Preface

Autonomous Underwater Vehicles (AUVs) are remarkable machines that revolutionized the process of gathering ocean data. Their major breakthroughs resulted from successful developments of complementary technologies to overcome the challenges associated with autonomous operation in harsh environments. This book brings together the work of many experts in several domains related to the design, development and deployment of AUVs.

During the last decades, AUVs have gone through notable developments. In the late eighties and early nineties, the first prototypes required a tremendous effort and ingenious engineering solutions to compensate for the technological limitations in terms of computational power, batteries, and navigation sensors. To deploy these expensive vehicles navigating autonomously in a very unforgiving environment, and expecting them to return safely was a true act of faith in engineering, a scaled version of the early efforts in space technology.

The initial developments continued steadily and, by the end of the last century, AUVs have gradually moved from the controlled academic environment into challenging operational scenarios, covering scientific, commercial and military applications. As the technology matured, many different solutions were effectively demonstrated, in various sizes and configurations, and a few evolved into commercial products.

Underwater robotics is a peculiar field of knowledge, bringing together specific complementary knowledge in mechanical and electrical engineering, and also in computer science. In the last decade, with the impressive improvements in computational power, battery technology, and miniaturization of electronic systems, AUVs became less cumbersome and more amenable to be used as test beds for new techniques for data processing. As smaller, lighter, and less expensive equipment became available, the access to operational vehicles was further facilitated and more and more prototypes became accessible for testing new algorithms and solutions. The geographic span of valuable scientific work with field results was extended to include a larger number of researchers, not only from leading scientific institutions but also from more modest laboratories in emerging countries. This has resulted in an exponential increase in AUV development and deployment, alone or in fleets, with arguably many thousands of hours of operations accumulated around the world, and corresponding amount of data. Autonomous Underwater Vehicles became a common tool for all communities involved in ocean sampling, and are now a mandatory asset for gathering detailed ocean data at very reasonable costs.

Most of the advances in AUV capabilities aimed at reaching new application scenarios and decreasing the cost of ocean data collection, by reducing ship time and automating the process of data gathering with accurate geo location. Although this yielded significant improvements in efficiency, new approaches were also envisaged for a more productive utilization of this new tool. With the present capabilities, some novel paradigms are already being employed to further exploit the on board intelligence, by making decisions on line based on real time interpretation of sensor data. In many organizations, this ability is also being applied to allow the AUVs to conduct simple intervention tasks.

The design of Autonomous Underwater Vehicles is governed by a complex tradeoff between the critical requirements of the planned missions, and the main constraints on fabrication, assembly and operational logistics. Contrary to the early tendency to develop general purpose vehicles, the current pursuit of efficiency has pushed the concept of specific vehicles for specific tasks, frequently taking advantage of modular designs to accelerate the assembly time.

In the last years, there have been a great number of publications related to underwater robotics, not only in traditional engineering publications, but also in other fields where the robotic solutions are being used as a tool to validate scientific knowledge. There are also numerous conferences held each year, addressing all aspects of AUV development and usage. Both have served to report the major breakthroughs and constitute a foremost source of reference literature. This book collects a set of self contained chapters, covering different aspects of AUV technology and applications in more detail than is commonly found in journal and conference papers. The progress conveyed in these chapters is inspiring, providing glimpses into what might be the future for vehicle technology and applications.

> **Nuno A. Cruz** INESC Porto - Institute for Systems and Computer Engineering of Porto Portugal

**Part 1** 

**Vehicle Design** 

**0**

**1**

**Development of a Vectored Water-Jet-Based**

The applications of underwater vehicles have shown a dramatic increase in recent years, such as, mines clearing operation, feature tracking, cable or pipeline tracking and deep ocean exploration. According to different applications, the mechanical and electrical configuration and shape of an underwater vehicle are different. For instance, manipulators are necessary when doing mines clearing operation or some other tasks which need to deal with environment. If an underwater vehicle is used for underwater environment detection or observation, it is better to make this vehicle smaller and flexible in motion that it can go to smaller space easily. If the vehicle needs high speed moving in the water then a streamline

Different structures with different size of underwater vehicles are developed. Most of these underwater vehicles are torpedo-like with streamline bodies, like (Sangekar et al., 2009). And there are some small size AUVs like (Allen et al., 2002) and (Madhan et al., 2006). And also there are some other AUVs adopt different body shape, such as (Antonelli & Chiaverini, 2002). Meanwhile, the propulsion system is one of the critical facts for the performance of underwater vehicles, because it is the basis of control layers of the whole system. Propulsion devices have variable forms, for instance, paddle wheel, poles, magneto hydrodynamic drive,

Paddle wheel thrusters are the most common and traditional propulsion methods for underwater vehicles. Usually, there are at least two thrusters installed on one underwater vehicle, one for horizontal motion and the other for vertical motion. The disadvantages of paddle wheel thrusters are obvious, for example, it is easy to disturb the water around the underwater vehicles. Meanwhile, the more the paddle wheel thrusters are used, the weight,

The steering strategies of traditional underwater vehicles are changing the angular of rudders or using differential propulsive forces of two or more than two thrusters. Of course, there are vectored propellers being used on underwater vehicles. Reference (Cavallo et al., 2004) and (Le Page & Holappa, 2002a) present underwater vehicles with vectored thrusters. Reference (Duchemin et al., 2007) proposes multi-channel hall-effect thrusters which involves vector propel and vector composition. Reference (Le Page & Holappa, 2002b) proposes an autonomous underwater vehicle equipped with a vectored thruster. At the same time, the design of vectoring thrusters used on aircrafts is also an example of vectored propulsion

**1. Introduction**

body is required.

sails and oars.

noise and energy consumption increases.

system (Kowal, 2002), (Beal, 2004) and (Lazic & Ristanovic, 2007).

**Spherical Underwater Vehicle**

Shuxiang Guo and Xichuan Lin

*Kagawa University*

*Japan*
