Design and Implementation of a Collision Avoidance System for the NPS AutonomousUnderwater Vehicle (AUV II) Utilizing Ultrasonic Sensors

摘要

The recognition of underwater objects and obstacles by sonar has been explored inmany 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 Vehicles (AUV) by applying regression analysis and geometric interpretation of sonar range data obtained from a low-cost, low-resolution, fixed-beam sonar. The algorithm utilized by this method first develops a least-squares 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. The 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.