Unmanned vehicles operating in the maritime domain can be grouped into three main categories: Autonomous Underwater Vehicles (AUVs), Remotely Operated Vehicles (ROVs), and Unmanned Surface Vehicles (USVs). Each vehicle type offers unique capabilities which support a wide range of commercial applications. 

AUVs function without the direct supervision of a human controller and generally offer extended endurance for long-term missions like surveys of marine life and pipelines, seafloor mapping, oceanographic data collection, etc. AUVs achieve this extended endurance by using a simplistic, hydrodynamically efficient design, like a torpedo, while also integrating advanced energy/propulsion systems. An example of this design is shown in figure 1 with the New Generation REMUS 100 from AUVSI member Hydroid Inc. The deployment of AUVs has provided tremendous cost savings for the industry and in many instances is providing data which may be otherwise unobtainable.

Figure 1: the New Generation REMUS 100 manufactured by AUVSI member Hydroid Inc. 

Counter to the AUV, ROVs are reliant on their human operator(s) to function. ROVs are connected to the surface by an umbilical cable that provides direct control over the vehicle’s movement and any attached payloads. This umbilical can also provide power from a supply on the surface and thus most ROVs can operate underwater indefinitely. ROVs offer high stability underwater and as such can be used for close-range inspection or intervention tasks like maintenance and assessments of pipelines, oil rigs, and other marine infrastructure. Another benefit of ROVs lies in the ability to operate in extreme environments that would be dangerous or unreachable for their human diver counterparts. Other examples of commercial applications for ROVs include cable intervention/burial, ship hull inspection/cleaning, trenching, dredging, wreck inspection/salvage, etc. Displayed in figure 2 is an affordable high-performance ROV developed by AUVSI member Blue Robotics for inspections, research, and exploration.

Figure 2: the BlueROV2 manufactured by AUVSI member Blue Robotics

Of the three categories, USV technology varies the most in terms of size, performance and vehicle design. USVs are not restricted by the size, weight and power limitations which AUVs must balance to achieve extended endurance. They are also free from the tether restrictions posed by ROVs. USVs can be fitted with solar cells, fuel cells, large battery systems, wind/wave-extracted energy systems, air-breathing combustion engines or some combination of these technologies to deliver mission lengths of months or even years. An innovative design from AUVSI member Boeing, the Wave Glider SV3 (figure 3) harnesses both wave and solar energy to operate for years at sea. USVs integrate radio or satellite links to provide connectivity over vast distances and many integrate some level of autonomy to allow the vehicle to complete its mission with minimal human supervision. These types of vehicles provide benefits for an array of applications like hydrographic surveys, port/harbor patrol, marine construction support, fishery monitoring, etc.

Figure 3: The Wave Glider SV3 manufactured by AUVSI member Boeing.

With continued advancement in unmanned vehicle technologies come exciting new concepts that push the envelope of what these systems can accomplish. Some of these concepts incorporate a hybrid approach from two of the above-mentioned categories to create a system which captures the strengths of both technologies. For example, Houston Mechatronics is developing the Aquanaut (figure 4) which can transform from a compact AUV for seabed mapping or structure inspections into a dual-armed ROV for intervention and manipulation tasks. Other concepts include the combination of multiple unmanned maritime vehicles into a system – for example the deployment of AUVs/ROVs from a surrogate USV.

Figure 4: Houston Mechatronic's Aquanaut. 

 Investigation of key data points

Using AUVSI’s Unmanned Systems & Robotics Database, we will investigate some key data points associated with unmanned maritime vehicles (UMVs) for commercial applications. 

Where are commercial UMVs manufactured? The data set captures information on over 500 unique vehicle models manufactured in 29 different countries worldwide. The United States is at the forefront in development of this technology with more than double the number of unique vehicle models relative to their closest competitor in the United Kingdom. As a continent, Europe pulls ahead of North America in this regard with Asia coming in a distant third place as developments in this region are recently starting to ramp up (figure 5 / figure 6).

Figure 5: UMV models by country

Figure 6: UMV models by continental location of primary manufacturer's HQ

How deep can commercial UMVs operate? The average max depth of UMVs in the database is approximately 4,900 feet. Given the median max depth from the data set is only 2,300 feet, this value is heavily weighted by some vehicles having reported max depths of over 20,000 feet. The plot in figure 7 shows the max depth distribution separated by vehicle type.

Figure 7: Max depth of commercial UMVs

How long can commercial UMVs operate? The median endurance for commercial UMVs is 12 hours while the average is skewed to over 200 hours given the 10 vehicle models (five USV models and five UUV models) with endurances of more than 60 days. Figure 8 shows the distribution of endurance across the three vehicle types, excluding vehicles with an endurance of more than seven days. Of course, this graph also excludes those vehicles with unlimited endurance through the use of external power supplies or renewable energy resources.

Figure 8: Endurance of commercial UMVs (limited to models with less than seven days' endurance)

How much do commercial UMVs weigh? The median weight of commercial UMVs is 270 pounds, with the smallest USV weighing just over three pounds and the largest vehicle — used for trenching operations — weighing more than 180,000 pounds. The portion of vehicles falling into a given weight range have been separated by category in figure 8. Vehicles weighing between 100 to 1,000 pounds represent the largest percentage of UMVs.

Figure 9: The weight ranges of commercial UMVs

Commercial UMVs represent an extensive range of technologies from small, short-range platforms to vehicles that can transit vast swaths of ocean. With continued advancements in energy/propulsion systems, sensors, autonomy/control techniques, communication systems, materials science, and other applied sciences, UMVs will further improve efficiency, safety, and open new possibilities for operators in commercial maritime applications.