# AKULA Robotics

> Build log, glossary, guides and roadmap for an open, self-buildable autonomous underwater vehicle. Free Control asset — no store.

## The Build Log

- [First wet test of the pressure hull](/log/first-wet-test/?format=md)
- [ARGUS-6: first ping in the test tank](/log/argus-6-first-ping/?format=md)
- [Why the main drive spins both ways](/log/contra-rotating-bench/?format=md)
- [The power budget is the mission](/log/power-budget-reality/?format=md)

## The Boat — glossary

- [Pressure Compensator](/the-boat/compensator/?format=md): Keeps oil-filled volumes at sea pressure so nothing gets crushed or sucked in.
- [Stability & Buoyancy Node (SBN)](/the-boat/stability-buoyancy-node/?format=md): The pneumatic system that makes the vehicle sink, rise, and hover by changing its weight in water.
- [Trim Pump](/the-boat/trim-pump/?format=md): Moves water fore-and-aft to keep the vehicle level.
- [Variable Ballast Tank](/the-boat/variable-ballast-tank/?format=md): The tank whose water content sets how heavy the vehicle is right now.
- [ABYSS-Link Acoustic Modem](/the-boat/abyss-link-acoustic-modem/?format=md): Talking through water with sound at 133–150 kHz — slow, but it works in the deep.
- [Blue-Fi Optical Modem](/the-boat/blue-fi-optical-modem/?format=md): High-speed data over blue light — fast, but only over short, clear-water spans.
- [DVB-T Video Broadcast](/the-boat/dvb-t-video-broadcast/?format=md): Broadcasting live video up to a surface buoy using off-the-shelf TV standards.
- [Hybrid Comm Node](/the-boat/hybrid-comm-node/?format=md): The surfaced link: LTE, LoRa, and satellite, plus the cockpit ground station.
- [Frame & Ring Stiffeners](/the-boat/frame-stiffeners/?format=md): Internal rings that brace the hull against buckling and carry mounting loads.
- [Penetrators & Seals](/the-boat/penetrators-seals/?format=md): Every wire and pipe that crosses the hull does so through a pressure-rated penetrator.
- [Pressure Hull](/the-boat/pressure-hull/?format=md): The sealed cylinder that keeps one atmosphere of dry air around the electronics.
- [Syntactic Foam](/the-boat/syntactic-foam/?format=md): Buoyancy you can machine: glass microspheres in epoxy that float but don't crush.
- [Battery Pack](/the-boat/battery-pack/?format=md): The energy store. Lithium cells in a pressure-tolerant arrangement with its own BMS.
- [DC-DC Converters](/the-boat/dc-dc-converters/?format=md): Step the raw battery voltage to the clean rails each node actually wants.
- [Generator Control Node (GCN)](/the-boat/generator-control-node/?format=md): The brain of the power system: it decides charge, discharge, and load-shed policy.
- [Keel Cooling Loop](/the-boat/keel-cooling-loop/?format=md): Waste heat dumped straight to the sea through the hull — no fans, no air.
- [Power Distribution Bus (PDB)](/the-boat/power-distribution-bus/?format=md): The central DC bus that takes the battery and feeds every node through fused, switched rails.
- [Control Surfaces](/the-boat/control-surfaces/?format=md): Fins that steer the vehicle by deflecting flow as it moves.
- [Dual Motor Node (DMN-01)](/the-boat/dual-motor-node/?format=md): Two coaxial, contra-rotating motors that turn battery amps into thrust.
- [Rim-Driven Thruster](/the-boat/rim-driven-thruster/?format=md): A motor with no central shaft — the magnets ride the blade tips inside the duct.
- [Shroud & Stator](/the-boat/shroud-stator/?format=md): The duct around the prop that boosts thrust and straightens the wake.
- [Thrust Vectoring](/the-boat/thrust-vectoring/?format=md): Steering by aiming the thrust itself — the way to manoeuvre at zero speed.
- [Behaviour Tree Executive](/the-boat/behaviour-tree-executive/?format=md): The decision layer that runs the plan and reacts when reality disagrees with it.
- [Fault Management](/the-boat/fault-management/?format=md): Detects faults, contains them, and gets the vehicle home safely.
- [Mission Planner](/the-boat/mission-planner/?format=md): Turns a high-level goal into the ordered waypoints and actions the vehicle executes.
- [ROS 2 Autonomy Stack](/the-boat/ros2-autonomy-stack/?format=md): The software nervous system: every sensor, actuator, and decision as cooperating nodes.
- [State Estimator (EKF)](/the-boat/state-estimator/?format=md): Fuses every noisy sensor into one best guess of where the vehicle is and how it's moving.
- [ARGUS-6 Imaging Sonar](/the-boat/argus-6-imaging-sonar/?format=md): The 360° active sonar that lets the vehicle see the seafloor and obstacles in the dark.
- [Doppler Velocity Log (DVL)](/the-boat/doppler-velocity-log/?format=md): Measures speed over the seabed by the Doppler shift of its own reflected pings.
- [Forward-Look Obstacle Avoidance](/the-boat/forward-look-avoidance/?format=md): A dedicated look-ahead so the vehicle stops before it hits what it didn't expect.
- [MIMO-FAS 3D Sonar](/the-boat/mimo-fas-sonar/?format=md): Multiple transmitters and a fast array that build a true 3D picture, not just a slice.
- [Passive Acoustic Intercept](/the-boat/passive-acoustic-intercept/?format=md): Listening only — detecting other sources without ever revealing your own position.

## Guides

- [ARGUS-6: Building an Imaging Sonar — Why sonar, not cameras](/guides/argus-6/why-sonar/?format=md)
- [ARGUS-6: Building an Imaging Sonar — The transducer array](/guides/argus-6/the-array/?format=md)
- [ARGUS-6: Building an Imaging Sonar — Transmit & receive front end](/guides/argus-6/transmit-receive/?format=md)
- [ARGUS-6: Building an Imaging Sonar — Beamforming the image](/guides/argus-6/beamforming/?format=md)

## Roadmap modules

- [Pressure Hull & Layout](/modules/M-01/): Done
- [Keel Cooling](/modules/M-03/): Done
- [Power Distribution (PDB)](/modules/M-05/): In progress
- [Generator Control Node](/modules/M-05a/): Planned
- [Stability & Buoyancy (SBN)](/modules/M-04/): In progress
- [Dual Motor Node (DMN-01)](/modules/M-06/): In progress
- [ARGUS-6 Imaging Sonar](/modules/M-07/): In progress
- [Hybrid Comm Node](/modules/M-09/): Planned
- [ABYSS-Link Acoustic Modem](/modules/M-23/): Planned
- [ROS 2 Autonomy Stack](/modules/M-14/): Planned