Obstacle avoidance based on pitch angle- depth control and forward looking sonar for an autonomous underwater vehicle

This study includes obstacle avoidance plan based on controlling the pitch angle – depth and the use of forward looking sonar for an Autonomous underwater vehicle (AUV). The forward looking sonar with vertical and horizontal scanning capability provides a measure of the distance and height of the obstacle to the guidance system. The guidance system determine the degree of vertical overlap of the obstacle with the sonar view window and using the dynamics of the device in the vertical channel, convert the angle of overlap to the rate of change of depth and thus the safe reference depth to avoid collision. Performing the optimal depth maneuver on the vertical plane leads to significant reduction in deviation from the main path and distance compared to conventional methods for bypassing the obstacle in the horizontal plane. This feature along with simple math makes it more attractive to use for devices with fast-dynamic. The results of the implementation in the context of a six-degree-of freedom model of an AUV indicate the proper performance of the proposed method of obstacle avoidance.