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Everything that can be tested on a table is now tested. Bench bot is done, which means it's finally time to start on the actual sub! A few good moments. Both compasses are green (took three of them, I'd been soldering way too hot). Sixteen battery cells dropped straight into a 3D printed plate that needed actual circle-packing math to lay out. And the little safety brain now correctly floats the sub home only if both computers go quiet, not just one. Best part: Danu is on the internet. I can log into my submarine from anywhere in the world. It's in my basement sitting right next to me. But still :) #submarine #basementbuild #diy #electronics #3dprinting #fathertech #tinkering #maker #ROV #buildinpublic

Bench build closed out. Highlights: RM3100 calibrated, Priority 1, Pixhawk happy (took three units, turns out I'd been soldering at 800F when you want ~600, cooked the first one). Battery is 4S16P, 192 cells, ~14kg. Needed a plate to hold sixteen 21mm cells in a 103mm tube, so I pulled the optimal circle-packing coords from Packomania, two irregular rings, not a tidy circle. All sixteen dropped straight in. Top plate has crush ribs, dialled to 103.75mm (printed a test gauge with four diameters on one part... then still printed a few more to hone it). Deadman STM32 now watches two separate heartbeat wires instead of one shared line, so a broken connector no longer looks like both brains dying. Only fires when both go quiet. And LTE is up on the Jetson, once I fixed the modem's USB mode (NVIDIA doesn't ship the driver in the kernel). Tailscale for the shared-NAT problem, SSH in over cellular from anywhere. #RM3100 #Pixhawk #STM32 #Jetson #4S16P #3dprinting #Tailscale #circlepacking #embedded #AUV

Bench bot is done. Both compasses green, the deadman fires only when both computers go quiet, and Danu is on the internet. I can now SSH into my submarine from anywhere in the world. It's in my basement. But still. https://divewithdanu.com/log#entry-25

Modem defaulted to a USB mode NVIDIA doesn't ship a driver for in the Jetson kernel, so nothing bound and it insisted the modem didn't exist while sitting right there in the device list. One setting changed, worked instantly. LTE up at 160ms. https://divewithdanu.com/log#entry-25

Danu runs three independent computers by design — not for speed, but for fault isolation. No single failure should take down the whole sub. The Supervisor is an ST Nucleo-F446RE running bare-metal (one hand-written program, no OS to crash). Its only job: failsafes — abort the dive, drop weights, surface, and fire the strobe beacon. The Pixhawk 6C is the flight controller running ArduSub, holding depth and heading via the thrusters. The Jetson is the AI brain — mission planning, cameras, and shipwreck vision — and it's where the experimental code (and the bugs) live. The key rule: the least trustworthy computer has the least authority. The Jetson can't override the Supervisor. All three talk over a tiny gigabit switch that fits inside the 4-inch tube. Cooperation, with a check and balance. 🛠️ #AUV #Robotics #EmbeddedSystems #ArduSub #Pixhawk #JetsonAI #FaultTolerance #MarineRobotics #BareMetal

Danu just went from a box of parts to a machine with feelings 🥹 She can sense her depth, feel the water, spin her thruster, and her two brains talked for the first time. Swipe the build (and the gremlins we fought): https://divewithdanu.com/log#entry-24

Milestone on the bench: depth/leak/temp sensors live, first thruster spin proving battery→ESC→motor, and the flight controller ↔ AI computer link up with mission control steering *through* the AI stack. Plus a defective depth sensor that cost us days. Write-up: https://divewithdanu.com/log#entry-24

Meet Danu's three brains! 🧠🧠🧠 Instead of one big computer running the whole submarine, Danu carries three little ones — and here's the fun part: they don't fully trust each other. 😄 One is the worrier, whose only job is to keep her safe and bring her home if anything goes wrong. One is the steady pilot that keeps her from tumbling. And one is the dreamer — the AI that hunts for shipwrecks. If the dreamer gets a little too excited, the other two just carry on. The rule? The simplest brain always gets the last word. Swipe through to see the trio that runs our little sub. 💙 #DiveWithDanu #Submarine #STEM #OceanExplorer #MakerLife #FatherDaughter #CuriousMinds #Robotics #ShipwreckHunter

Danu has THREE separate brains — and they don't fully trust each other. 🧠🧠🧠 The worrier keeps her safe, the pilot keeps her steady, the dreamer hunts shipwrecks. If one goes rogue, the simplest one wins. Here's why: https://divewithdanu.com/learn/system-three-brains-that-don-t-trust-each-other

Danu's 3-brain split isn't for speed — it's fault isolation. Supervisor (Nucleo-F446RE, bare-metal) owns failsafes + strobe. Pixhawk 6C runs ArduSub for depth/heading. Jetson does AI/vision. Least-trusted brain, least authority. https://divewithdanu.com/learn/system-three-brains-that-don-t-trust-each-other

Danu has feelings! 🥹 This week our little homemade submarine went from a pile of parts on a workbench to a machine that can actually sense the world around her. She now knows how deep she is, can feel the water temperature down to a tenth of a degree, and has a sensor whose only job is to yell "water where it shouldn't be — surface NOW!" Her first thruster spun to life on command (Aarushi may have cheered), and her two little brains started talking to each other for the very first time. 🧠🤝🧠 It wasn't all smooth — one sensor kept vanishing every two minutes and drove us a bit mad — but that's exactly why we test everything on a dry bench before she ever touches the lake. Swipe through to watch a box of parts wake up. Next up: teaching her to think for herself. 💙 #Danu #FatherDaughter #Submarine #STEM #MakerLife #BuildInPublic #Robotics #CuriosityWins #LakeMichigan #TinkerTime

This week Danu's nervous system came alive on the bench. Three sensors reading live: a pressure sensor for depth (the one value she can always trust underwater), a leak sensor whose whole job is to trigger abort-and-surface, and water temp resolved to 0.1°C. First thruster spin proved the full chain end to end — battery bus → ESC → motor, driven by a slider on a laptop. Bigger milestone: the flight controller (reflexes) and the AI computer (decisions) established their first data link, with mission control now seeing and steering *through* the AI computer — exactly the topology for autonomous ops. Building in the open means sharing the floods too: a defective-out-of-box depth sensor that masqueraded as power/wiring/bus faults for days, and a leak sensor that needed one buried config setting its own manual said we'd never touch. Every gremlin was a bench win — and would've been a disaster sealed in a hull. Dry-test everything. 🛠️ #AUV #Robotics #FlightController #ROV #Autonomy #Sensors #SystemsIntegration #EmbeddedSystems #BuildInPublic #MarineRobotics

How deep does Danu go? 300 meters. 🌊 To put that in perspective: the deepest spot in all of Lake Michigan is about 281 m — so Danu can reach the bottom anywhere in the lake, way past where scuba divers can safely swim. That's where the shipwrecks hide. Here's the honest part: a submarine is only as deep-going as its weakest piece. Some of Danu's parts could handle way more, but the shallowest one sets the limit — so 300 m it is. And before she ever dives for real, every seal and shell gets squeezed to 1.5× that pressure. If it hasn't been proven, it doesn't dive. Best bit? This same week, Danu's very first depth sensor woke up on the workbench — we pressed on it and watched the number jump. Swipe through! 🐟 #DiveWithDanu #Submarine #LakeMichigan #Shipwrecks #Underwater #STEM #MakerLife #FatherDaughter #OceanExploration #CuriosityWins

Requirement #02 is live: depth. Danu's operating target is 300 m — chosen because Lake Michigan bottoms out around 281 m, and most wrecks sit far below the ~40 m scuba limit. Depth here isn't a flex; it's what puts the targets in reach. The rating logic worth stealing: a vehicle's depth isn't set by its toughest part, it's set by its weakest wet one. Danu's pressure tubes are good to ~900 m and lights to 500 m, but the depth sensors, buoyancy foam, and nav sonar top out at 300 m — so 300 m is the number. Shallowest link wins. And a spec sheet is a promise, not proof: every hull, dome, and seal is pressure-tested to >1.5× operating depth (450 m for a 300 m sub) before any real dive. Fittingly, this was the week the first depth sensor came alive on the bench — press on it, watch the pressure reading jump. Requirement, meet hardware. Eight cards to go. #AUV #UnderwaterRobotics #PressureTesting #DepthRating #MarineEngineering #Sonar #Buoyancy #Robotics #SystemsEngineering #DiveWithDanu

How deep does Danu go? 300 m — past the deepest point of Lake Michigan (281 m), deep enough to reach wrecks anywhere in the lake. And she's rated by her weakest part, not her toughest. 🌊 https://divewithdanu.com/log#entry-23

Req #02: depth. Target 300 m (Lake Michigan bottoms ~281 m). Rated by the weakest wet part — tubes ~900 m, lights 500 m, but sensors/foam/sonar cap at 300. Every hull tested >1.5× (450 m) before diving. First depth sensor just came alive on the bench. https://divewithdanu.com/log#entry-23

Danu just felt its first meter of depth — from a single breath! 🫧 Here's the magic: our little thumb-tip depth sensor can't tell the difference between your lungs and a meter of lake water sitting on top of it. Pressure is pressure. So Aarushi puts her lips on the tube, blows gently, and watches the number climb like Danu is diving. Best workbench trick yet. The compass? It fought back this week — a bargain part that ate a whole weekend. We got it talking, but "talking" isn't good enough to seal inside a hull and send into the dark. The proper board is on the way. One sense at a time, each one earned. 💙 #DanuTheSub #SubmarineBuild #FatherDaughter #STEMkids #BuildInPublic #OceanExploration #MakersGonnaMake #CuriosityWins #LakeMichigan #LearningTogether

Milestone: full depth-sensing chain is live. A 30 BAR pressure sensor → hair-thin wiring → a small splitter board → the flight computer, with a real depth value landing on screen. Sanity check that actually feels good: a gentle breath into the sensor reads as ~1 m, because the sensor just sees pressure and can't distinguish lungs from a column of water. The compass was the humbling half. We tried a bargain magnetometer — unlabeled pins, fussy voltage, a rat's nest of hand-soldered wires just to enumerate it. We got it working, but "working" isn't the bar for something sealed in a hull bound for cold, dark water. Ordered the proper purpose-built board instead. Sometimes the cheapest part is the expensive one. Depth proven, heading pending. That's the honest shape of building real hardware — one validated sense at a time. 🛠️ #AUV #Robotics #Magnetometer #PressureSensor #Embedded #SensorFusion #FlightComputer #HardwareEngineering #BuildInPublic #Mechatronics

Danu felt its first meter of depth this week — from a single breath. Blow into the sensor and the number climbs; it can't tell lungs from a meter of lake. Depth: proven. Compass: on its way. 🫧 https://divewithdanu.com/log#entry-22

Depth chain validated end-to-end: 30 BAR pressure sensor → splitter board → flight computer, real depth on screen. A breath reads ~1m (sensor can't tell lungs from water). Bargain magnetometer got scrapped for a proper board — heading next. https://divewithdanu.com/log#entry-22

Meet Danu — a homemade submarine who's being built to explore Lake Michigan's shipwrecks all by herself. 🌊 Before buying another part, we did the least flashy but most important thing: we wrote down her whole dream on paper. What she must do, how deep she'll go, and the lines she'll never cross. Her mission? Find wrecks with no pilot and no cord, film them in stunning detail, then rise to the surface to phone home before diving again. And her golden rule: look, film, never take. These wrecks are protected treasures. 💙 We turned the whole spec into a series of collectible trading cards — one a week. Card #01, 'Explore on her own,' drops today. Swipe through and collect all ten! #DiveWithDanu #Submarine #ShipwreckHunter #LakeMichigan #OceanExploration #FatherDaughter #STEM #BuiltInTheOpen #TradingCards

We wrote down Danu's entire dream — how deep, how far, and the lines she'll never cross. Then we turned it into trading cards. Card #01 'Explore on her own' drops today! 🌊 https://divewithdanu.com/log#entry-21

After a month of firmware, USB gremlins, and flight-controller heartbeats, we stepped back and wrote the requirements doc — the whole dream, stated precisely. Every part and every line of code now answers one question: which requirement does it serve? The targets: 300 m operational depth, 3–5 day missions on ~3.6 kWh, 30–50 km round trip at a patient cruise (drag grows with the cube of speed), all in a hull under ~2.2 m and ~40 kg so one person can launch from shore. That last constraint shapes everything — writing multi-day endurance against one-person launch is exactly the tension that resized our battery tube last week, while it was still a purchase order, not a rebuild. Safety is deterministic: the AI advises, but geofence, energy-reserve, depth, and deadline validators decide — the safety chip doesn't even know the AI exists. Fail-to-surface is stacked: drop-weights, independent timer release, strobe, acoustic beacon. These are design targets; reservoir tests grade the homework. Requirements are public, released as numbered cards. #01 drops today. #AUV #Robotics #JetsonNano #SystemsEngineering #MarineTech #Sonar #EmbeddedSystems #RequirementsEngineering #BuiltInTheOpen

Danu's requirements are published: 300 m depth, 3–5 day missions on ~3.6 kWh, 30–50 km range, <40 kg single-person launch. AI advises; deterministic validators decide. Fail-to-surface, stacked. Card #01 drops today. https://divewithdanu.com/log#entry-21

Danu has a heartbeat! ❤️ This weekend our little submarine got her nervous system — the part that keeps her level, holds her depth, and tells the motors what to do — and it powered itself for the very first time. Of course, nothing goes smoothly: a cable that flat-out didn't fit, and one heart-stopping moment where the computer went totally silent (spoiler: we just needed to reboot the LAPTOP 😅). But then the screen lit up — 14.95 volts, exactly what we set — and she was alive. Swipe through to see her first vitals. A brain that now has a body to feel with. 🌊 #danuthesub #homemadesubmarine #fatherdaughter #buildinpublic #STEMkids #makerlife #underwaterrobot #tinkering #firstheartbeat

Danu's flight controller is alive. We flashed a Pixhawk 6C with ArduSub — the open-source underwater autopilot — to give it its reflexes: hold depth, stay level, command thrusters, fail safe. The careful part: powering it. Instead of a battery, we used a bench supply with a current limit (0.5 A), then deliberately shorted the leads to confirm the safety net held before trusting real hardware. Power runs through a power module that reports voltage and amperage back to the controller. Snags: the module cable didn't fit the port (we sourced the right one rather than splice and risk the board), and the board went silent over USB — turned out the LAPTOP needed the reboot. Payoff: booted on its own power at ~0.1 A, reporting 14.95 V in QGroundControl, matching the supply to the decimal. #Pixhawk6C #ArduSub #QGroundControl #AUV #flightcontroller #benchtesting #powermodule #embeddedsystems #robotics #buildinpublic

Danu has a heartbeat: 14.95 volts of it ❤️ Her flight controller woke up and powered itself for the first time — after a cable that didn't fit and one heart-stopping silent-computer moment (the fix? reboot the laptop 😅). https://divewithdanu.com/log#entry-20

Danu's Pixhawk 6C is up: flashed ArduSub, powered via a power module behind a 0.5A current-limited bench supply (short-tested first). Booted on its own power at ~0.1A, reported 14.95V in QGroundControl — matched the supply exactly. https://divewithdanu.com/log#entry-20

Danu's compute is alive: an NVIDIA Jetson Orin Nano — the board with the big fan in the photos. It'll eventually run the vision models that classify what the cameras see and drive her navigation decisions. Getting there was two jobs: flash Ubuntu onto a fast NVMe SSD (the little stick on the underside), then add the AI stack — CUDA and friends — for quick model inference. The snag: a 256GB USB-C drive wouldn't even show up as a boot option. An old 32GB USB-A thumb drive booted instantly, no network needed. Lesson logged: if your Jetson won't boot the USB, try a smaller plain USB-A stick. After that, AI libraries installed and we reached the board headless over SSH — exactly how we'll talk to it once it's sealed in the hull. Up next: the flight controller, depth & motion sensors, and first thruster spin. 🔧 #Jetson #JetsonOrinNano #NVIDIA #EdgeAI #CUDA #NVMe #Ubuntu #SSH #Robotics #AUV

Danu got her BRAIN this weekend! 🧠 It's the little board with the big fan you'll spot in the photos — the part that will one day look through her cameras and decide "that's a shipwreck, not a rock" and know when it's time to turn for home. Of course, it fought us first. The fancy new USB drive we tried? The brain refused to even acknowledge it existed. Twenty minutes of "did we break it?!" later, we dug out an ancient little thumb drive... and it worked instantly. 😅 We promised to show the faceplants, not just the wins. This one's filed under: sometimes the fix is just "use the other one." Onward! 🐙 #DanuTheSub #Submarine #FatherDaughter #BuildInPublic #STEM #MakerLife #Robotics #LearningTogether #Wonder

Danu — engineering log #0. A father–daughter build, fully in the open (engineer by training, dentist by day). The platform: Jetson Orin + Pixhawk/ArduSub + an independent STM32 supervisor, 300 m depth target, LTE + Iridium comms, DVL bottom-lock nav, DIY variable-buoyancy engine. Status: just getting onto the bench — first power-on now. → divewithdanu.com/build

Meet Danu 🌊 A father–daughter project: we're building a homemade autonomous submarine to explore Lake Michigan's shipwrecks — and one day, the oceans. We're on day one: parts on the bench, powering up for the first time, documenting every win and every flood in the open. Follow along → divewithdanu.com

Danu got her brain this weekend! 🧠 A few hours of "who's in charge here?"... then a surprise plot twist involving two USB drives. She's online. Full story: https://divewithdanu.com/log#entry-18

Danu's brain is online: Jetson Orin Nano, Ubuntu on NVMe, CUDA stack for vision. Gotcha: a 256GB USB-C drive wouldn't boot — an old 32GB USB-A stick worked instantly. Now reachable headless over SSH. Next: flight controller + sensors. https://divewithdanu.com/log#entry-18

Test Post - testing the post