Vehicle types¶
Maritime robots differ mainly in where they operate (on or below the surface), how they get power and communication (tether or not), and how they move (propellers, thrusters, buoyancy, or sail). Each choice changes the software.
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Surface vehicles (ASV / USV)
Work on the surface: survey, monitoring, logistics, and relay for underwater vehicles. GNSS, radio, and solar power are available. Usually 2 or 3 controlled DOF (surge and yaw, sometimes sway).
Software focus: GNSS and heading fusion, obstacle detection (radar, lidar, AIS, cameras), COLREGs, waves.
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Torpedo AUVs
Untethered, streamlined, efficient for long survey lines. Usually underactuated: one propeller plus fins or a vectored thruster.
Software focus: DVL and INS dead reckoning, depth and altitude control, mission autonomy, acoustic communication.
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Hovering AUVs and ROVs
Many thrusters for 4 to 6 controlled DOF; hold station for inspection and intervention. ROVs are tethered and piloted; hovering AUVs are free.
Software focus: thrust allocation, station keeping, perception near structures, manipulation, teleoperation.
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Underwater gliders
Change buoyancy to move in a sawtooth pattern with wings, with no propeller. Slow, but missions last weeks to months.
Software focus: energy-aware planning, sparse communication at each surfacing, dead reckoning with unknown currents.
Comparison¶
| ASV / USV | Torpedo AUV | Hovering AUV | ROV | Glider | |
|---|---|---|---|---|---|
| Tether | No | No | No | Yes | No |
| Power | Battery, solar, fuel | Battery | Battery | Through the tether | Battery |
| Endurance | Hours to months | Hours to days | Hours | As long as the support vessel stays | Weeks to months |
| Controlled DOF | 2-3 | 3-4 (surge, heading, depth or pitch) | 4-6 | 4-6 | Pitch, heading, buoyancy |
| Position source | GNSS | DVL + INS; GNSS at surface; acoustic | DVL + INS; acoustic; vision | Topside USBL; DVL | Dead reckoning; GNSS at surface |
| Communication | RF, cellular, satellite | Acoustic; RF and satellite at surface | Acoustic | Tether (high bandwidth) | Satellite at surface |
| Typical ROS 2 stacks | Project11, VRX models, Nav2 | SMaRC 2, MVP | Blue, MVP | Blue, Orca, ArduSub | Mostly vendor software |
Specialized platforms¶
- Autonomous sailboats use wind for propulsion and need sail and rudder control with wind-aware routing. See the rs750 simulation in Simulation.
- Intervention vehicles carry one or two manipulators for valve turning, sampling, or tool use. Software: MoveIt 2 for arm planning, whole-body or impedance control (auv_controllers), and vehicle station keeping.
- Hybrid ROV / AUV (HROV) vehicles switch between tethered piloting and free autonomous operation.
- Wave-powered and energy-harvesting platforms convert wave motion into propulsion or electrical power; see MBARI WEC in Simulation.
- Bio-inspired vehicles use fins, flippers, or pulsed jets; mostly research platforms.
What it means for your software¶
| If your vehicle is... | Then you need... |
|---|---|
| Underactuated (most ASVs, torpedo AUVs) | Guidance that controls course and speed, not sway; LOS path following |
| Over-actuated (most ROVs) | Thrust allocation with saturation handling |
| Untethered and submerged | Full onboard autonomy, safe failsafes, and acoustic or no communication |
| Tethered | Topside processing is possible; manage tether drag in control |
| Long-endurance | Energy-aware mission planning and robust recovery from faults |