. This virtual model of the environment allows us to quickly process the elements and the simulation of the movements for disassembly. This model can be used to either schedule the disassembly process or to test, during the design stage, whether the products can be easily disassembled.
Autonomous manipulation in semi-structured environments where human operators can interact is an increasingly common task in robotic applications. This paper describes an intelligent multi-sensorial approach that solves this issue by providing a multi-robotic platform with a high degree of autonomy and the capability to perform complex tasks. The proposed sensorial system is composed of a hybrid visual servo control to efficiently guide the robot towards the object to be manipulated, an inertial motion capture system and an indoor localization system to avoid possible collisions between human operators and robots working in the same workspace, and a tactile sensor algorithm to correctly manipulate the object. The proposed controller employs the whole multi-sensorial system and combines the measurements of each one of the used sensors during two different phases considered in the robot task: a first phase where the robot approaches the object to be grasped, and a second phase of manipulation of the object. In both phases, the unexpected presence of humans is taken into account. This paper also presents the successful results obtained in several experimental setups which verify the validity of the proposed approach.
Tactile sensors play an important role in robotics manipulation to perform dexterous and complex tasks. This paper presents a novel control framework to perform dexterous manipulation with multi-fingered robotic hands using feedback data from tactile and visual sensors. This control framework permits the definition of new visual controllers which allow the path tracking of the object motion taking into account both the dynamics model of the robot hand and the grasping force of the fingertips under a hybrid control scheme. In addition, the proposed general method employs optimal control to obtain the desired behaviour in the joint space of the fingers based on an indicated cost function which determines how the control effort is distributed over the joints of the robotic hand. Finally, authors show experimental verifications on a real robotic manipulation system for some of the controllers derived from the control framework.
The work proposed here tries to introduce a project-based learning methodology for the subject Sensing Systems of the master’s degree in Automation and Robotics at the University of Alicante. The heterogeneous conditions of the students and the combined face-to-face and online teaching requirements made the teachers change the current teaching model based only on theoretical classes and individual practical exercises, to a more flexible schedule following a Project-based active learning scheme. One of the problems that the teachers found in this subject and the master’s degree in general is the difference in knowledge between the students in the different areas that the subject cover. This is due to the heterogeneity of students who come from different degrees from various universities and even countries. Also, in this course, the teachers must deal with the situation that the incoming students graduated in the Degree in Robotics Engineering (University of Alicante) already have most of the knowledge that this and other subjects cover. This project-based learning is therefore intended to promote self-teaching to allow the most advanced students to get a deep teaching experience while the others learn the basics of the subject. The other great challenge the teachers must deal with is the adaptation to the current face-to-face and online combined teaching classes. As the proposed projects must be carried out using the robotics laboratory hardware, a carefully designed schedule for sharing the resources was made, with special attention to the current cleaning requirements. All these factors make us think that project-based learning will allow all students to acquire the appropriate skills. To evaluate the advantages and disadvantages of this proposal two surveys were carried out, one for the students and another for the current and previous teachers of the subject. The results show how this strategy got good results even for the students with no prior knowledge of the subject area. © 2021 University of Minho. All rights reserved.
En este articulo se describe un laboratorio remoto empleado en el aprendizaje practico de la asignatura Sistemas de Control Automatico, que se imparte en el Master Universitario en Automatica y Robotica de la Universidad de Alicante. La aplicacion desarrollada permite a los estudiantes practicar a distancia diferentes conceptos teoricos utilizando un modelo hardware de un proceso industrial real consistente en un sistema de bombeo. En el articulo se describe las caracteristicas mas importantes de este laboratorio remoto, destacando su capacidad para realizar la evaluacion automatica del estudiante. La aplicacion propone un conjunto de experiencias practicas que los alumnos deben resolver haciendo uso del laboratorio remoto. Ademas, la aplicacion ofrece una retroalimentacion que guia al estudiante en los conceptos para mejorar en su aprendizaje. Esta informacion puede ser utilizada por los estudiantes para llevar a cabo un auto-aprendizaje. El documento concluye con un estudio que describe el impacto educativo acerca del uso de esta herramienta en el aprendizaje de los estudiantes.
