Marine robotics
Underwater robots for observation, sampling and intervention
Compare tethered operations with free-swimming surveys and include sensing, depth limits and launch resources in the mission.
An underwater job begins with the evidence or material that must return from the water. A video survey, a georeferenced map and a physical sample need different equipment. Reaching the target depth is only one requirement.
Two useful reference systems are WHOI's Jason, operated through a cable connection from a ship, and Sentry, an autonomous survey vehicle. They illustrate different mission arrangements rather than a universal ranking of underwater robots. [1] [2]
A tether carries both capability and handling requirements
WHOI describes Jason and Medea as a two-body remotely operated system. Its reinforced fiber-optic cable supplies electrical power and commands, while imagery and data return to the ship. Pilots and scientists use those feeds during operations. Jason also has manipulator arms and equipment for collecting samples. [1]
The connection makes the support vessel and cable handling part of the system. A proposed inspection must account for access around the structure, the approved cable path and the crew's recovery procedures. A small vehicle's dimensions alone do not define the space needed for the operation.
For an intervention, identify the tool, contact point and evidence that the action completed. A camera inspection cannot be credited as a successful sample recovery without the corresponding collection equipment and record.
A free-swimming mission needs a data and recovery plan
Sentry is documented for seafloor mapping and photography, with onboard navigation and acoustic support. Its arrangement suits a different type of evidence collection from an operator-directed sampling sequence. The specialist AUV guide examines that survey workflow. [2]
Scroll sideways for all columns.
| Required output | Arrangement to examine | Remaining question |
|---|---|---|
| Live inspection of a structure | Tethered vehicle with suitable cameras or sonar | Can the crew reach the required viewpoints and manage the cable? |
| A physical sample | Vehicle with an appropriate manipulator and collection system | Can the sample be identified, retained and recovered? |
| A mapped area | Survey vehicle with a defined sensor and navigation setup | Which regions meet the required coverage and position quality? |
Depth and instrument compatibility must be checked together
A depth rating applies to a specified configuration. Include housings, connectors, sensors, tools and any modifications in the review. Do not assume that an accessory shares the base vehicle's rating.
A simplified pressure calculation illustrates the load. With an assumed water density of 1,025 kg/m³ and gravitational acceleration of 9.81 m/s², an extra 100 m of depth adds about 1.01 MPa of pressure relative to the surface. This is a hydrostatic teaching calculation. It is not a housing design, pressure-test procedure or permission to operate at a depth.
The operating team must use the manufacturer's limits and approved launch, recovery and pressure-equipment procedures. Pressure arithmetic alone does not validate a vehicle assembly.
Judge the record that comes back
Consider a hypothetical inspection with 40 required target views. The vehicle reaches 36, but only 30 records show the required detail with a traceable target identifier. Access coverage is 90%; usable evidence coverage is 75%.
Separate missing viewpoints from unusable images. The first may require another approach, while the second may require a different observation distance, lighting arrangement or sensing method. These are possibilities to investigate through controlled trials, not a diagnosis from the counts alone.
Retain original files, timestamps, target identifiers and navigation information. Without those links, even a sharp image can be difficult to place in the inspection report.
Include the operation above the water
A mission estimate should include preparation, launch, transit to the target, useful work, recovery and data review. Name the required support vessel or shore arrangement and the qualified people responsible for each stage.
For comparison, use accepted observations or recovered samples over the full operating period. Hours submerged and maximum depth are useful context, but neither defines how much of the requested work was completed.
Sources and scope
Sources were consulted for this revision. Manufacturer descriptions are identified in the text. Worked examples are illustrative calculations, not measurements from a TechniaHQRobot test.
- WHOI ROV Jason and Medea
Cable-supported power and data, shipboard operation and sample handling.
- WHOI AUV Sentry
A contrasting autonomous survey configuration. No shared success benchmark is implied.