Design of obstacle detection and avoidance system for GUANAY II AUV

Postprint (published version

Obstacle detection algorithm of low computational cost for Guanay II AUV

Obstacle detection is one of the most important stages in the obstacle avoidance system. This work is focused to explain the operation of a designed and implemented for the overall detection of objects with low computational cost strategy. This strategy of low computational cost is based on performing a spatial segmentation of the information obtained by the SONAR and determine the minimum distance between the SONAR (AUV) and the obstacle.Postprint (published version

Design of the obstacle detection system with the SONAR MK3 on Guanay II AUV

Autonomous underwater vehicles (AUV) perform inspection missions and intervention in known and unknown environments, where it is necessary to ensure their safety. The AUV must have the ability to detect and avoid obstacles in the path of navigation. This article, an obstacle detection system for experimental Guanay II AUV is proposed, using a mechanical scanning SONAR Tritech Micron MK3. Since Guanay II operates autonomously, we have designed software that allows adjustment and control of the parameters of SONAR, and the acquisition and processing of the signals obtained. Experimental tests at sea have allowed to verify the correct operation of software designed, as well as, experimental tests in a controlled environment have allowed to determine the optimal values of the basic parameters of SONAR.Postprint (published version

Architecting the cyberinfrastructure for National Science Foundation Ocean Observatories Initiative (OOI)

The NSF Ocean Observatories Initiative (OOI) is a networked ocean research observatory with arrays of instrumented water column moorings and buoys, profilers, gliders and autonomous underwater vehicles (AUV) within different open ocean and coastal regions. OOI infrastructure also includes a cabled array of instrumented seafloor platforms and water column moorings on the Juan de Fuca tectonic plate. This networked system of instruments, moored and mobile platforms, and arrays will provide ocean scientists, educators and the public the means to collect sustained, time-series data sets that will enable examination of complex, interlinked physical, chemical, biological, and geological processes operating throughout the coastal regions and open ocean. The seven arrays built and deployed during construction support the core set of OOI multidisciplinary scientific instruments that are integrated into a networked software system that will process, distribute, and store all acquired data. The OOI has been built with an expectation of operation for 25 years.Peer Reviewe

Design obstacle detection system for AUV guanay II

The autonomous underwater vehicles (AUV) carry out inspection missions and intervention on known and unknown environments, where it is important to ensure their safety. The ability for obstacle detection and their avoidance during navigation is a requirement for safety. In this article is presented an obstacle detection system for the experimental vehicle Guanay II using mechanical scanning sonar, the Tritech Micron MK. Given that the Guanay II operates autonomously, a new software has been designed that allows adjustment, control, acquisition and processing of the sonar signals. Experimental tests done at sea have allowed us to verify the correct operation of the designed software, and to determine the optimal values of the fundamental parameters of sonar.Peer Reviewe

Diseño del sistema de navegación en inmersión del vehículo Guanay II para aplicaciones de detección y seguimiento de vertidos de hidrocarburos en zonas costeras

The study of the seas is a field of science that is in constant development. At the technological level, in recent years, important advances have been made in the design of platforms and measurement systems for oceanographic variables with significant improvements in their sensitivity, as well as in their capacity for spatial and temporal resolution. Currently, given the high costs of traditional techniques (oceanographic vessels), vehicles such as the ROV (Remotely Operated Vehicle), the ASV (Autonomous Surface Vehicle), the AUV (Autonomous Underwater Vehicle) and the AUV Glider are being used instead. From the point of view of the realization of oceanographic studies, the AUV offers more benefits due to its maneuverability and autonomy. An example of this would be the case study of the behavior of marine species based on environmental variables. In this situation, it is essential to carry out a good spatial resolution of multiple parameters, such as salinity, at various depths of the same water column. For the industrial and environmental conservation sectors, there is no specific use of the AUV. However, they can be used in order to obtain bathymetric maps and in the monitoring the specific physical-chemical characteristics of seawater. The motivation of this work is focused on the adaptation of the Guanay II vehicle as a platform for oceanographic measurements, with the ability to navigate in immersion, as well as reducing its possibility of collision with other vehicles or marine structures through its design and implementation of a detection and obstacle avoidance system. This adaptation would allow in the future to use the Guanay II vehicle to perform the detection and monitoring of polluting discharges of hydrocarbons in the sea, as well as monitoring oceanographic data for use in predictive models of the displacement of the spill. The Guanay II is a hybrid vehicle between AUV and ASV, that is, it sails on the surface and performs vertical dives at programmed points. Based on the motivation described, mechanical and electronic modifications have been made to the vehicle, accompanied by a process of study, analysis and mathematical development to obtain a hydrodynamic modeling uncoupled from the vehicle on the vertical plane. A vector propulsion immersion system has been designed and implemented using the lateral thrusters to control the vehicle's inclination during the dive. This system has been simulated in Matlab and implemented in the vehicle, which has allowed testing in the Olympic channel of Castelldefels, the results obtained in these tests have been satisfactory, allowing the vehicle to enter in immersion, remain in immersion during the time defined and then return to surface. On the other hand, in parallel to the design and implementation of this system. A new design has been carried out with the implementation of an obstacle detection and reactive avoidance system incorporated with a fuzzy system, based on a SONAR MK3. This system has been simulated and implemented in the control unit of the vehicle. This system has allowed multiple field tests, which were performed at the Olympic Castelldefels canal. The results obtained in these tests have been satisfactory, achieving in all cases the avoidance of the obstacles present in the navigation environment.El estudio de los mares es un campo de la ciencia que se encuentra en constante desarrollo. A nivel tecnológico, en los últimos años, se han producido importantes avances en el diseño de plataformas y sistemas de medición de variables oceanográficas con importantes mejoras en su sensibilidad, así como en su capacidad de resolución espacial y temporal. Actualmente, debido a los altos costos de las técnicas tradicionales (barcos oceanográficos) se ha incrementado el uso de vehículos no tripulados como los ROV (Remotely Operated Vehicle), los ASV (Autonomous Surface Vehicle), los AUV (Autonomous Underwater Vehicle) y los AUV Glider. Desde el punto de vista de la realización de estudios oceanográficos, los AUV ofrecen mayores beneficios por su mayor maniobrabilidad y autonomía. Un ejemplo de este caso es el estudio del comportamiento de las especies marinas en función de variables ambientales. En estos estudios es indispensable la medida con buena resolución espacial de múltiples parámetros, como la salinidad, a diversas profundidades de una misma columna de agua. Para los sectores industriales y de conservación del medio ambiente no hay un uso específico de los AUV. Pueden ser utilizados en la obtención de mapas batimétricos y en la monitorización de las características físico-químicas especificas del agua del mar. La motivación de este trabajo se centra en la adaptación del vehículo Guanay II como plataforma de mediciones oceanográficas, con la capacidad de navegar en inmersión, así como la reducción de la posibilidad de colisión contra otros vehículos o estructuras marinas mediante el diseño e implantación de un sistema de detección y evasión de obstáculos. Esta adaptación permitiría en el futuro utilizar el vehículo Guanay para realizar la detección y seguimiento de vertidos contaminantes de hidrocarburos en el mar, así como la monitorización de datos oceanográficos para su utilización en modelos predictivos del desplazamiento del vertido. El Guanay II es un vehículo híbrido entre AUV y ASV, es decir, navega en superficie y realiza inmersiones verticales en puntos programados. Con base en la motivación descrita se han realizado modificaciones mecánicas y electrónicas en el vehículo, acompañadas de un proceso de estudio, análisis y de desarrollo matemático para obtener un modelado hidrodinámico desacoplado del vehículo sobre el plano vertical. Se ha diseñado e implementado un sistema de inmersión por propulsión vectorial utilizando los propulsores laterales para controlar la inclinación del vehículo durante la inmersión. Este sistema ha sido simulado en Matlab e implementado en el vehículo, lo que ha permitido probarlo en el canal olímpico de Castelldefels, Los resultados obtenidos en estas pruebas han sido satisfactorios, permitiendo que el vehículo entre en inmersión, se mantenga en inmersión durante el tiempo definido y posteriormente vuelva a superficie. Por otra parte, en paralelo al diseño e implementación de este sistema, se ha llevado a cabo el diseño e implementación de un sistema de detección y evasión de obstáculos de arquitectura reactiva implementado bajo un sistema fuzzy, basado en un sensor SONAR MK3. Este sistema ha sido simulado e implementado en la unidad de control del vehículo. Esta implementación ha permitido realizar múltiples pruebas de campo, las cuales se realizaron en el canal olímpico de Castelldefels. Los resultados obtenidos en estas pruebas han sido satisfactorios, logrando en todos casos la evasión de los obstáculos presentes en el entorno de navegación

Contribution to the model and navigation control of an autonomous underwater vehicle

This thesis deals with the further development of an existing underwater vehicle for autonomous navigation. The vehicle was conceived to navigate over the sea surface and, at certain fixed points, to dive vertically in order to obtain a profile of a water column. The main objectives of the thesis are the improvement of the hardware and software of the vehicle in order to make it fully operational, and the design and implementation of control techniques for autonomous navigation. The problem of autonomous navigation is addressed first with the calculation of an hydrodynamic model in 3DoF. An extensive study about the selection of the coefficients is performed, using a linearized model. The calculation of the coefficients is done using two approaches: a geometric one and another one based on least squares techniques applied to experimental data obtained during sea trials. The least squares method gives satisfactory results and the simulations fits the experimental data. The resulting hydrodynamic model is completed with the physical constraints of the actuators of the vehicle. Solving the autonomous navigation problem requires the design of controllers for both the inner loop (dynamic) and the outer loop (kinematic). Several solutions based on type-1 TSK fuzzy control are presented for velocity control, yaw control, pure pursuit navigation, and path following. The fuzzy controller is used to manage different linear controllers designed for specific conditions. The hydrodynamic model plays an important role in the design of the controller for the inner loop. In addition, a gain scheduled controller is designed to validate a particular case of the fuzzy controller in the inner loop. Regarding the finishing of the vehicle to be fully operational, the improvements begin with a new driver for the lateral thrusters because they lacked backwards movement capability. Additionally, upgrades in the handling of the vehicle had to devised. In this respect, a wireless on/off system is presented to power the vehicle, and a WiFi connection is adapted to manipulate the software of the vehicle remotely. Furthermore, a study of the currents and power of the immersion system in order to reduce the power consumption is performed, and the hardware is improved with the inclusion of some commercial devices, like an IMU, CTD, and acoustic localization system. The software is improved in several aspects. First, some problems derived from previous works are debugged. The system is then restructured with a multithread development, which provides robustness and modularity. As the system needed an extension of the protocol communication for easy handling, a robust protocol communication is implemented with the possibility to execute scripts. Finally, the existing graphical user interface is simplified in order to provide only the information required by the operator. In order to improve the buoyancy of the vehicle, several foams are designed, adjusted to the geometry of the vehicle, and a ballast system is also included for fine adjustment. Finally, several tests in the laboratory, a swimming pool, a channel, and at sea are performed in order to check the performance of the vehicle. Results show a correct behavior of hardware and software, and also validate the performance of the controllers designed for autonomous navigation.Esta tesis aborda el desarrollo de un vehículo submarino existente para la navegación autónoma. El vehículo fue concebido para navegar sobre la superficie del mar siguiendo ciertos puntos preestablecidos, y hacer inmersiones verticales con el fin de obtener un perfil de una columna de agua. Los objetivos principales de la tesis son la mejora del hardware y el software del vehículo con el fin de que sea plenamente operativo, y el diseño e implementación de técnicas de control para la navegación autónoma. El problema de la navegación autónoma se aborda primero con el cálculo de un modelo hidrodinámico en 3 grados de libertad. Un extenso estudio sobre la selección de los coeficientes se realizó usando un modelo linealizado. El cálculo de los coeficientes se obtuvo utilizando dos enfoques: primero un enfoque geométrico, y luego un enfoque basado en técnicas de mínimos cuadrados aplicados a los datos experimentales obtenidos durante las pruebas de mar. El método de mínimos cuadrados da resultados satisfactorios y las simulaciones se ajustan a los datos experimentales. El modelo hidrodinámico resultante se completa con las limitaciones físicas de los actuadores del vehículo. Resolver el problema de navegación autónoma requiere el diseño de controladores tanto para el lazo interno (dinámico) como el lazo exterior (cinemático). En este sentido se presentan varias soluciones basadas en controladores difusos TSK tipo 1 para el control de velocidad, control de guiñada, navegación "pure pursuit", y "path following". El controlador difuso se utiliza para gestionar diferentes controladores lineales diseñados para condiciones específicas, y el modelo hidrodinámico juega un papel importante en el diseño del controlador del lazo interno. Además, se diseñó un controlador tipo "gain scheduling" para validar un caso particular del controlador difuso. En cuanto a poner el vehículo completamente operativo, las mejoras comienzan con un nuevo controlador para los propulsores laterales pues éstos carecían del movimiento en reversa. Adicionalmente se realizaron varias mejoras respecto a la fácil manipulación del vehículo. En este sentido se implementó un sistema inalámbrico para el encendido y apagado del vehículo, y se adaptó una conexión WiFi para poder manipular el software remotamente. Luego, se realizó estudio de las corrientes y voltajes implicados en el sistema de inmersión con el fin de reducir el consumo de energía, y finalmente el hardware se mejora con la inclusión de algunos dispositivos comerciales como un IMU, CTD, y sistema de localización acústica. El software se mejora en varios aspectos. En primer lugar, algunos de los problemas derivados de desarrollos anteriores se depuran. A continuación, el sistema se reestructura con un desarrollo multi-hilo que proporciona robustez y modularidad. Debido a que el sistema necesitaba la extensión del protocolo de comunicación para un fácil manejo, se implementó un protocolo de comunicación robusto con la posibilidad de ejecutar scripts. Por último, se simplifica la interfaz gráfica de usuario existente con el fin de proporcionar solamente la información necesaria para el operador. Con el fin de mejorar la flotabilidad del vehículo, se diseñan varias espumas ajustadas a la geometría del vehículo, y también se incluye un sistema de lastre para un ajuste fino. Por último, se hicieron varias pruebas en laboratorio, piscina, un canal, y en el mar con el fin de comprobar el rendimiento del vehículo. Los resultados muestran un comportamiento correcto de hardware y software, y también validan el funcionamiento de los controladores diseñados para la navegación autónoma

Autonomous Systems for the Environmental Characterization of Lagoons

This chapter reviews the state of the art in robotics and autonomous systems (RAS) for monitoring the environmental characteristics of lagoons, as well as potential future uses of such technologies that could contribute to enhancing current monitoring programmes. Particular emphasis will be given to unmanned aerial vehicles (UAVs), autonomous under water vehicles (AUVs), remotely operated underwater vehicles (ROVs) and (semi-)autonomous boats. Recent technological advances in UAVs, AUVs and ROVs have demonstrated that high-resolution data (e.g. 0.4 cm imagery resolution) can be gathered when bespoke sensors are incorporated within these platforms. This in turn enables the accurate quantification of key metrics within lagoon environments, such as coral morphometries. For example, coral height and width can now be estimated remotely with errors below 12.6 and 14.7 cm, respectively. The chapter will explore how the use of such technologies in combination could improve the understanding of lagoon environments through increased knowledge of the spatial and temporal variations of parameters of interest. Within this context, both advantages and limitations of the proposed approaches will be highlighted and described from operational, logistical, and regulatory considerations. The chapter will be based on recent peer-reviewed research outputs obtained by the authors

Time of arrival estimation using fast Fourier transform overlap for underwater distance measurement

1070-1080This paper presents an underwater acoustic distance measurement system based on Fast Fourier Transform (FFT) overlap. The low-cost underwater communication device is developed to achieve the objective. The time-of-arrival (TOA) technique is used to estimate the distance between the transmitter and receiver. The TOA estimation is derived based on the intensity of the received signal with frequency of interest. The extraction of the signal from the receiver is performed by using digital signal processing algorithms. FFT is used to convert the receiving signal from time domain into frequency domain for extracting the information of signal (relevant frequency and amplitude). Hence, TOA estimation can be obtained from the frequency information using overlap transform processing. This enables the increase of the TOA measurement resolution with the overlap technique. Trilateration algorithm is also employed as to determine the relative position of underwater target based on distance measurement. This approach is tested on shallow underwater to estimate the position of target. The experimental results are presented to demonstrate its capabilities

Collision avoidance control for Unmanned Autonomous Vehicles (UAV): Recent advancements and future prospects

873-883The recent advances in collision avoidance technologies for unmanned vehicles such as UAVs, AUVs, AGVs, and USVs have greatly advanced the industry. Their lower cost and acceptability of high-risk missions have enabled the development of collision avoidance controllers for autonomous vehicles. These low-maintenance gadgets are also portable, need low maintenance, and enable continuous monitoring to occur near real-time. This may be said; however it would be incorrect, because collision avoidance controllers have been related with compromises that affect data dependability. Research on collision avoidance controls is quickly developing; therefore it is distributed throughout multiple papers, projects, and grey literature. This report critically reviews the recent relevant research on creating collision avoidance systems for autonomous vehicles. Typically, the assessment measures are dependent on the algorithm's use case and the platform's capabilities. The full evaluation of the benefits and drawbacks of the most prevalent approaches in the present state of the art is provided based on 7 metrics which are complexity, communication dependence, pre-mission planning, robustness, 3D compatibility, real-time performance and escape trajectories