Unmanned surface vehicles: An overview of developments and challenges

This paper describes a concept for a collision avoidance system for ships, which is based on model predictive control. A finite set of alternative control behaviors are generated by varying two parameters: offsets to the guidance course angle commanded to the autopilot and changes to the propulsion command ranging from nominal speed to full reverse. Using simulated predictions of the trajectories of the obstacles and ship, compliance with the Convention on the International Regulations for Preventing Collisions at Sea and collision hazards associated with each of the alternative control behaviors are evaluated on a finite prediction horizon, and the optimal control behavior is selected. Robustness to sensing error, predicted obstacle behavior, and environmental conditions can be ensured by evaluating multiple scenarios for each control behavior. The method is conceptually and computationally simple and yet quite versatile as it can account for the dynamics of the ship, the dynamics of the steering and propulsion system, forces due to wind and ocean current, and any number of obstacles. Simulations show that the method is effective and can manage complex scenarios with multiple dynamic obstacles and uncertainty associated with sensors and predictions.

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Ship Collision Avoidance and COLREGS Compliance Using Simulation-Based Control Behavior Selection With Predictive Hazard Assessment

This paper describes planar motion modeling for an unmanned surface vehicle (USV), including a comparative evaluation of several experimentally identified models over a wide range of speeds and planing conditions. The modeling and identification objective is to determine a model that is sufficiently rich to enable effective model-based control design and trajectory optimization, sufficiently simple to allow parameter identification, and sufficiently general to describe a variety of hullforms and actuator configurations. We focus, however, on a specific platform: a modified rigid hull inflatable boat with automated throttle and steering. Analysis of experimental results for this vessel indicates that Nomoto's first-order steering model provides the best compromise between simplicity and fidelity at higher speeds. At low speeds, it is helpful to include a first-order lag model for sideslip. Accordingly, we adopt a multiple model approach in which the model structure and parameter values are scheduled based on the nominal forward speed. The speed-scheduled planar motion model may be used to generate dynamically feasible trajectories and to develop trajectory tracking control laws. The paper describes the development, analysis, and experimental implementation of two trajectory tracking control algorithms: a cascade of proportional-derivative controllers and a nonlinear controller obtained through backstepping. Experimental results indicate that the backstepping controller is much more effective at tracking trajectories with highly variable speed and course angle. © 2013 Wiley Periodicals, Inc.

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Modeling, Identification, and Control of an Unmanned Surface Vehicle

Autonomous underwater vehicles (AUVs) are submersible underwater vehicles controlled by onboard computers. AUV formation is a cooperative control which focuses on controlling multiple AUVs to move in a group while executing tasks. In contrast to a single AUV, multi-AUV formation represents higher efficiency and better stability for many applications, such as oil and gas industries, hydrographic surveys, and military missions, etc. To achieve better formation, there are several key factors, including AUV performance, formation control, and communication capability. However, most studies in the field of AUV formation mainly focus on formation control methods. We observe that the research of communication capability and AUV performance of multiple AUV formation is still in an early stage. It is beneficial to researchers to present a comprehensive survey of the state of the art of AUV formation research and development. In this paper, we study AUV, formation control, and underwater acoustic communication capability in detail. We propose a classification framework with three dimensions, including AUV performance, formation control, and communication capability. This framework provides a comprehensive classification method for future AUV formation research. It also can be used to compare different methods and help engineers choose suitable formation methods for various applications. Moreover, our survey discusses formation architecture with communication constraints and we identify some common misconceptions and questionable research for formation control related to communication.

A Survey of Autonomous Underwater Vehicle Formation: Performance, Formation Control, and Communication Capability

Swarm robotics is a promising approach for the coordination of large numbers of robots. While previous studies have shown that evolutionary robotics techniques can be applied to obtain robust and efficient self-organized behaviors for robot swarms, most studies have been conducted in simulation, and the few that have been conducted on real robots have been confined to laboratory environments. In this paper, we demonstrate for the first time a swarm robotics system with evolved control successfully operating in a real and uncontrolled environment. We evolve neural network-based controllers in simulation for canonical swarm robotics tasks, namely homing, dispersion, clustering, and monitoring. We then assess the performance of the controllers on a real swarm of up to ten aquatic surface robots. Our results show that the evolved controllers transfer successfully to real robots and achieve a performance similar to the performance obtained in simulation. We validate that the evolved controllers display key properties of swarm intelligence-based control, namely scalability, flexibility, and robustness on the real swarm. We conclude with a proof-of-concept experiment in which the swarm performs a complete environmental monitoring task by combining multiple evolved controllers.

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Evolution of Collective Behaviors for a Real Swarm of Aquatic Surface Robots.

To celebrate the 40th Anniversary of the Oceanic Engineering Society (OES) at the MTS/IEEE OCEANS 2008 Conference in Quebec City a series of review papers were requested from OES technical committee chairs. In response to that request this paper provides a review of the field of unmanned surface vehicles (USVs) and autonomous surface craft (ASCs). The paper discusses the enabling technologies that have allowed USVs to emerge as a viable platform for marine operations as well as the application areas where they offer value. The paper tracks developments in technology from early systems developed by the author in 1993 through the latest developments and demonstration programs. The future outlook for USV technology is also described.

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Unmanned surface vehicles, 15 years of development

In 2004 the US Navy transferred the USNS Capable (T-AGOS 16) to the National Oceanic and Atmospheric Administration (NOAA). The vessel has recently completed an extensive conversion effort to become the NOAA Ship Okeanos Explorer. NOAA's Office of Ocean Exploration and Research (OER) will use the vessel to conduct multi-disciplinary ocean exploration and research projects. OER's goal is to increase America's knowledge of the U.S. Exclusive Economic Zone and other areas of the roughly 95 percent of the underwater world not previously explored and largely unknown. As a new vessel dedicated to ocean exploration the Okeanos Explorer received significant upgrades and new equipment. This paper describes the major facets of the conversion. The Okeanos Explorer will be the first NOAA vessel to carry a dedicated remotely operated vehicle (ROV) and systems designed to connect the ship and ROV activities to shore via ldquotelepresence.rdquo The development and integration of these new technologies on the vessel is also described. The paper concludes with a discussion of how OER envisions these tools being employed in ocean exploration.

New tools for ocean exploration, equipping the NOAA Ship Okeanos Explorer

In response to an expression of interest by the U.S. Navy, ASTM International and the Association for Unmanned Vehicle Systems International (AUVSI) embarked upon the process of developing technical standards for unmanned undersea vehicles (UUVs.) In 2005 a formal committee was formed under ASTM's established and recognized standards development procedures. ASTM Committee F41 on Unmanned Vehicle Systems is working on the development of technical standards for autonomy, mission payloads, sensors, communications interfaces and data. These standards are initially intended to support the U.S. Navy Mission Reconfigurable UUV System (MRUUVS) program. They will be referenced in the MRUUVS request for proposals and ideally they will improve the eventual MRUUV system. This paper discusses the history of the standards development, the content of the standards which will go to ballot in June 2005 and the potential applicability of these standards to UUVs beyond the U.S. Navy's large diameter UUV programs.

Development of UUV Standards, an Emerging Trend

The National Oceanic and Atmospheric Agency (NOAA) is charged with a diverse set of missions. Many of which can be served by the appropriate application of new technologies, such as autonomous underwater vehicles (AUVs). To capitalize on the rapidly evolving AUV technology base, NOAA chartered a cross-agency working group to coordinate AUV activities in the agency. This team has compiled results from pilot programs and analyzed operational results to understand the value of AUVs in NOAA missions. A report entitled Applying AUVs to NOAA Goals: Current Status and Future Opportunities was submitted to NOAA senior leadership on June 1, 2006. This paper provides an overview of the NOAA AUV opportunities report. It discusses the role of AUVs in major NOAA strategic goal areas such as ecosystem research and management, commerce and transportation and climate. Significant pilot programs discussed include coast survey, fisheries science and ecosystem research applications. Technical and operational challenges are discussed and recommended steps for further integration of AUVs in NOAA are described.

J.E. Manley

Papers

Unmanned surface vehicles, 15 years of development

New tools for ocean exploration, equipping the NOAA Ship Okeanos Explorer

Development of UUV Standards, an Emerging Trend

NOAA's AUV Vision: Status and Opportunities