Oscar Reinoso

A comparative evaluation of interest point detectors and local descriptors for visual SLAM

In this paper we compare the behavior of different interest point detectors and descriptors under the conditions needed to be used as landmarks in vision-based simultaneous localization and mapping (SLAM). We evaluate the repeatability of the detectors, as well as the invariance and distinctiveness of the descriptors, under different perceptual conditions using sequences of images representing planar objects as well as 3D scenes. We believe that this information will be useful when selecting an appropriate landmark detector and descriptor for visual SLAM.

Real-time collaboration of virtual laboratories through the Internet

Web-based learning environments are becoming increasingly popular in higher education. One of the most important web-learning resources is the virtual laboratory (VL), which gives students an easy way for training and learning through the Internet. Moreover, on-line collaborative communication represents a practical method to transmit the knowledge and experience from the teacher to students overcoming physical distance and isolation. Considering these facts, the authors of this document have developed a new dynamic collaborative e-learning system which combines the main advantages of virtual laboratories and collaborative learning practices. In this system, the virtual laboratories are based on Java applets which have embedded simulations developed in Easy Java Simulations (EJS), an open-source tool for teachers who do not need complex programming skills. The collaborative e-learning is based on a real-time synchronized communication among these Java applets. Therefore, this original approach provides a new tool which integrates virtual laboratories inside a synchronous collaborative e-learning framework. This paper describes the main features of this system and its successful application in a distance education environment among different universities from Spain.

A comparison of path planning strategies for autonomous exploration and mapping of unknown environments

To date, a large number of algorithms to solve the problem of autonomous exploration and mapping has been presented. However, few efforts have been made to compare these techniques. In this paper, an extensive study of the most important methods for autonomous exploration and mapping of unknown environments is presented. Furthermore, a representative subset of these techniques has been chosen to be analysed. This subset contains methods that differ in the level of multi-robot coordination and in the grade of integration with the simultaneous localization and mapping (SLAM) algorithm. These exploration techniques were tested in simulation and compared using different criteria as exploration time or map quality. The results of this analysis are shown in this paper. The weaknesses and strengths of each strategy have been stated and the most appropriate algorithm for each application has been determined.

Motion planning of a climbing parallel robot

Proposes an 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 Hernandez University of Elche (Alicante), Spain.

Parallel robots for autonomous climbing along tubular structures

Abstract This paper proposes the application of the Gough–Stewart (G–S) platform as a climbing robot. The idea of using the parallel G–S platform as a climbing robot is a novel solution to carry out tasks that imply a high risk for workers who have to climb on tubular structures. Some mechanical adaptations allow to convert the G–S platform in an autonomous and teleoperated robot capable to move autonomously along tubular structures (posts, steel wires of bridges, trunks of palms, pipes, etc.) or inside of fluid conducting pipes. To show the capacity of using this G–S platform as climbing robot we propose several mechanical designs capable of climbing through these tubular structures. Taking into account these designs and their functionality, we study the dynamics of some different configurations of these robots. In the second part of the paper we present a first prototype used as a climbing robot, developed to climb on palm trunks. Technical specifications of the system are presented and the control scheme is analyzed. Finally several experiments show the capability of this parallel robot to climb on tubular structures.

A climbing parallel robot: a robot to climb along tubular and metallic structures

This article presents the promising applications that can be obtained from parallel robots for climbing. It explores the most important aspects of the mechanical design and control of climbing parallel robots (CPRs) based on the Stewart-Goughs (S-G) platform for tasks in tubular or metallic structures.

Generalized control method by state convergence for teleoperation systems with time delay

In this paper a generalized design and control method for teleoperation systems with communication time delay is presented. The design method is based on the state space formulation and it allows to obtain the control parameters for any teleoperation system where the master and the slave manipulators would be represented by nth-order linear differential equations. Through state convergence between the master and the slave, the control system allows the slave to follow the master inspite of the time delay. The method is also able to establish the desired dynamics of this convergence and the dynamics of the slave manipulator. Experimental results are presented showing the validity of the proposed design and control method.

Interest Point Detectors for Visual SLAM

In this paper we present several interest points detectors and we analyze their suitability when used as landmark extractors for vision-based simultaneous localization and mapping (vSLAM). For this purpose, we evaluate the detectors according to their repeatability under changes in viewpoint and scale. These are the desired requirements for visual landmarks. Several experiments were carried out using sequence of images captured with high precision. The sequences represent planar objects as well as 3D scenes.

Improving Data Association in Vision-based SLAM

This paper presents an approach to vision-based simultaneous localization and mapping (SLAM). Our approach uses the scale invariant feature transform (SIFT) as features and applies a rejection technique to concentrate on a reduced set of distinguishable, stable features. We track detected SIFT features over consecutive frames obtained by a stereo camera and select only those features that appear to be stable from different views. Whenever a feature is selected, we compute a representative feature given the previous observations. This approach is applied within a Rao-Blackwellized particle filter to make the data association easier and furthermore to reduce the number of landmarks that need to be maintained in the map. Our system has been implemented and tested on data gathered with a mobile robot in a typical office environment. Experiments presented in this paper demonstrate that our method improves the data association and in this way leads to more accurate maps

Dynamic analysis for a teleoperation system with time delay

In this paper, the dynamic analysis for a teleoperation system with time delay is presented. The teleoperation system is controlled using a new design method through state convergence. This control method allows establishing the dynamics of the slave and the master-slave error. To perform the dynamic analysis, the influence of the slave and the error poles location in the dynamic behavior of the teleoperation system is studied. Also the robustness of the method control against slightly variations in the design parameters is analyzed.