Development of a Versatile Test-Bed "Twin-Burger" toward Realization of Intelligent Behaviors of Autonomous Underwater Vehicles


Twin-Burger


Teruo Fujii, Tamaki Ura ,Yoji Kuroda, Hiroyuki Chiba, Yoshiaki Nose, and Koji Aramaki

Institute of Industrial Science, University of Tokyo
7-22-1 Roppongi Minato-ku Tokyo, 106, JAPAN

Abstract

A versatile test-bed named "The Twin-Burger" was developed at the Institute of Industrial Science, the University of Tokyo to establish the techniques which realize intelligent behaviors of autonomous underwater vehicles (AUVs). Construction of the vehicle was completed and it was launched in November 1992. This paper describes hardware and software systems of the vehicle in detail. Motion of the vehicle is controlled by sliding controllers based on simplified equations of motion which are derived from system identification experiments. Several tank tests were carried out to investigate the controllers' performance. It is shown that the vehicle successfully cruises along a commanded path as a sequence of control actions which are generated by the sliding controllers.

I. INTRODUCTION

In AUV (Autonomous Underwater Vehicle) research fields, development of control softwares which enables the vehicle to survive and accomplish complex tasks in unstructured environments is one of the most important subjects. The authors have been studying on intelligent motion control systems for a cruising type AUV called "PTEROA150" using neural network techniques[1-3]. Through this experience, it appears that the softwares should be verified and improved not only in a simulated environment but also in real environments because there are many unexpected problems related to vehicle's hardwares and environmental conditions.

In order to investigate more general approaches toward realization of intelligent behaviors of AUVs, such as software architectures, theories for distributed intelligence, etc., a project to build a versatile test-bed vehicle named "The Twin-Burger" was planned at the Institute of Industrial Science (IIS), the University of Tokyo in 1991[4]. The Twin-Burger was designed to have necessary functions for complex tasks including multi-vehicle and diver-vehicle cooperative works, and to ensure convenient and reliable operation in experiments.
Construction of the vehicle was completed and it was launched in November 1992. This paper describes the configuration, the onboard instruments, and the software system of the vehicle in detail.
A method of motion control should be considered so that the vehicle behaves according to the given mission. Control problems of underwater vehicles often involves difficulties caused by their nonlinear dynamics especially when they moves at low speed. Moreover, they may be exposed to unknown disturbances in experimental fields. Sliding control is one of the established control methods for underwater vehicles[5-7] which is capable of direct handling of nonlinear dynamics and compensating unknown disturbances. Focusing on these advantages, a sliding control method, which is developed by Yoerger and Slotine[8], is applied to the Twin-Burger. The controllers for the vehicle are designed on the basis of the results of system identification experiments. Path following tests are carried out in a tank to investigate implemented controllers' performance and to establish the Twin-Burger's ability to cruise along commanded paths.

Modified 970304.1735