Estudi de comportaments socials amb eixams de robots reconfigurables

Els eixams de robots distribuïts representen tot un món de possibilitats al camp de la microrobòtica, però existeixen pocs estudis que n'analitzin els comportaments socials i les interaccions entre robots autònoms distribuïts. Aquests comportaments han de permetre assolir de la manera més efectiva possible un bon resultat. Prenent com a base l'objectiu esmentat, aquest treball detalla diferents polítiques de cerca i de reconfiguració dels robots i estudia els seus comportaments per tal de determinar quins d'ells són més útils per solucionar un problema concret amb les plagues d'erugues i corcs als camps de cigroneres.

Robotic, fluoroscopic or EMG assisted pedicle screw insertion. A CT based comparative study

Introduction: In order to improve safety of pedicle screw placement several techniques have been developed. More recently robotically assisted pedicle insertion has been introduced aiming at increasing accuracy. The aim of this study was to compare this new technique with the two main pedicle insertion techniques in our unit namely fluoroscopically assisted vs EMG aided insertion. Material and methods: A total of 382 screws (78 thoracic,304 lumbar) were introduced in 64 patients (m/f = 1.37, equally distributed between insertion technique groups) by a single experienced spinal surgeon. From those, 64 (10 thoracic, 54 lumbar) were introduced in 11 patients using a miniature robotic device based on pre operative CT images under fluoroscopic control. 142 (4 thoracic, 138 lumbar) screws were introduced using lateral fluoroscopy in 27 patients while 176 (64 thoracic, 112 lumbar) screws in 26 patients were inserted using both fluoroscopy and EMG monitoring. There was no difference in the distribution of scoliotic spines between the 3 groups (n = 13). Screw position was assessed by an independent observer on CTs in axial, sagittal and coronal planes using the Rampersaud A to D classification. Data of lumbar and thoracic screws were processed separately as well as data obtained from axial, sagittal and coronal CT planes. Results: Intra- and interobserver reliability of the Rampersaud classification was moderate, (0.35 and 0.45 respectively) being the least good on axial plane. The total number of misplaced screws (C&D grades) was generally low (12 thoracic and 12 lumbar screws). Misplacement rates were same in straight and scoliotic spines. The only difference in misplacement rates was observed on axial and coronal images in the EMG assisted thoracic screw group with a higher proportion of C or D grades (p <0.05) in that group. Recorded compound muscle action potentials (CMAP) values of the inserted screws were 30.4 mA for the robot and 24.9mA for the freehand technique with a CI of 3.8 of the mean difference of 5.5 mA. Discussion: Robotic placement did improve the placement of thoracic screws but not that of lumbar screws possibly because our misplacement rates in general near that of published navigation series. Robotically assisted spine surgery might therefore enhance the safety of screw placement in particular in training settings were different users at various stages of their learning curve are involved in pedicle instrumentation.

Análisis de prestaciones de sistemas de comunicaciones inalámbricas en aplicaciones de robótica: sistema software

Una característica importante de la robótica es la comunicación entre sistema base y robot que puede establecerse de forma remota. Ello representa la base del proyecto que se describe a continuación, el cual se descompone de dos partes, una por cada miembro del proyecto: sistema software y sistema hardware. En el sistema software analizaremos las diferentes tecnologías inalámbricas (características, funcionamiento, seguridad, etc.), se realizará una comparativa de los diferentes módulos de comunicación y finalmente decidiremos aquellos que nos interesa para la implementación en Radiofrecuencia (RF) y Bluetooth. En este sistema también estudiaremos la interfaz gráfica que se utilizará, así como los programas creados en este entorno para realizar las implementaciones. En el sistema hardware trataremos de realizar el control de dos periféricos de forma independiente, un servomotor y un sonar, que nos servirán como ejemplo para analizar una posible comunicación entre varios robots y un PC. Por lo tanto, en este apartado analizaremos a fondo los diferentes componentes que harán posible tanto la comunicación, vía RF y Bluetooth, como el control de los diferentes dispositivos.

Análisis de prestaciones de sistemas de comunicaciones inalámbricas en aplicaciones de robótica: sistema hardware

Una característica importante de la robótica es la comunicación entre sistema base y robot que puede establecerse de forma remota. Ello representa la base del proyecto que se describe a continuación, el cual se descompone de dos partes, una por cada miembro del proyecto: Sistema software y sistema hardware. En el sistema software analizaremos las diferentes tecnologías inalámbricas (características, funcionamiento, seguridad, etc.), se realizará una comparativa de los diferentes módulos de comunicación y finalmente decidiremos aquellos que nos interesa para la implementación en Radiofrecuencia (RF) y Bluetooth. En este sistema también estudiaremos la interfaz gráfica que se utilizará, así como los programas creados en este entorno para realizar las implementaciones. En el sistema hardware trataremos de realizar el control de dos periféricos de forma independiente, un servomotor y un sonar, que nos servirán como ejemplo para analizar una posible comunicación entre varios robots y un PC. Por lo tanto, en este apartado analizaremos a fondo los diferentes componentes que harán posible tanto la comunicación, vía RF y Bluetooth, como el control de los diferentes dispositivos.

Implementación de movimientos suaves en robots industriales mediante splines cúbicos: aplicación a un laboratorio remoto de robótica

La solución a los problemas de disponibilidad horaria para la realización de sesiones prácticas por parte de los estudiantes se encuentra en los laboratorios remotos, que permiten a estos interactuar con los elementos instalados en los laboratorios sin necesidad de estar presentes físicamente. Este proyecto pretende crear un laboratorio remoto para la asignatura “Robótica y Automatización Industrial” impartida en la ETSE, UAB, en el cual los estudiantes puedan ejecutar trayectorias de tipo spline cúbico en un brazo robot y observar a través de vídeo en tiempo real los movimientos del robot desde cualquier lugar con conexión a Internet.

Estudi de comportaments socials d'aixams robòtics amb aplicació a la neteja d'espais no estructurats

La intel·ligència d’eixams és una branca de la intel·ligència artificial que està agafant molta força en els últims temps, especialment en el camp de la robòtica. En aquest projecte estudiarem el comportament social sorgit de les interaccions entre un nombre determinat de robots autònoms en el camp de la neteja de grans superfícies. Un cop triat un escenari i un robot que s’ajustin als requeriments del projecte, realitzarem una sèrie de simulacions a partir de diferents polítiques de cerca que ens permetran avaluar el comportament dels robots per unes condicions inicials de distribució dels robots i zones a netejar. A partir dels resultats obtinguts serem capaços de determinar quina configuració genera millors resultats.

Diseño y puesta en marcha de un laboratorio remoto de robótica

Este proyecto surge de la iniciativa de mejorar la calidad docente de las prácticas en la asignatura Robótica y Automatización Industrial impartida en la ETSE (Escola Tècnica Superior d’Enginyeria) de la UAB, mediante un sistema innovador. El objetivo es sustituir las actuales prácticas, basadas en la realización de simulaciones en entorno MATLAB para verificar las ecuaciones que gobiernan a los robots manipuladores, por un entorno de prácticas más atractivo consistente en un robot manipulador real, que podrá ser programado para la realización de tareas de PPO (Pick and Place Operation).

Policy gradient based Reinforcement Learning for real autonomous underwater cable tracking

This paper proposes a field application of a high-level reinforcement learning (RL) control system for solving the action selection problem of an autonomous robot in cable tracking task. The learning system is characterized by using a direct policy search method for learning the internal state/action mapping. Policy only algorithms may suffer from long convergence times when dealing with real robotics. In order to speed up the process, the learning phase has been carried out in a simulated environment and, in a second step, the policy has been transferred and tested successfully on a real robot. Future steps plan to continue the learning process on-line while on the real robot while performing the mentioned task. We demonstrate its feasibility with real experiments on the underwater robot ICTINEU AUV

Autonomous underwater vehicle control using reinforcement learning policy search methods

Autonomous underwater vehicles (AUV) represent a challenging control problem with complex, noisy, dynamics. Nowadays, not only the continuous scientific advances in underwater robotics but the increasing number of subsea missions and its complexity ask for an automatization of submarine processes. This paper proposes a high-level control system for solving the action selection problem of an autonomous robot. The system is characterized by the use of reinforcement learning direct policy search methods (RLDPS) for learning the internal state/action mapping of some behaviors. We demonstrate its feasibility with simulated experiments using the model of our underwater robot URIS in a target following task

A system to evaluate the accuracy of a visual mosaicking methodology

When underwater vehicles navigate close to the ocean floor, computer vision techniques can be applied to obtain motion estimates. A complete system to create visual mosaics of the seabed is described in this paper. Unfortunately, the accuracy of the constructed mosaic is difficult to evaluate. The use of a laboratory setup to obtain an accurate error measurement is proposed. The system consists on a robot arm carrying a downward looking camera. A pattern formed by a white background and a matrix of black dots uniformly distributed along the surveyed scene is used to find the exact image registration parameters. When the robot executes a trajectory (simulating the motion of a submersible), an image sequence is acquired by the camera. The estimated motion computed from the encoders of the robot is refined by detecting, to subpixel accuracy, the black dots of the image sequence, and computing the 2D projective transform which relates two consecutive images. The pattern is then substituted by a poster of the sea floor and the trajectory is executed again, acquiring the image sequence used to test the accuracy of the mosaicking system

Towards a real-time vision-based navigation system for a small-class UUV

This paper deals with the problem of navigation for an unmanned underwater vehicle (UUV) through image mosaicking. It represents a first step towards a real-time vision-based navigation system for a small-class low-cost UUV. We propose a navigation system composed by: (i) an image mosaicking module which provides velocity estimates; and (ii) an extended Kalman filter based on the hydrodynamic equation of motion, previously identified for this particular UUV. The obtained system is able to estimate the position and velocity of the robot. Moreover, it is able to deal with visual occlusions that usually appear when the sea bottom does not have enough visual features to solve the correspondence problem in a certain area of the trajectory

Detection of matchings in a sequence of underwater images through texture analysis

This paper presents an approach to ameliorate the reliability of the correspondence points relating two consecutive images of a sequence. The images are especially difficult to handle, since they have been acquired by a camera looking at the sea floor while carried by an underwater robot. Underwater images are usually difficult to process due to light absorption, changing image radiance and lack of well-defined features. A new approach based on gray-level region matching and selective texture analysis significantly improves the matching reliability

Probabilistic sonar scan matching for an AUV

This paper proposes MSISpIC, a probabilistic sonar scan matching algorithm for the localization of an autonomous underwater vehicle (AUV). The technique uses range scans gathered with a Mechanical Scanning Imaging Sonar (MSIS), the robot displacement estimated through dead-reckoning using a Doppler velocity log (DVL) and a motion reference unit (MRU). The proposed method is an extension of the pIC algorithm. An extended Kalman filter (EKF) is used to estimate the robot-path during the scan in order to reference all the range and bearing measurements as well as their uncertainty to a scan fixed frame before registering. The major contribution consists of experimentally proving that probabilistic sonar scan matching techniques have the potential to improve the DVL-based navigation. The algorithm has been tested on an AUV guided along a 600 m path within an abandoned marina underwater environment with satisfactory results

Proposal of a parallel architecture for a motion detection algorithm

This paper proposes a parallel architecture for estimation of the motion of an underwater robot. It is well known that image processing requires a huge amount of computation, mainly at low-level processing where the algorithms are dealing with a great number of data. In a motion estimation algorithm, correspondences between two images have to be solved at the low level. In the underwater imaging, normalised correlation can be a solution in the presence of non-uniform illumination. Due to its regular processing scheme, parallel implementation of the correspondence problem can be an adequate approach to reduce the computation time. Taking into consideration the complexity of the normalised correlation criteria, a new approach using parallel organisation of every processor from the architecture is proposed