Evolution of the autonomous surface craft AutoCat

Abstract

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...

Development of a New Long Duration Solar Powered Autonomous Surface Vehicle

“…Short duration ASV platforms are under development in academia, government, and industry. Recent ASV research and development in academia includes the work of the AUV Laboratory at MIT for the development of the AutoCat Autonomous Surface Craft which is being used for bathymetric mapping and experiments in networked vehicle operations [2]. The MIT Department of Ocean Engineering has also developed the Surface Craft for Undersea and Oceanographic Testing (SCOUT) for use as a low-cost testbed for AUV algorithm development [3].…”

Autonomous Surface Craft: prototypes and basic research issues

“…In order to increase the ASC size, endurance and sea keeping performances, a kayak platform was considered, converting a 3m long kayak hull to an ASC and testing it in the Charles River. The resulting design was robust enough for severe sea states, but was not stable enough in roll for the collection of bathymetric data [2]. Thus, a catamaran shape, able to provide enhanced roll stability, greater payload, and redundancy in hull floatation, was selected for ACES (Autonomous Coastal exploration System, developed in 1996-97 [1].…”

“…Performances achieved in radio controlled tests were satisfactory, except for the tendency to pitch up at high speed and lack of feedback sensor in the rudder system. Nevertheless developing a reliable starter and gear actuator for the gasoline outboard motor was considered too complex for reliable autonomous operations [2]. A modified version of the catamaran, characterised by a modular fiberglass plastic composite structure and hullhoused batteries, was tested from 1999 [2].…”

“…Nevertheless developing a reliable starter and gear actuator for the gasoline outboard motor was considered too complex for reliable autonomous operations [2]. A modified version of the catamaran, characterised by a modular fiberglass plastic composite structure and hullhoused batteries, was tested from 1999 [2]. Main changes were made to the power and propulsion systems adopting an electric trolley motor and heavy-duty gel cells.…”

“…• the family of autonomous vessels developed at MIT, consisting of the fishing trawler-like vehicle ARTEMIS, the catamarans ACES (Autonomous Coastal Exploration System) and AutoCat [1] [2], and the kayak SCOUT (Surface Craft for Oceanographic and Undersea Testing) [3]; • the autonomous vessels developed in Europe such as the Measuring Dolphin of the University of Rostock (Germany) [4], the catamaran Delfim [5] and the boat Caravela [6] developed by the DSOR lab of Lisbon IST-ISR, the autonomous catamarans Charlie of CNR-ISSIA Genova (Italy) [7], and Springer, under development at the University of Plymouth (UK) [8]; • the unmanned surface vessels developed for military purposes such as the testbed of the SSC San Diego [9], the QinetiQ Ltd SWIMS systems [10], and the Israeli Protector USV. Basic research issues will be examined in section III, starting from the definition and identification of practical ASC dynamics models, going to advanced methodologies for control, guidance and mission control.…”