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In this paper, a visual servoing for the tracking of objects in a plane using a fixed camera system is shown. The method proposed of tracking makes use of a variable number of trackers determined automatically. The integration of the predictions of each of them affords a flexible and robust system of tracking. The studies of efficiency carried out reflect that the delays produced are suitable for use in visual servoing. The proposed system can be generalized to tracking three-dimensional objects with movable cameras.

This paper presents a novel planner for dexterous manipulation with a multi-fingered robotic hand. This planner receives as input an initial grasp of the object and a desired trajectory of the object in task space (position and orientation). The planner computes the movements of the fingers which are required to move the object along this trajectory without breaking contacts. It uses a triangle mesh representation of the surfaces of the fingers and the object and a new contact evolution graph in order to compute all the possible transitions between the contact primitives of their surfaces. This planner have been implemented as a program which communicates with a five-fingered hand in order to test them in real manipulation tasks.

Este artículo analiza diferentes experiencias docentes que tienen como finalidad el aprendizaje de la robótica en el mundo universitario. Estas experiencias se plasman en el desarrollo de varios cursos y asignaturas sobre robótica que se imparten en la Universidad de Alicante. Para el desarrollo de estos cursos, los autores han empleado varias plataformas educativas, algunas de implementación propia, otras de libre distribución y código abierto. El objetivo de estos cursos es enseñar el diseño e implementación de soluciones robóticas a diversos problemas que van desde el control, programación y manipulación de brazos robots de ámbito industrial hasta la construcción y/o programación de mini-robots con carácter educativo. Por un lado, se emplean herramientas didácticas de última generación como simuladores y laboratorios virtuales que flexibilizan el uso de brazos robots y por otro lado, se hace uso de competiciones y concursos para motivar al alumno haciendo que ponga en práctica las destrezas aprendidas, mediante la construcción y programación de mini-robots de bajo coste., This paper discusses different teaching experiences which aims are the learning robotics in the university. These experiences are reflected in the development of several robotics courses and subjects at the University of Alicante. The authors have created various educational platforms or they have used tools of free distribution and open source for the implementation of these courses. The main objetive of these courses is to teach the design and implementation of robotic solutions to solve various problems not only such as the control, programming and handling of robot but also the assembly, building and programming of educational mini-robots. On the one hand, new teaching tools are used such as simulators and virtual labs which make flexible the learning of robot arms. On the other hand, competitions are used to motivate students because this way, the students put into action the skills learned through building and programming low-cost mini-robots.

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.

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.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The use of a robot arm for industry is a very common problem. A great quantity of these robots have to have a remote human controller to achieve its task successfully. The user knows what is happening with the robot arm through sensors. This information has to arrive to the user and if it consists of a video then the system needs a high bandwidth to carry it to the user in real-time. The present system uses a simulation feedback instead of video information; this type of feedback gets as much information as a video with a lower bandwidth. The simulation of the system is based on virtual reality modeling feedback language (VRML) to model the robot arm which reproduces the movements of the real robot. This method of feedback has the advantage of required little information to afford the user a real approach to the system. The proposed system lets the user move the robot arm with different point-to-point trajectories and different possibilities of movement. The aim of this kind of laboratory is to facilitate the access for students and professionals in the field of robotics. This system is used for teaching university students the themes of robotics. It improves the training of the students permitting them access to a real robot which would be impossible for universities to afford if each student needed his own robot to practice. This paper presents a remote laboratory approach for experimentation with a real robot, which uses the communication techniques of the web.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

An algorithm for allocating and scheduling tasks in multiprocessor environments is presented. Its main characteristic is its orientation towards machine vision applications. In this sense it deals with the peculiarities of systems which combine generic-type processors with Image Acquisition and Processing Boards. The main goal of the algorithm is total processing time reduction; such are the requirements when we deal with automated industrial inspection applications. By simultaneously tackling the phases of allocation and scheduling, the results obtained are better than those offered by traditional algorithms. The system is applied to a process of citrus fruit inspection, and its performances are also evaluated over randomly generated task graphs.

In this paper, we present the results of the extension of the mathematical morphology to color images by treating multi-channel data as vectors. The approach presented here uses the HSI and related color spaces (intuitives). A modification of the lexicographical order for vectorial processing is developed. The importance of this new method lies on automatic selection of elements of the HSI and related color spaces to form an ordering structure. The achievement of the algorithm is realized through the introduction of a weight factor to reduce the high preference of the first component of the classic lexicographical order. Experimental results demonstrate the improvement of this new method.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This paper describes a vergence control algorithm for a 3D stereo recovery system. This work has been developed within framework of the project ROBTET. This project has the purpose of designing a Teleoperated Robotic System for live power lines maintenance. The tasks involved suppose the automatic calculation of path for standard tasks, collision detection to avoid electrical shocks, force feedback and accurate visual data, and the generation of collision free real paths. To accomplish these tasks the system needs an exact model of the environment that is acquired through an active stereoscopic head. A cooperative algorithm using vergence and stereo correlation is shown. The proposed system is carried out through an algorithm based on the phase correlation, trying to keep the vergence on the interest object. The sharp vergence changes produced by the variation of the interest objects are controlled through an estimation of the depth distance generated by a stereo correspondence system. In some elements of the scene, those aligned with the epipolar plane, large errors in the depth estimation as well as in the phase correlation, are produced. To minimize these errors a laser lighting system is used to help fixation, assuring an adequate vergence and depth extraction.

A fully integrated development tool for computer vision systems has been built in the framework of this paper. There are many applications that help the user in the design of such systems, using graphical interfaces and function libraries. Even in some cases, the final source code can be generated by these applications. This paper goes a step beyond; it allows the development of computer vision systems from a distributed environment. Besides, and as a distinctive characteristic with regard to other similar utilities, the system is able to automatically optimize task scheduling and assignment, depending on the available hardware.

In the last years aperture synthesis interferometric radiometers have received a special attention by space agencies as a feasible solution to passive monitoring of the Earth at low frequencies (L-band), where classical total power radiometers would require heavy steerable antennas to meet the spatial resolution requirements (10 - 20 Km), from a low polar orbit. While the performance of such instruments is well known in the radioastronomy field, its application to Earth remote sensing is quite new. The study of different array structures, system errors, calibration and inversion methods and instrument global performance requires the implementation of a simulator of a two-dimensional space borne interferometric radiometer. It allows us to analyze not only its snap shot radiometric accuracy, but also its improvement by means of pixel averaging, that is, the averaging of the common pixels recovered in a sequence of consecutive brightness temperature images. The simulations performed use the system parameters of the planned MIRAS (microwave imaging radiometer by aperture synthesis) instrument, a Y-shaped array with 43 antennas per arm spaced 0.89 lambda, currently under study by the European Space Agency.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Many inspection methods using computer vision have been developed, although in many of them the results obtained do not have the desired accuracy. In order to increase the system precision, two different solutions can be considered: the use of a more powerful image acquisition equipment and a solution that consists in developing algorithms that allow us to increase the accuracy of certain characteristics of the image. This paper is focused on setting a model that takes into account all the different signals involved in the image processing. It also defines the basis for the reconstruction of images in those areas with high content of information, such as edges, and more specifically those edges with a high change of intensity. In the image acquisition process, the input information is perfectly defined in a continuous domain and a discrete image is obtained as output, although distorted by the effects of the lenses, electrical sensor and the digitizer. This paper defines the conditions that the sampling process must satisfy in order to make possible the reconstruction of step edges using non-linear reconstruction filters in gray level images.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This paper presents a method for minimizing the total elapsed time spent by n tasks running on m differents processors working in parallel. The developed algorithm not only minimizes the total elapsed time but also reduces the idle time and waiting time of in-process tasks. This condition is very important in some applications of computer vision in which the time to finish the total process is particularly critical -- quality control in industrial inspection, real- time computer vision, guided robots. The scheduling algorithm is based on the use of two matrices, obtained from the precedence relationships between tasks, and the data obtained from the two matrices. The developed scheduling algorithm has been tested in one application of quality control using computer vision. The results obtained have been satisfactory in the application of different image processing algorithms.