Thriving Under Pressure: Diving into the Role of Pressure and Depth Sensors in ROVs

Posted on 17/11/2023 by EmilyNewton in Underwater

ROV pressure sensors and depth sensors are critical for underwater safety and navigation. Remotely piloting a robot is much more complicated underwater than on land. Depth sensors resolve this issue. What role do pressure and depth sensors play in ROV navigation, and how do these sensors work?

The Challenges of Underwater Navigation

ROV depth sensors and pressure sensors are necessary due to the unique challenges of underwater navigation. On land, a robot can find its way around using cameras, distance sensors and light sensors. Usually, it only needs to move horizontally across the ground. Things are more complex underwater, though.

Underwater ROVs move in three dimensions rather than just two. They can "swim" along the x, y and z-axis, which makes navigation more complex. Now, the robot must know how far it is from the surface.

On land, the robot might be able to determine its height with a camera or distance sensor. However, underwater ROVs usually can't see the surface, let alone the ocean floor. Plus, some regions of the ocean can be extremely dark.

Light levels begin to decrease once the robot gets about 650 feet below the surface. By about 3,200 feet below the surface, there is no sunlight at all, so the ROV has to determine its depth without relying on visual aids. The best way to accomplish this is by measuring the surrounding water pressure.

How ROV Pressure Sensors and Depth Sensors Help

Underwater ROVs use a variety of sensors and equipment to navigate and collect data. Pressure sensors are one of the most critical elements of the ROV, though. They allow robots to determine how far they are from the water's surface by measuring water pressure.

How Underwater Pressure Sensors Work

A basic pressure sensor measures force to determine applied pressure. For example, a pressure sensor might consist of a small canister with some air trapped inside. As the sensor gets deeper underwater, the water pressure will increase and compress the air. The sensor can measure the force compressing the air, known as hydrostatic pressure.

In any underwater environment, hydrostatic pressure increases as depth from the surface increases. By measuring hydrostatic pressure, a sensor can determine underwater depth. This fundamental principle allows all kinds of devices to measure depth, from advanced ROVs to everyday diving watches.

Using Pressure Sensors for ROV Safety

ROVs use pressure sensors for navigation and safety. One of the most important qualities of any ROV is its depth rating — the maximum underwater depth a robot can safely descend to. ROVs can only handle so much pressure before they begin to lose structural integrity.

At a low enough depth, the water pressure can crush a robot like an empty soda can. ROVs need precise pressure sensors to monitor depth and prevent this from happening.

The depth rating of an ROV typically depends on its intended purpose. For instance, a commercial diving robot won't need to travel as deep as a scientific research ROV. Generally, ROVs get more expensive the higher the depth rating due to the engineering complexity of building a robot with extreme durability.

ROV depth sensors themselves also have depth ratings. Usually, sensor depth ratings have more to do with precision than durability, though. For example, the Blue Robotics Bar02 sensor is only rated for a 10-meter depth but measures that narrow depth with ultra-high accuracy.

How Pressure Sensors Assist Underwater Navigation

Pressure sensors are also crucial for navigation. They usually work with other navigation technology, such as sonar imaging. Sonar is best known as the sound-based ability dolphins use. It works by emitting sound waves and measuring how they bounce off nearby objects.

ROVs often use sonar imaging to identify things underwater and avoid crashing into obstacles. The person remotely controlling the ROV can also use sonar images to get an idea of what the robot is "seeing." This is especially helpful if the ROV doesn't have cameras.

The robot's operator uses the pressure sensor to ensure their ROV is in the right location vertically. Once there, they take a look around with sonar.

ROV Depth Sensor Use Cases

To understand the role of ROV depth sensors, look at them in action in a few use cases. There are countless applications for ROVs, but exploration, search and rescue, and military operations are among the most prominent.

Deep Sea Exploration

Deep sea exploration is one of the most exciting use cases for ROV depth sensors. Robots are ideal for exploring the lowest reaches of the ocean because they can handle extreme pressures and temperatures while a human diver cannot. Engineers and explorers work together to use underwater ROVs to make discoveries in the deep sea.

For example, the National Oceanic and Atmospheric Administration (NOAA) uses ROVs for mapping, exploration and research. NOAA scientists have even discovered new species of aquatic life with underwater ROVs!

In exploration scenarios like this, depth sensors tell scientists where their ROV was when they found a creature or plant. The devices also ensure they pilot the ROV within its safe depth range.

Underwater Search and Rescue

ROV depth sensors are critical in underwater search and rescue operations. Search and rescue is extremely complicated in the water due to the lack of visibility and air. The search teams need to either go SCUBA diving or use robots. At extreme depths, even SCUBA diving isn't an option.

Search and rescue ROVs use depth sensors to navigate and report mission-critical data. For example, the ROV might descend 50 feet below the surface and use sonar to discover part of a sunken boat. The ROV's depth data is vital for helping human search teams locate and recover that piece of evidence.

Military ROV Operations

Military operations need to be precise, so accurate depth data is crucial. There are countless applications for military ROVs, from reconnaissance to research. Depth data tells military personnel where potentially dangerous obstacles are underwater. It's also vital for maneuvering and ensuring ROVs don't exceed a certain depth.

Military operations are also more likely to require groups of ROVs. In this case, depth data is necessary for accurate positioning. It helps ensure the robots don't accidentally crash into one another underwater.

The Amazing Capabilities of ROV Depth Sensors

ROV pressure sensors and depth sensors provide invaluable data for safety and navigation. A depth sensor measures the water pressure on an ROV to determine how far it is from the water's surface. There are many applications for this information in engineering, exploration, search and rescue, and military use cases. Thanks to depth sensors, ROV pilots can accurately monitor how deep they are in the ocean, leading to more efficient, user-friendly ROV operation.

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