Chasing Currents: Onboard Depth Optimization for AUV Energy Savings

We present the development and testing of an onboard behavior designed to achieve energy efficient transits by an autonomous underwater vehicle (AUV). The behavior allows an AUV to measure a profile of ocean currents on its descent and choose a depth in real-time that minimizes its energy consumption per unit distance. The behavior is implemented onboard a REMUS 100 AUV using a back-seat driver and the Robot Operating System (ROS). Two new behavior specific processes are defined and integrated on top of a previously developed ROS/REMUS architecture. Finally we present results from a proof of concept field experiment conducted off the coast of San Diego, CA. The AUV demonstrates successful depth-seeking and saves energy by intelligent navigation of ocean currents with a strong vertical gradient.