Design and implementation of a collision avoidance system for the NPS Autonomous Underwater Vehicle (AUV II) utilizing ultrasonic sensors.

The recognition of underwater objects and obstacles by sonar has been explored in many forms, particularly through the use of high-resolution imaging sonar systems. This work explores a method of providing real-time obstacle avoidance and navigational position updating for an Autonomous Underwater Vehicle (AUV) by applying regression analysis and geometric interpretation to sonar range data obtained from a low-cost, lowresolution, fixed-beam sonar. The algorithm utilized by this method first develops a leastsquares fit for sonar range data in a 2-D manner. The parameters developed by this method are then compared to an environmental model for position identification. If no match is achieved, then by applying the known geometry of the acoustic signal, an estimate for a 3- D surface is derived. This derived 3-D surface is then added to the environmental model to enable accurate path planning and post-mission analysis information. This method is currently implemented on an operational AUV operating in a well-defined orthogonal environment at NPS. The paper also discusses the simulation of the sonar systems using a ray tracing technique in a real-time dynamic graphical simulation implemented on a Silicon Graphics IRIS workstation.http://archive.org/details/designimplementa00floyCommander, United States NavyApproved for public release; distribution is unlimited