GPCA vs. PCA in Recognition and 3-D Localization of Ultrasound Reflectors

In this paper, a new method of classification and localization of reflectors, using the time-of-flight (TOF) data obtained from ultrasonic transducers, is presented. The method of classification and localization is based on Generalized Principal Component Analysis (GPCA) applied to the TOF values obtained from a sensor that contains four ultrasound emitters and 16 receivers. Since PCA works with vectorized representations of TOF, it does not take into account the spatial locality of receivers. The GPCA works with two-dimensional representations of TOF, taking into account information on the spatial position of the receivers. This report includes a detailed description of the method of classification and localization and the results of achieved tests with three types of reflectors in 3-D environments: planes, edges, and corners. The results in terms of processing time, classification and localization were very satisfactory for the reflectors located in the range of 50–350 cm

Space Station RT and E Utilization Study

Descriptive information on a set of 241 mission concepts was reviewed to establish preliminary Space Station outfitting needs for technology development missions. The missions studied covered the full range of in-space technology development activities envisioned for early Space Station operations and included both pressurized volume and attached payload requirements. Equipment needs were compared with outfitting plans for the life sciences and microgravity user communities, and a number of potential outfitting additions were identified. Outfitting implementation was addressed by selecting a strawman mission complement for each of seven technical themes, by organizing the missions into flight scenarios, and by assessing the associated outfitting buildup for planning impacts

Amélioration de la précision et réduction des zones masquéees de capteurs à ultrasons grâce à l'utilistation de séquences complémentaires de Golay

Les systèmes sensoriels basés sur les capteurs à ultrasons présentent certaines contraintes qui ont tendance à réduire leur performance. Parmi les problèmes typiques, nous pouvons citer la faible précision des mesures et l'existence à l'avant des capteurs de zones masquées, zones où les réflecteurs ne peuvent pas être détectés si les capteurs sont utilisés comme émetteurs et récepteurs. Dans le but d'améliorer la précision des mesures réalisées par ces capteurs, les émissions sont le plus souvent codées par des séquences binaires. Les distances peuvent être alors déterminées en faisant appel à des techniques de corrélation. Dans ce cadre, ce travail présente les résultats obtenus lors de l'utilisation de séquences complémentaires de Golay, lesquelles permettent d'augmenter de manière significative la précision obtenue à partir d'un capteur à ultrasons isolé. Elles permettent également d'éliminer les zones masquées précédemment citées grâce à leurs caractéristiques d'autocorrélation. Ces deux fonctions seront très intéressantes dans l'optique d'une utilisation de capteurs à ultrasons dans le cadre d'associations sensorielles plus complexes.Sensorial systems based on ultrasonic transducers present some constraints, which reduce their performances. Typical problems are low precision in measurements, and the existence of a blind zone in front of transducers, where reflectors can not be detected if transducers are used as emitters and receivers. In order to improve the precision achieved by these transducers, binary sequences are often used to code the emission, so afterwards, distances can be determined using correlation techniques. The usage of Golay complementary sequences allows to increase remarkably the precision obtained by an isolated ultrasonic transducer. Also, it permits to eliminate the mentioned blind zone, thanks to their auto-correlation characteristics. These two features are very interesting in order to use ultrasonic transducers in more complex sensorial associations

Towards a bionic bat: A biomimetic investigation of active sensing, Doppler-shift estimation, and ear morphology design for mobile robots.

Institute of Perception, Action and BehaviourSo-called CF-FM bats are highly mobile creatures who emit long calls in which much of the energy is concentrated in a single frequency. These bats face sensor interpretation problems very similar to those of mobile robots provided with ultrasonic sensors, while navigating in cluttered environments. This dissertation presents biologically inspired engineering on the use of narrowband Sonar in mobile robotics. It replicates, using robotics as a modelling medium, how CF-FM bats process and use the constant frequency part of their emitted call for several tasks, aiming to improve the design and use of narrowband ultrasonic sensors for mobile robot navigation. The experimental platform for the work is RoBat, the biomimetic sonarhead designed by Peremans and Hallam, mounted on a commercial mobile platform as part of the work reported in this dissertation. System integration, including signal processing capabilities inspired by the bat’s auditory system and closed loop control of both sonarhead and mobile base movements, was designed and implemented. The result is a versatile tool for studying the relationship between environmental features, their acoustic correlates and the cues computable from them, in the context of both static, and dynamic real-time closed loop, behaviour. Two models of the signal processing performed by the bat’s cochlea were implemented, based on sets of bandpass filters followed by full-wave rectification and low-pass filtering. One filterbank uses Butterworth filters whose centre frequencies vary linearly across the set. The alternative filterbank uses gammatone filters, with centre frequencies varying non-linearly across the set. Two methods of estimating Doppler-shift from the return echoes after cochlear signal processing were implemented. The first was a simple energy-weighted average of filter centre frequencies. The second was a novel neural network-based technique. Each method was tested with each of the cochlear models, and evaluated in the context of several dynamic tasks in which RoBat was moved at different velocities towards stationary echo sources such as walls and posts. Overall, the performance of the linear filterbank was more consistent than the gammatone. The same applies to the ANN, with consistently better noise performance than the weighted average. The effect of multiple reflectors contained in a single echo was also analysed in terms of error in Doppler-shift estimation assuming a single wider reflector. Inspired by the Doppler-shift compensation and obstacle avoidance behaviours found in CF-FM bats, a Doppler-based controller suitable for collision detection and convoy navigation in robots was devised and implemented in RoBat. The performance of the controller is satisfactory despite low Doppler-shift resolution caused by lower velocity of the robot when compared to real bats. Barshan’s and Kuc’s 2D object localisation method was implemented and adapted to the geometry of RoBat’s sonarhead. Different TOF estimation methods were tested, the parabola fitting being the most accurate. Arc scanning, the ear movement technique to recover elevation cues proposed by Walker, and tested in simulation by her, Peremans and Hallam, was here implemented on RoBat, and integrated with Barshan’s and Kuc’s method in a preliminary narrowband 3D tracker. Finally, joint work with Kim, K¨ampchen and Hallam on designing optimal reflector surfaces inspired by the CF-FM bat’s large pinnae is presented. Genetic algorithms are used for improving the current echolocating capabilities of the sonarhead for both arc scanning and IID behaviours. Multiple reflectors around the transducer using a simple ray light-like model of sound propagation are evolved. Results show phase cancellation problems and the need of a more complete model of wave propagation. Inspired by a physical model of sound diffraction and reflections in the human concha a new model is devised and used to evolve pinnae surfaces made of finite elements. Some interesting paraboloid shapes are obtained, improving performance significantly with respect to the bare transducer

Mechatronic design of an Explosive Ordnance Disposal Robot

Thesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2005Includes bibliographical references (leaves: 55-56)ix, 58 leavesThis study concerns with the design of an Explosive Ordnance Disposal (EOD) Robot which is controlled in task space and with the combined sensor system the robot is capable of autonomous navigation. The robot is composed of 4 different gripping apparatus attached to a 4 degree of freedom manipulator arm which is controlled in task space and a mobile platform which provides the mobility of the EOD robot in the operation field. Since the manipulator arm of the robot is controlled in task space apart from the control system of current EOD robots, the explosive ordnance disposal task which requires high precision and dexterity can be accomplished much faster and more accurate.In addition to improvements in the control system, a combined sensory system named VS-GPS is designed for autonomous navigation of the EOD robot by combining vision system, sonar system and GPS to operate in outdoor fields. In order to achieve the most feasible sensor system, all combinations of most common five conventional sensor systems are evaluated, and VS-GPS is found to be the most effective combined sensor system design.Design of the EOD robot and sensor system includes the solid modeling of the robot using a computer program, Solidworks, strength analysis, mathematical modeling of manipulator arm and evaluation of conventional sensor systems for an optimum combination of sensor systems especially for autonomous outdoor navigation of the robot

3D indoor positioning of UAVs with spread spectrum ultrasound and time-of-flight cameras

Este trabajo propone el uso de un sistema híbrido de posicionamiento acústico y óptico en interiores para el posicionamiento 3D preciso de los vehículos aéreos no tripulados (UAV). El módulo acústico de este sistema se basa en un esquema de Acceso Múltiple por División de Código de Tiempo (T-CDMA), en el que la emisión secuencial de cinco códigos ultrasónicos de espectro amplio se realiza para calcular la posición horizontal del vehículo siguiendo un procedimiento de multilateración 2D. El módulo óptico se basa en una cámara de Tiempo de Vuelo (TOF) que proporciona una estimación inicial de la altura del vehículo. A continuación se propone un algoritmo recursivo programado en un ordenador externo para refinar la posición estimada. Los resultados experimentales muestran que el sistema propuesto puede aumentar la precisión de un sistema exclusivamente acústico en un 70-80% en términos de error cuadrático medio de posicionamiento.This work proposes the use of a hybrid acoustic and optical indoor positioning system for the accurate 3D positioning of Unmanned Aerial Vehicles (UAVs). The acoustic module of this system is based on a Time-Code Division Multiple Access (T-CDMA) scheme, where the sequential emission of five spread spectrum ultrasonic codes is performed to compute the horizontal vehicle position following a 2D multilateration procedure. The optical module is based on a Time-Of-Flight (TOF) camera that provides an initial estimation for the vehicle height. A recursive algorithm programmed on an external computer is then proposed to refine the estimated position. Experimental results show that the proposed system can increase the accuracy of a solely acoustic system by 70–80% in terms of positioning mean square error.• Gobierno de España y Fondos para el Desarrollo Regional Europeo. Proyectos TARSIUS (TIN2015-71564-C4-4-R) (I+D+i), REPNIN (TEC2015-71426-REDT) y SOC-PLC (TEC2015-64835-C3-2-R) (I+D+i) • Junta de Extremadura, Fondos FEDER y Fondo Social Europeo. Proyecto GR15167 y beca predoctoral 45/2016 Exp. PD16030peerReviewe