A detection method of intersections for determining overlapping using active vision

Sometimes, the presence of objects difficult the observation of other neighboring objects. This is because part of the surface of an object occludes partially the surface of another, increasing the complexitiy in the recognition process. Therefore, the information which is acquired from scene to describe the objects is often incomplete and depends a great deal on the view point of the observation. Thus, when any real scene is observed, the regions and the boundaries which delimit and dissociate objects from others are not perceived easily. In this paper, a method to discern objects from others, delimiting where the surface of each object begins and finishes is presented. Really, here, we look for detecting the overlapping and occlusion zones of two or more objects which interact among each other in a same scene. This is very useful, on the one hand, to distinguish some objects from others when the features like texture colour and geometric form are not sufficient to separate them with a segmentation process. On the other hand, it is also important to identify occluded zones without a previous knowledge of the type of objects which are wished to recognize. The proposed approach is based on the detection of occluded zones by means of structured light patterns projected on the object surfaces in a scene. These light patterns determine certain discontinuities of the beam projections when they hit against the surfaces becoming deformed themselves. So that, such discontinuities are taken like zones of boundary of occlusion candidate regions

Contact mechanics applied to the machining of thin rings

Precision machining of thin rings is of key importance in the performance of many mechanical components such as bearings, rings, turbines, etc. An important factor to take into account is to know the influence of the clamping forces values at different angular positions of the workpiece in the geometrical tolerances after machining. The lower the clamping force, better tolerances will be achieved, but with the disadvantage of reducing friction force and, therefore, increasing the risk of slipping. Therefore, achieving a minimum but safe clamping force is a key factor to control the process. This paper presents some contributions of contact mechanics to the determination of an optimum clamping force. A subsequent methodology is applied that takes into account model of bulk deformation and local contact stresses and experimental data with the object of obtain the optimum torque applied to the chuck.The authors would like to thank the Basque Government for supporting this work made under the ETORTEK Program within the MARGUNE CRC framework while the first author was a visiting professor at TECNUN

Detection of partial occlusions of assembled components to simplify the disassembly tasks

An automatic disassembly cell requires of a computer vision system for recognition and localization of the products and each of theirs components. The detection of occlusions adds more information to the knowledge base to identify components and products, and generate a trustworthy and precise relational model (generic graph of hierarchic relations among the different components that make up the product). In this paper, a method to detect partial occlusions in assembled components is presented. This method is based on the fusion of regions and edges information, and it offers a certain degree of simplification for the recognition and modelled of the disassembly tasks, of the set of components which compose the product. The proposed approach to detect regions is a hybrid approach between RGB and HSV spaces. The bi-dimensional histogram V/S is employed for the selection of the appropriate thresholds which serve as an aid to diminish the influence of the highlights and shadows in images. The goal of this paper is to present an approach for the detection of occlusions in assembled components from a combination of HSV and RGB spaces, a bi-dimensional histogram and an edge detector.This work was funded by the following Spanish MCYT project “DESAURO: Desensamblado Automático Selectivo para Reciclado mediante Robots Cooperativos y Sistema Multisensorial” (MCYT (DPI2002-02103)

Motion planning of a climbing parallel robot

This paper proposes a novel application of the Stewart–Gough parallel platform as a climbing robot and its kinematics control to climb through long structures describing unknown spatial trajectories, such as palm trunks, tubes, etc. First, the description and design of the climbing parallel robot is presented. Second, the inverse and forward kinematics analysis of a mobile six-degrees-of-freedom parallel robot is described, based on spatial constraint formulation. Finally, the gait pattern and the climbing strategy of the parallel robot is described. The information from this research is being used in an actual climbing parallel robot design at Miguel Hernández University of Elche (Alicante), Spain.This paper was recommended for publication by Associate Editor M. Shoham and Editor I. Walker upon evaluation of the reviewers’ comments. This work was supported by the Spanish Ministry of Education and Culture under Project 1FD1997-1338

Avances en el desarrollo de un robot trepador de estructuras cilíndricas

En este artículo se presentan los avances alcanzados en la realización de un segundo prototipo para el diseño de un robot trepador sobre estructuras cilíndricas alargadas. Se ha realizado un nuevo diseño que posibilita un control más robusto de la estructura mecánica así como una mejor y adecuada maniobrabilidad. Asimismo se presenta el algoritmo utilizado para el control de trayectorias en tiempo real basado en la medida estimada del centro de la estructura cilíndrica por la que asciende el robot mediante el empleo de unos sensores de ultrasonidos en cada una de las bases del robot.El trabajo presentado en este artículo se ha realizado gracias a la financiación aportada por el Ministerio de Educación y Cultura (Dirección General de Enseñanza Superior e Investigación Científica) para el desarrollo del proyecto de investigación ‘Robot Trepador para mantenimiento de palmerales y de estructuras cilíndricas alargadas’ 1FD1997-1338

Enhanced Positioning Algorithm Using a Single Image in an LCD-Camera System by Mesh Elements' Recalculation and Angle Error Orientation

In this article, we present a method to position the tool in a micromachine system based on a camera-LCD screen positioning system that also provides information about angular deviations of the tool axis during its running. Both position and angular deviations are obtained by reducing a matrix of LEDs in the image to a single rectangle in the conical perspective that is treated by a photogrammetry method. This method computes the coordinates and orientation of the camera with respect to the fixed screen coordinate system. The used image consists of 5 × 5 lit LEDs, which are analyzed by the algorithm to determine a rectangle with known dimensions. The coordinates of the vertices of the rectangle in space are obtained by an inverse perspective computation from the image. The method presents a good approximation of the central point of the rectangle and provides the inclination of the workpiece with respect to the LCD screen reference system of coordinates. A test of the method is designed with the assistance of a Coordinate Measurement Machine (CMM) to check the accuracy of the positioning method. The performed test delivers a good accuracy in the position measurement of the designed method. A high dispersion in the angular deviation is detected, although the orientation of the inclination is appropriate in almost every case. This is due to the small values of the angles that makes the trigonometric function approximations very erratic. This method is a good starting point for the compensation of angular deviation in vision based micromachine tools, which is the principal source of errors in these operations and represents the main volume in the cost of machine elements’ parts.The authors want to thank the University Center of Defense at the Spanish Air Force Academy, MDE-UPCT, for financial suppor

Vergence control system for stereo depth recovery

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 .The work presented in this paper has been supported by electric utility IBERDROLA, S.A. under project PIE No. 132.198

Simultaneous trajectory and contact planning of a walking robot

[Resumen] En este artículo estudiamos la planificación simultánea de la trayectoria y de los apoyos de las patas de un robot en terrenos irregulares. Partimos del algoritmo A estrella (A*), que busca el camino más corto entre dos puntos. Primero se modela el terreno con un mallado triangular y se subdividen los triángulos, para tomar como espacio de búsqueda del A* los centroides de dichos triángulos. En segundo lugar, con respecto al A* original, se ha considerado la estabilidad del robot en cada centroide, de modo que el coste en un centroide sea penalizado si el robot es inestable y nulo si es estable. La estabilidad en cada punto de contacto se determina calculando que la reacción del terreno en ese punto esté contenida en un cono de fricción con una aproximación lineal. Por último, se obtiene la trayectoria, los puntos de contacto de cada pata, así como la postura del robot en cada posición.[Abstract] In this paper we study the simultaneous planning of the trajectory and leg supports of a robot on uneven terrain. We start with the A-star algorithm (A*), which searches for the shortest path between two points. First, the terrain is modelled with a triangular mesh and the triangles are subdivided to take the centroids of these triangles as the search space of the A*. Secondly, with respect to the original A*, the stability of the robot at each centroid is considered, so that the cost at a centroid is penalised if the robot is unstable and zero if it is stable. The stability at each contact point is determined by calculating that the ground reaction at that point is contained in a linear approximation of the friction cone. Finally, the trajectory, the contact points of each leg, as well as the robot's posture at each position are obtained.Generalitat Valenciana; INVEST/2022/432Generalitat Valenciana; CIGE/2021/177Ministerio de Ciencia e Innovación; MCIN/AEI/10.13039/50110001103

Overview and future trends of control education

Control education is a mature area in which many professors and researchers have worked hard to face the challenge of providing a versatile education with a strong scientific base. All this without losing sight of the needs of the industry; adapting the contents, methodologies, and tools to the continuous social and technological changes of our time. This article presents a reflection on the role of automatic control in today's society, a review of the traditional objectives of control education through seminal work in the area, and finally a review of the main current trends

Job-shop scheduling applied to computer vision

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 matrixes. 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