The Difference Between ROVs and AUVs

Rachel Doornekamp | April 20th, 2021

What are ROVs and AUVs
What Are the Benefits of Submersibles?
Do ROVs and AUVs have Add-Ons?
Choosing Between ROVs and AUVs
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There's a beautiful, blue planet to explore, both above ground and underwater. In earlier times, the ocean's depth limited people's ability to explore the ocean. Unassisted, humans can't dive to profound depths, as the water's pressure and weight quickly become too much. The risk of physical injury to divers becomes more likely starting at depths around 40 meters.

That's where underwater research vehicles come into play. In the 1960s, scientists, including naval researchers, developed the first underwater vehicles. These include human-occupied vehicles (HOVs) and crewless vehicles, such as remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs). ROVs and AUVs have both revolutionized deepwater exploration while keeping human scientists and researchers safely above the surface. Learn more about the differences between ROVs and AUVs and when you might use one versus the other.

Defining ROVs and AUVs

ROVs and AUVs are both submersibles that can explore the depths of the ocean without a human on board. There are distinct differences between the two, though.

What Is an ROV?

An ROV is a submarine that a researcher operates from above the water's surface. An ROV remains attached to a controller by a tether. The tether allows the crew aboard the ship to reel in the ROV at the end of a day's exploration. It also limits how far from the research vessel the ROV can travel on its own.

The tether's length can vary, depending on the project and the ROV's depth rating. An ROV with a depth rating of 305 meters can connect to a 1,000-foot tether without issue. Along with having different depth ratings and tether lengths, ROVs vary in size and speed. The type of ROV that might be right for your project depends on your goals, what you want the robot to do and how deep you need to go into the ocean.

Once they are in the water, what can ROVs do? Plenty, as it turns out. It's not uncommon for a camera to connect to an ROV, giving the team on the ship above a view of the ocean depths. The ROV can send video and images to the surface, shining a light on the equipment conditions that might be underwater. If the ship is investigating hazardous materials that somehow made their way into the ocean, the ROV's video can provide a clear picture of what's going with those materials without a diver having to put themselves at risk.

You can also fit an ROV with attachments that allow it to pick up items from the ocean's surface, such as sediment. One such accessory lets the ROV collect water samples, while a claw add-on allows it to pick up rocks or other larger pieces of debris.

While some ROVs draw power from the ship itself, through the tether, others are battery-operated. The battery power allows for speedier deployment of an ROV. It also allows the ROV to remain in the water for several hours at a time.

Researcher Deploys Pivot ROV into Ocean Surface from Port

What Is an AUV?

While an ROV remains tethered to a ship and remotely operated by a person aboard, an autonomous underwater vehicle or AUV gets to roam the ocean somewhat freely. One way to think of an AUV is like an autonomous car. Before lowering an AUV into the ocean, researchers program it, telling it where to go and what to do. The AUV might collect data or capture images or video. After completing its assigned tasks, the AUV makes its way to a meeting point, where researchers on the ship bring it out of the water.

Generally speaking, AUVs are better suited for collecting data in the water than collecting physical objects or water samples. They are a bit like the set-and-it-forget tools of underwater research. Since they don't require a human operator, the crew aboard a ship can focus on other tasks and projects while the AUV is underwater, gathering data.

Though crew members program AUVs before lowering them into the water, some can change their programming or adapt their missions on the fly, based on the conditions they encounter in the water. Usually, an AUV has sensors that allow it to detect water temperature and other conditions. The AUV might change course or complete its mission sooner than expected, based on the information it collects.

What Are the Benefits of Submersibles? Capabilities and Strengths

Crewless underwater vehicles such as ROVs and AUVs allow you to explore the depths of the ocean, check on equipment and investigate hazards and concerns without sending a team of divers into the water. Each has different advantages and might be the right choice for your project, depending on its needs and scope. Take a closer look at each underwater vehicle's strengths and capabilities.

Benefits of ROVs

DTG3 Rov Used to Explore Underwater Shipwreck

Here are some of the benefits of using an ROV.

Remain tethered to ships: An ROV never wanders too far from its home base, as its tether keeps it connected to the ship. The tether allows the ship's operators to maintain full control over the ROV.
Send real-time data to ship: Through the tether connection, an ROV can send information and imaging it collects to the researchers on the ship in real time. The crew can then take action immediately, if needed, based on the data provided by the ROV.
Can work in populous areas: An ROV can operate in areas that are off-limits to AUVs, such as parts of the ocean where there might be a lot of other ship activity or other research activity. The real-time, tethered connection decreases the chances that interference will confuse the ROV or send it off course.
Not affected by strong currents: The tether helps an ROV stay on course, even in choppy water or when strong currents might pull it.
Real-time piloting: With a remotely controlled ROV, someone keeps an eye on it the whole time it's in the water. While the ROV itself is unmanned, having a person above the water operating it means there's more likely to be a quicker response to hazards or issues that might come up.
Keep crew members safe: ROVs let crew members stay on board the ship, where they are safe and dry. The underwater vehicle can easily perform the tasks a diver would usually carry out, such as gathering samples or collecting materials.

Advantages of AUVs

Consider these benefits of using an AUV. - Can go into shallow areas: An AUV can be small enough to make its way into areas that might be too shallow for a research ship to travel into. - Can dive more deeply than humans: On the flip side, an AUV can also dive more deeply into the ocean than a human diver can. Since the AUV doesn't stay tethered to a ship, it can often explore more freely than an ROV. - Can amplify data collection: An AUV is pre-programmed, meaning that crew members can lower it into the water at a determined point, and it will go off and complete its tasks without supervision. While the AUV is independently operating, the people aboard the ship can focus on other aspects of data collection or project specialties, allowing them to accomplish more in less time. - Follow a pre-programmed path: Researchers program the AUV's path before lowering it into the water, so researchers have a fair idea of what the AUV will be doing underwater. It's also possible for an AUV to adjust its path if it detects something of interest or if there's an obstruction. - Battery-powered: Since AUVs are free of a tether, they always need to have a reliable power source, usually in the form of batteries. The battery life depends on the AUV's type and speed. If the AUV stays beneath the surface for an extended period, such as for more than a day, it might automatically decrease its speed to allow for a longer charge. - Keep crew members safe: Like ROVs, AUVs help crew members and researchers stay safe by eliminating or reducing the need for diving into the water.

Learn more about which underwater ROV is best for your application

Do ROVs and AUVs have Add-Ons?

Add-ons let you customize an underwater vehicle so that it best fits your needs. Generally speaking, add-ons are available for ROVs, but not for AUVs. Add-ons for ROVs let the vehicles complete tasks such as collecting samples or gathering materials from the ocean's bottom. Here are some available add-ons for Deep Trekker ROVs. - Water sampler: Water samplers collect water through a syringe and enable the ROV to bring a sample up to the surface for testing. - Claw attachment: A claw attachment lets an ROV pick up variously sized items without damaging them. - Caliper attachment: With a caliper attachment, the ROV can measure the size or thickness of objects in the water. - Cutter attachment: The cutter attachment allows the ROV to cut through tangled rope or wire that might be underwater. - Sediment sampler: A sediment sampler has two shovels that scoop up sand and other material from the ocean floor so that the ROV can bring it back to the surface. - Laser scaler: A laser scaler can work in tandem with a camera on the ROV, helping researchers get a clear idea of a pit's depth or the length of fish or other objects in the ocean.

Choosing Between ROVs and AUVs

Group of Researchers use DT3 ROV to Explore Clipperton island

Should you use an ROV or an AUV for your next project? The answer depends on multiple factors, from the project's overall scope to its budget. An AUV might make more sense for some underwater research projects, while an ROV is better suited for others. It could also be the case that an AUV is better for one part of your project, and an ROV is the clear choice for another component. Here are a few aspects consider when choosing between an ROV or an AUV.

The project's goal: ROVs are better for some tasks and AUVs for others. If you need to gather materials from the water, such as sediment, rocks or other materials, an ROV with a water or sediment sampler attachment or a claw attachment is likely your better choice. An AUV is a smart option if you are taking photos or making a map of the ocean floor, but don't need to retrieve any physical materials from the water.
Size of the project: Your project's size and scope can influence whether an ROV or an AUV is the right call. If there are many moving parts in the project or you're working with a small crew, an AUV, which doesn't require a human controller, can make sense. The AUV can travel through the ocean independently, collecting data while you and your team focus on other aspects of the project. If you have the crew to spare, an ROV can be a smart choice, as it delivers data and information in real time.
Project location: AUVs don't work well everywhere. Interference from other ships can throw them off-course. There's also a higher risk of an AUV crashing into another ship or even another AUV in busy areas. Since they don't need to stay tethered to a ship, an AUV can struggle in a part of the water with strong currents. ROVs are often a better pick for crowded parts of the ocean or areas with strong currents, since humans remain in control of them.
Length of the project: ROVs and AUVs can stay in the water for extended periods, but an AUV might have a slightly longer battery life, depending on its power source and speed. If you need an underwater vehicle to stay submerged for more than a day, an AUV might be your best pick. The batteries on an ROV can typically last for up to eight hours.
The project's budget: While cost shouldn't be a primary concern when choosing between an ROV or AUV, it's something to keep in mind. ROVs tend to be more affordable than AUVs due to their smaller size. Customizable options also give you more control over the final price tag of an ROV compared to an AUV. If you don't need a particular attachment or add-on for an ROV, you can skip buying it.

Learn More About Deep Trekker ROVs Today

Deep Trekker ROVs are the right tool for a range of underwater exploration projects, including search and rescue, inspections and marine life research. Learn more about our ROVs and available add-ons and see how an ROV can help your project by requesting a quote today.