A computer simulation study of station keeping by an autonomous submersible using bottom-tracking sonar

Abstract

For an Autonomous Underwater Vehicle to complete many operational missions, it must have the ability to maintain its position relative to the ocean floor. Maintaining station requires that the AUV be able to determine the direction and the distance displaced during a small time interval. Knowing the direction and distance traveled in a measured amount of time, the magnitude and direction of the ocean current can be calculated. Once this ocean current information is known, the AUV speed and direction can be properly adjusted to directly offset the ocean current forces. This thesis will attempt to determine, by computer simulation, if the first problem of AUV station keeping, vehicle movement direction and distance detection can be performed using bottom-tracking sonar as the AUV's only sensor. Both the problems of performing and storing successive synthetic sonar images and of determining AUV motion using frame to frame correlation of these images are investigated.