Robots in our oceans are becoming a normality. Not only are they easy to deploy, but they’re significantly more affordable than multi-million dollar moorings which also require expensive ships to position. The first AUV was developed at the Applied Physics Laboratory at the University of Washington circa 1957 by Stan Murphy, Bob Francois and later on, Terry Ewart. They were primarily made for the U.S. military and labeled “Special Purpose Underwater Research Vehicle”, or SPURV. They were employed to study diffusion, acoustic transmission, and submarine wakes. Today, the majority of ocean drones are used for environmental monitoring.
Ocean Robot Propulsion System
The most common AUV propulsion system is a combination of an electric motor with rechargeable batteries. The autonomy of the vehicle depends on the battery capacity and the efficiency of the motor. In order to conduct longer surveys and cover longer distances engineers turned to self powered systems using waves and buoyancy as propulsion to help extend the ranges of autonomous vehicles.
Underwater gliders for example, do not directly propel themselves. They change their buoyancy and trim, repeatedly sinking and ascending; hydrofoil wings convert this up-and-down motion to forward motion. Because of their low speed and low power electronics, the energy required to cycle trim states is far less than for regular AUVs.
Rutgers Slocum Glider is named after Joshua Slocum, the first man to single-handedly sail around the world. Consequently, in 2009 Rutgers launched “The Scarlet Knight” glider from New Jersey and succeeded in the first transatlantic crossing achieved by an ocean robot. Today Rutgers is working on launching its 2014 Challenger mission where 16 global-class autonomous underwater gliders will be flown on coordinated flights covering 128,000 kilometers across the five ocean basins.
Liquid Robotics engineers chose wave power to propel their surface glider. Attached to what seem to be a surfboard is a series of pivoting hydrofoils that respond to wave movements and propel the robot. In November of 2011 Liquid Robotics launched PacX, the longest ocean crossing by robots. “During their journey, the Wave Gliders traveled from California to Hawaii, and then split into pairs where one pair continued to Australia where “Papa Mau” arrived in November of 2012 and “Benjamin” arrived in February 2013, setting world records. The Japan-bound Wave Gliders encountered difficulties along the way, and their journey was postponed.”
Ocean Robot Challenges
Deep space and the ocean have something in common in that they are both extremely hostile environments; temperature and pressure in these environments challenge every part of a robot’s functionality. Ocean robots also contend with something space robots don’t: potential attacks by curious predators like sharks. Another challenge is presented when venturing into the polar oceans to collect Arctic and Antarctic data. For gliders and Argo floats the main issue is finding a break in the ice to transmit their data to a satellite. For autonomous vehicles on the surface, there is the potential of getting stuck in a sea of ice. That is of course just a fraction of the technical challenges endured by sensitive electronics surrounded by salt water.
Ocean Robot Data in Marinexplore
As technology evolves, prices fall, and environmental challenges are surmounted, the amount of robots in the ocean will increase exponentially. There are over 2 million sensors currently deployed in the Earth’s oceans, capturing thousands of public and private data streams. This growth in ocean-borne devices is driving up the volume of available ocean data and transforming the $80B data acquisition market. At Marinexplore.org, we’re currently tracking over 37,000 in-situ platforms, including buoys, marine mammals, research ships and autonomous robots. For a glimpse into the ocean data these devices are collecting, check out this Data Studio bookmark for Argo floats, gliders, and wave gliders. Also join us in the discussion on Marinexplore.org about the future for ocean borne devices, open source and commercial.