José M. Sebastián

Visual 3-D SLAM from UAVs

The aim of the paper is to present, test and discuss the implementation of Visual SLAM techniques to images taken from Unmanned Aerial Vehicles (UAVs) outdoors, in partially structured environments. Every issue of the whole process is discussed in order to obtain more accurate localization and mapping from UAVs flights. Firstly, the issues related to the visual features of objects in the scene, their distance to the UAV, and the related image acquisition system and their calibration are evaluated for improving the whole process. Other important, considered issues are related to the image processing techniques, such as interest point detection, the matching procedure and the scaling factor. The whole system has been tested using the COLIBRI mini UAV in partially structured environments. The results that have been obtained for localization, tested against the GPS information of the flights, show that Visual SLAM delivers reliable localization and mapping that makes it suitable for some outdoors applications when flying UAVs.

Telerobotic system for live-power line maintenance: ROBTET

Abstract This paper is focused on a telerobotic application for the maintenance of electrical live-power lines, called “ROBTET”. Maintenance-related tasks are of great relevance for utilities companies, as their goal of achieving a good service quality depends to a great extent on maintenance and inspection issues. On live lines up to 69 kV , the tasks are carried out by teleoperated robots. These manipulators are teleoperated by a human operator sitting in a vehicle required to place the telerobotic system over the desired line. In this paper, the main developments in live-line teleoperated systems are mentioned, followed by a detailed description of the ROBTET. This telerobotic system has been developed by the Universidad Politecnica de Madrid, in collaboration with Iberdrola and Cobra, a Spanish utility company and contractor, respectively. The ROBTET system has been in operation in the Spanish electricity network for over a year, which attests to the success of the prototype and also allows for the incorporation of improvements.

Ciclope Robot: Web-Based System to Remote Program an Embedded Real-Time System

This paper presents a particular case of a pedagogically successful, dynamic, and efficient remote laboratory. The aim of the remote laboratory is to learn how to program embedded real-time systems in a real machine such as a robot. The system supplies feedback information to the user through a Web browser and an ssh terminal. Likewise, the remote laboratory allows a high degree of interaction owing to a clear and simple interface. This type of telecontrol Web-based system generates strong interest among students. The following are the two main contributions of this system: The remote laboratory allows collaboration among students in order to solve the problem, and the usage of a free software architecture allows anyone to replicate and improve the laboratory.

Uncalibrated visual servoing using the fundamental matrix

This paper describes a new algorithm for visual control of an uncalibrated 3 DOF joint system, using two weakly calibrated fixed cameras. The algorithm estimates on-line the Image Jacobian, a matrix which linearly relates joint velocity and image feature velocity. In our experiments we prove that by using the fundamental matrix, robustness of the estimation in the presence of noise is significantly increased with respect to already existing algorithms in specialized literature.

RoboTenis: optimal design of a parallel robot with high performance

This paper presents the design of a parallel robot that is used to play table tennis. The object of this application is to evaluate the level of integration between high-speed robotic systems and vision systems in unknown and dynamic environments. The parallel robot is based on a DELTA robot. The optimization method uses a global condition index based on the condition number of the Jacobian matrix. Firstly, we present the geometric model and kinematic analysis of the parallel robot. The optimization defines the dimensions of the manipulator. Using ADAMS/spl reg/, we obtain the maximum speed of the end-effector and the maximum torque of the motors for a set of typical trajectories of the ball in table tennis. Finally, we display the prototype of the built manipulator.

CICLOPE CHEMICAL: A REMOTE LABORATORY TO CONTROL A SPECTROGRAPH

Abstract This paper presents an educational chemical laboratory accessible through the Internet. Its aim is providing remote access to a real spectrograph in order students carry out their practicals on distance, without restrictions of space or time, as if they were in the lab. Furthermore, teachers have full control of what students are doing, which is useful to evaluate. This lab has been used and tested with students of the 4 th year of the Industrial Engineering School (ETSII) of the Spanish Open University UNED (Universidad Nacional de Educacion a Distancia). The system uses Ciclope architecture, methodology and philosophy, which is intended for building remote labs as libre projects. This means that all the software used and made, and the hardware developed in this project is free under the GPL license and it is available in SVN server of Ciclope project web page ( http://www.ciclope.info ). Furthermore, any person who would like to use, copy, imitate, modify, improve or collaborate with this project, or with any other of Ciclope, can do it following the instructions in Ciclopes URL.

An Inexpensive Method for Kinematic Calibration of a Parallel Robot by Using One Hand-Held Camera as Main Sensor

This paper presents a novel method for the calibration of a parallel robot, which allows a more accurate configuration instead of a configuration based on nominal parameters. It is used, as the main sensor with one camera installed in the robot hand that determines the relative position of the robot with respect to a spherical object fixed in the working area of the robot. The positions of the end effector are related to the incremental positions of resolvers of the robot motors. A kinematic model of the robot is used to find a new group of parameters, which minimizes errors in the kinematic equations. Additionally, properties of the spherical object and intrinsic camera parameters are utilized to model the projection of the object in the image and thereby improve spatial measurements. Finally, several working tests, static and tracking tests are executed in order to verify how the robotic system behaviour improves by using calibrated parameters against nominal parameters. In order to emphasize that, this proposed new method uses neither external nor expensive sensor. That is why new robots are useful in teaching and research activities.

Vision-Based Control of the RoboTenis System

In this paper a visual servoing architecture based on a parallel robot for the tracking of faster moving objects with unknown trajectories is proposed. The control strategy is based on the prediction of the future position and velocity of the moving object. The synthesis of the predictive control law is based on the compensation of the delay introduced by the vision system. Demonstrating by experiments, the high-speed parallel robot system has good performance in the implementation of visual control strategies with high temporary requirements.

RoboTenis: design, dynamic modeling and preliminary control

The accomplishment of robotic tasks involving dynamical environments requires lightweight yet stiff structures, actuators allowing for high acceleration and high speed, fast sensor signal processing, and sophisticated control schemes which take into account the highly nonlinear robot dynamics. As a tool for the investigation of these issues we present the RoboTenis system. This system proposes the design and construction of a high-speed parallel robot that can perform complex tasks aided by a vision system. As a specialized application to demonstrate its speed and versatility we intend the robot to play table tennis. In this paper we present the design of the parallel robot, the dynamic modeling and the first control experiences. The results prove that the system is able to perform the desired task

A new method for the estimation of the image jacobian for the control of an uncalibrated joint system

This paper describes various innovative algorithms for the on-line estimation of the image jacobian, a matrix which linearly relates joint velocity and image feature velocity. We have applied them successfully to the static visual control of an uncalibrated 3 DOF joint system, using two weakly calibrated fixed cameras. The proposed algorithms prove to be particularly robust when image features are calculated with an average level of noise, and our results are clearly better than those obtained for already existing algorithms in specialized literature.