  In this paper, we seek to evaluate the effectiveness of a novel
forward-looking sonar system with a limited number of beams for collision
avoidance for small autonomous underwater vehicles (AUVs). We present a
collision avoidance strategy specifically designed for a novel forward-looking
sonar system based on posterior expected loss, explicitly coupling the obstacle
detection, collision avoidance, and planning. We demonstrate the strategy with
field trials using the 690 AUV, built by the Center for Marine Autonomy and
Robotics at Virginia Tech, and verify the forward-looking sonar system using a
prototype sonar with nine beams. Post-processed simulations are performed while
changing parameters in the sensitivity of the system to demonstrate the
trade-off between the detection and false alarm rates.
