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The Wave Glider TM wave-powered unmanned maritime vehicle represents a novel and unique approach to persistent ocean presence. Wave Glider is a hybrid seasurface and underwater vehicle in that it is comprised of a submerged "glider" attached via a tether to a surface float. The Wave Glider vehicle is propelled by the purely mechanical conversion of ocean wave energy into forward thrust, independent of wave direction. In this paper, we provide an overview of the design of this new platform and present results from the engineering sea trials conducted with several prototype and production versions of the vehicle. In addition to the Wave Glider technology, we present results from ongoing scientific demonstration programs. Results from test deployments of a conductivity-temperature-depth sensor and its applicability to oceanography are discussed.

At the MIT Sea Grant College Program, Autonomous Surface Craft (ASCs) have been under development since 1993. These systems have been designed for various missions and have demonstrated success in three separate iterations. The current goal of ASC research at MIT isto develop an easily deployed system that can serve as a tool for educational use, as a precision survey platform, and as a communications and navigation link to an AUV. In the past, this goal has been hampered by limitations in the mechanical design of the current system.Since September 1998 significant improvements have been made to the design of the current ASC. New power, propulsion, and control systems have been installed. These improve the performance of the vehicle and significantly reduce the mechanical and electronic failures that troubled the previous system. In addition, structural modifications have been made to make deployments and operations easier. These design improvements promise to make the ASC a more useful tool for, and provide greater service to, the Autonomous Underwater Vehicles Laboratory at MIT. This paper will briefly present the history of ASC development at MIT. It will then document the design changes made to the current vehicle. The problems experienced with the old designs will be identified and the improvements represented by the new systems will be explained. The paper will conclude with a brief discussion of the next mission for the ASC.I -ASCs at MIT Sea Grant derivative (PD) control system to implement simple heading control. These first steps yielded an ASC with limited autonomy but provided a valuable proof of concept [ 11.Follow on work added a Differential GPS (DGPS) receiver to enhance the navigation system of ARTEMIS. This facilitated the development of a heading constrained waypoint following controller based on Fuzzy Logic. A depth sounder was added and ARTEMIS executed waypoint-defined surveys to generate bathymetric maps of the Charles River in Cambridge, MA. The addition of a radio modem allowed these bathymetric maps to be generated in real time and provided human supervisory control of the ASC [2]. Upon completion of these experiments ARTEMIS was retired from active use. B. The Autonomous KayakOne of the primary shortcomings of the ASC ARTEMIS was its small size. This limited its endurance and seakeeping. The field operations of ARTEMIS were limited to the Charles River, a region of limited scientific interest. To produce an ASC with more useful capabilities a kayak platform was examined [3]. Upon completion of design studies a 3 m long kayak hull was obtained and converted into an ASC. A new propulsion system and actuator were installed, as were electronics similar to those used in ARTEMIS. This new vehicle underwent a series of trials on the Charles River. It was then fitted with acoustic tracking systems and used to follow a tagged fish [4]. Upon conclusion of these experiments this ASC was turned over to the MIT Ocean Engineering Teaching Lab for use in student research and education projects. A. The...