rHXN

Building a custom octocopter from scratch with no prior hardware experience

https://karolina.mgdubiel.com/drone/
By: noleary
HN Link
kar0lina - 13 hours ago
Hi!! I'm Karolina, and this is my project! Had no idea this got posted until someone DMed me about it on LinkedIn. Feel free to ask any questions or follow along via X (karolina_dubiel)

Thanks so much for all the kind words, it means a lot!

jdthedisciple - 5 hours ago
You seem very talented, great work!
hazrmard - 17 hours ago
This is very impressive! I researched fault-tolerant octorotor control using RL in grad school for a NASA project. Perhaps this may be helpful[1, see section 8.3]! The field is moving fast, so there may be better or more suitable approaches out there now.

For folks who are interested in UAV physics, I wrote up an explainer[2].

[1]: https://drive.google.com/file/d/1RTEVRd0XCWLuDXY2nkbmYuOaa5x...

[2]: https://iahmed.me/post/drone-physics/

quibono - 13 hours ago
This is lovely, thanks!
urban_winter - 4 hours ago
I find it very hard to believe that someone who has never done any CAD could design that with Fusion 360 in a day. I do lots of 3D design with Fusion and there is a serious learning curve. It's not something you can pick up in a day. She is doubtless much smarter than me, but that's not credible.
_jss - 24 minutes ago
Did you look at the parts and content, or just leap to this assumption?

My first couple days with Fusion had similar outcomes, and this is totally credible. There are extremely talented YouTubers that have information-dense guides through many features. It's totally plausible with that and having a mentor showing you a tool to succeed here.

Why add negativity to something cool? There is a build log! It's well done and tangible! It's not slop! Celebrating is always more fun than humbugging.

Tossrock - 17 hours ago
Something I've wondered for octocopters - could using a ring instead of arms be beneficial for weight? 6.28r < 8r, but then again the arm radius is usually less than the full circle, and some components want to be centrally located, etc. I could imagine holding the central components in tension via light filaments (carbon fiber, nylon, etc) in tension, vs having to have rigid structure, but the small factor between 6.28 and 8 and maybe makes it not worth it.
rolph - 17 hours ago
consider "tiled" hexagons, like honycomb.

large schedule 40 or 80 tubing sliced into rings would be pretty quick source material, starting with duct tape and zipties until you find a good arrangment then get into the glue and screws.

robocat - 5 hours ago
I'm not sure what the modern equivalent of LMGTFY is. But I asked AI "For 8 rotor drones, what are the main reasons for using arms rather than a ring (or maybe a ring with a tensioning wire)"

asking AI "

lhaussknecht - 3 hours ago
Cool project! For a DIY beginner, what would be a good starting point for a "normal" drone/octocopter project?
geod_of_ix - 19 hours ago
I love everything about this. Well done! but missed opportunity to name it R_of_L-copter.
pjdkoch - 22 hours ago
Kudos for such a great learning journey!
felooboolooomba - 19 hours ago
This is cool as sugar! I have to ask though, how many end mills did you go through milling G10 fiberglass and carbon fiber‽

I've heard the dust from carbon fiber is second to asbestos for inhaling.

faeyanpiraat - 4 hours ago
Also there was a video about touching the edges of carbon fiber where it is not surface treated is embedding countless small shards of carbon into your skin, only visible through magnification, which cannot be healthy..
melagonster - 22 hours ago
I do not notice that the time of posts is reversed haha. I am confused whether you had build it.

Thank you, it's cool!

kar0lina - 8 hours ago
Newest is at the top :D If you press the little "Collapse All" button on the top right of the blog posts, you can see the full timeline + dates of the entries.

I did start by designing/building a regular FC (no RL or anything) and am doing RL training afterwards, so I agree that the whole timeline looks a little confusing without background context since it goes real drone --> sim haha

quibono - 1 day ago
If I were to get a dirt cheap Chinese drone, would that be more likely to use RL or MCP? What’s the “standard”?
bri3d - 21 hours ago
Low end and most open source stuff will use a PID inner loop for “fast path” control (stabilization) and either a second PID loop or something a little better (Kalman filter etc) for the slow path (position / path hold).

Higher end stuff will use a ton of inputs (visual odometry, binocular vision, lidar, range finding, etc) fused into some kind of proprietary blended algorithm that you could probably call an MPC.

RL is pretty cutting edge, especially for fast path motor control; there are a lot of university competitions for drone control that lead to a lot of papers and projects in the space (some promising) but most commercial stuff has not adopted this yet, certainly not at the low end.

spaqin - 23 hours ago
PID is more than enough to keep level. FPV relies on manual flight, but you can get Ardupilot for autonomous missions. There's no need for RL, nothing to gain here; level flight and following waypoints is a solved issue already.

And frankly as a pilot, I'd rather not see any completely autonomous drones with no oversight in the sky - that's one incident away in which blame cannot be put solely on the operator from getting the hobby completely banned.

dragoman1993 - 18 hours ago
As a researcher in the autonomous robotics space, there is a lot to gain in RL over PIDs and manual flight.

The delta between what is possible with current autonomous flight missions and manual FPV style flight is by having a brain on board that can dynamically adapt to a changing environment. There are a finite amount of PID profiles for each steadystate solution that a researcher can preprepare for. But RL allows an overarching heuristic to transiently alter the PIDs depending on the changing environment.

We use PIDs because analyzing robotics platforms as seeking a steadystate dramatically simplifies the math needed to where its computationally possible for us to solve for a situation.

We use RL in systems that have continuously changing environments with transient solution spaces that are easier to model in hyperspace with a RL model.

Take for example platforms that have tiltrotors. They ideally have a minimum of 3 PID profiles for flying. One when it best fits a multirotor profile. A second when it is transitioning from multirotor to fixed wing flight, and a third for when fixed wing flight is established. What happens when the researcher has a need to fly in the transition state, or subconfigurations of the states? How many PID profiles are you looking to think of and train for? This is where RL has dividends.

quibono - 23 hours ago
Interesting - thanks! OP's drone IS using RL and that's what jumped out at me - it felt a bit overkill for the usecase.
kar0lina - 12 hours ago
Hey! This is a great question because RL is overkill for my use case, you're right! The reason I'm using RL is because I wanted an RL project on real hardware, so I built this idea of a drone project around that concept, not vice versa. A lot of people on X have brought up alternative solutions -- like MPC -- that might be a better approach to this problem engineering-wise. I just really wanted a real-world RL problem and this was kind of the first cool idea I thought of :D

I'm sorry for the late response, I didn't realize someone had posted my project

the__alchemist - 20 hours ago
Phrased in a slightly different way, assuming the standard is Betaflight/Ardupilot/PX4. (This article uses BF): Inner PID rate loop; this compares IMU-measured rates vs that commanded by manual controls. This might run at 1-4kHz.

On top of this (Maybe at a few hundred hz), you can add outer controls to set attitude. This could be an autopilot, or having the controls command attitude instead of rate. Betaflight pilots usually don't both with this, and have the simple setup of control maps to rate.

I've programmed firmware using a weird hybrid where the controls command a change in the target attitude. So it flies like rate, but has the forced attitude stability of an attitude-based control system. Non-standard, but makes it so you don't need to worry as much about tuning the PID loop. In practice, you can do full aerobatic flight with this like you'd do with a rate-only setup. (Basically, there is a commanded attitude quaternion; controls nudge it; the PIDs update motor power to maintain this commanded quaternion.)

cyclopeanutopia - 1 day ago
Will follow a fellow Polish inventor! :)
kar0lina - 13 hours ago
Hi!! Would love to connect :) My X is karolina_dubiel and LinkedIn: https://linkedin.com/in/karolinadubiel
TacticalCoder - 21 hours ago
Amazing: I'm watching lots of homemade builds atm.

I've got a question: why CNC milling and not just FDM 3D printed parts? TFA doesn't talk much about it except saying she went to a machine shop.

> 2. CNC milling forms out of G-10 fiberglass (arms) and 5mm carbon fiber (body)

TFA also says this:

> The solution for this is to 3D print a 0-tolerance assembly jig to hold the arms in perfect position while the center of the drone is superglued together.

Why not 3D print it all?

There's this guy who built a drone that can fly for 3 hours and cover hundreds of miles, 3D printed at home on a $250 printer:

https://youtu.be/e7AIKGDrlgs

Then there was the $200 K quote for the body for a car that just did Pike's Peak with a four times Pike's Peak champion and instead the team... 3D-printed the car's body at home (something like 40 parts, assembled together), which cost them less than $2 K to make (1/100th of the quoted price for the car's body). Here's the vid where they print all the parts (on a $1500 consumer printer):

https://youtu.be/nt85nTMnY1w

Basically: why CNC milling and not 3D printing at home when many drones enthusiasts (and now too people building race cars) simply print parts at home on a consumer-grade 3D printer?

bri3d - 18 hours ago
For "copter" style drones, 3D printing is basically a "noob" meme at this point; everyone thinks it's a good idea, tries it, and realizes that it's actually really hard and doesn't work.

Copter-style drones are exposed to vibration across a huge frequency range in every axis, and it's almost impossible to avoid really nasty resonance issues using generally-printable FDM filaments and "standard" design techniques; it's a lot easier to just use super-stiff carbon fiber and CNC it.

For planes, like what you linked, 3D printing is more "plausible" than for copters but also not really practical; you can 3D print a good plane, but plastic lacks the durability and favorable weight characteristics of foam - plastic planes tend to be "one time crashed" while foam is easy to repair, restore, and rebuild.

the__alchemist - 20 hours ago
Stiffness. Important for how the frame behaves under load and buffetting etc.
kar0lina - 13 hours ago
^^ This was why I opted not to 3D print the whole thing :)
orn - 18 hours ago
Super cooool
tamimio - 19 hours ago
Love it, great to explore and learn, and I like the mixed background too of cybersec and robotics (all the way to CNC), just like myself, I think these two new fields will make a new industry, similar to OT cyber but more niche.

Which also means great people can go beyond what’s their school was about, so a CS major doing CNC isn’t “weird” or different, I remember when applying for jobs in systems in aerospace industry and get rejected despite having a systems background too, with feedback of “they are looking for people with education only in aerospace”, which is idiotic thing to consider.

So good luck OP, start exploring hacking mavlink or similar protocols which is what im working on.

mickeyp - 22 hours ago
You know you're doing a great job, OP, when the peanut gallery here has nothing more substantial to add than to critique your em-dashes; greek-latin root word mix-ups despite the common vernacular having moved on from that; and lack of title brevity.

Congratulations --- this is a super cool project. I wonder if you've considered using ultralight filaments and 3dprinting the frame? PLA is stiff but brittle, and I know Bambu and a few others sell specialised versions that supposedly weigh less than normal.

dang - 14 hours ago
> the peanut gallery here has nothing more substantial to add than to critique

The comments in this thread are overwhelmingly positive by now. Watch out for the contrarian dynamic! (https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...).

Needlessly negative comments tend to show up first in a thread, while positive responses emerge over time. (Why? well, I have my theories: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&sor...)

It's a fine thing to counteract that with a positive comment, but if you can, please omit the snarky bits (such as in your first paragraph). I know they're tempting, but they tarnish the positivity and substance that you correctly want to see in the discussion - and in the end they "bond" (in the molecular sense) more with the negative posts than with the outright positive ones.

Your second paragraph on its own would make a much better (indeed excellent) post - and that is the best way to combat the negativity.

(I know my reply here is itself an instance of the thing I'm talking about - responding negatively to the negative bits. Sorry!)

bri3d - 21 hours ago
Most filament based printed frames end up with really nasty resonance; it’s possible to engineer damping around the issue with some clever 3D design if the parameters of the prints are measured, but overall 3D printing copter frames doesn’t tend to be a straightforward solution.
kar0lina - 13 hours ago
Hi! Thanks for your kind words. I actually had no idea this got posted here, I'm Karolina, and this is my project! Really cool to see some feedback here! I went with CNC cutting over 3D printing just because I wanted to avoid any stiffness/vibrational issues. I don't actually have any prior drone experience, so I wanted to play it really safe with that.
felooboolooomba - 19 hours ago
I wish we had some standard filament testing that most manufacturers were willing to provide results for.

Until that happens, this guy here is probably the next best thing: https://www.youtube.com/@MyTechFun

Plot twist: many of the "special" filaments aren't special at all or at least very exaggerated.

cwmoore - 22 hours ago
Yes. And when your design is simply beautiful as this is:

https://karolina.mgdubiel.com/drone/drone-img/05-30-26/cnc_c...

the__alchemist - 21 hours ago
I agree with your first point.

The milled fiberglass the author used is a much better UAS frame material than anything from a filament 3d printer due to stiffness and related considerations.

mickeyp - 21 hours ago
Oh no doubt. I'm no drone expert!
spiralcoaster - 16 hours ago
It's good thing you threw in that suggestion then!

<reads blog post of engineer building a small scale internal combustion engine>

I wonder if you've considered making the piston rods out of legos?

mickeyp - 2 hours ago
But people do 3d print frames for drones and gliders. It's undoubtedly worse than carbon fibre, I guess, but I found it interesting enough to share that you can buy especially lightweight filaments designed for aeronautic stuff.
the__alchemist - 13 hours ago
I will stick up for spiralcoaster. This post is direct and could be interpreted as offensive. Sarcasm both in general, and especially over text is often not appreciated. (It partially depends on culture). Yet, I think this analogy is appropriate here, and I was thinking along the same lines.
sanex - 22 hours ago
People are so jealous. This is cool as hell.
felooboolooomba - 19 hours ago
Something happened recently that attracted a whole bunch of quite ignorant and frustrated people to this site.
Joel_Mckay - 14 hours ago
Don't forget bot AstroTurf, and several con artists attempting various scams. =3
lysace - 18 hours ago
So many activists of different kinds.
Joel_Mckay - 14 hours ago
Activists have political ambitions, but most LLM nonsense is just engagement farming. =3
kobalsky - 20 hours ago
It's cool, but I could have done it 2.45 weeks!
Mona1 - 21 hours ago
[dead]
ramon156 - 23 hours ago
Hm making an AI assisted page and replacing the emdashes with double dashes seems like more work than to just rewrite the text yourself. Not sure why you would do that.
kar0lina - 13 hours ago
I use Claude Code to help me with the updates on my website/blog because I have a full time job and try to squeeze this side project into as little time as possible :) It's definitely not fully AI-generated, though, I love writing, and I'd consider myself "savvy" enough haha. But it's ok if you don't agree! Sometimes it's easier to use Claude to condense ideas (for ex, the abstract) when I'm on a time crunch. But either way, Claude definitely didn't solder, CAD, or CNC-cut anything for me :D

I don't think there's any shame in using LLMs to save time on documenting your projects. Let's be kind and positive to each other!!

iterateoften - 22 hours ago
Tbh this is cooler than anything on your github so he (edit: she) can do what he wants IMO
quibono - 23 hours ago
The abstract certainly smells like 100% LLM-generated text.
dylan604 - 23 hours ago
What? That’s a simple find and replace vs rewriting the whole thing. If someone had the savvy to write the thing, they probably wouldn't have been using the the assistant in the first place. Either way, comparing a find/replace to rewriting is farcical
mathisfun123 - 21 hours ago
> more work than to just rewrite the text yourself

You think s/—/--/g is more work than rewriting a whole article? Is this what you're saying?

bilsbie - 15 hours ago
You could be more fault redundant by having two motors and props on each axis.
m3kw9 - 23 hours ago
Why not just say from scratch instead of no prior experience, is it to brag
myrmidon - 22 hours ago
Might be intended to preemptively deflect criticism of "reinventing the wheel"/solving subproblems in a non-standard/convoluted way.

I'd expect an engineering project with "no prior experience" to take weird/experimental approaches more often compared to a "from scratch" project (where I would expect proven minimalism instead).

chupchap - 4 hours ago
This person made it from scratch with no prior experience, so the bragging rights are well earned.
felooboolooomba - 19 hours ago
"from scratch" and "no prior experience" have very little in common.
adrian_b - 1 day ago
Nit pick:

The name "octocopter" does not make sense. "Helicopter" is a compound word made of "helico-" and "pter", which means "screw-wings". "Octo-" means eight, "-co-" means nothing.

"Octopter" would be a correct compound word meaning "8-wings", but that would be ambiguous, so the object discussed in TFA is better named just "8-propeller drone".

Mtinie - 1 day ago
That ship has long sailed. You’re correct, but the author isn’t the one who “named the thing” in this case, they are just using the name commonly used to describe it.

Multi-rotor drones have been called tricopters, quadcopters, hexacopters, octocopters based on their propeller counts conversationally for as long as I can remember.

There are plenty of commercial vendors who use the exact term for their expensive industrial drones.

Update: I see that in the four minutes it took for me to validate my initial inclination and post that plenty of others also had the same thought :) No need to me to belabor the point!

cryptopian - 1 day ago
This is quite a common linguistic phonomenon, where a word is rebracketed to form a new suffix, even if it doesn't make sense with the original etymology. See also -holic (alcoholic -> workaholic), -thon (marathon -> danceathon) or -gate (Watergate -> partygate). Termed a "libfix" from liberated affix
maciuz - 1 day ago
The -copter suffix is very common in the drone community.eg quadcopter is widely accepted https://en.wikipedia.org/wiki/Quadcopter
Munksgaard - 1 day ago
Similarly, "heli" is a commonly recognized clipping of helicopter: https://en.wiktionary.org/wiki/heli#English

See e.g. https://en.wikipedia.org/wiki/Helipad

ButlerianJihad - 1 day ago
Are you trying to say that it’s been co-opted? Did anyone consult the Egyptian Christian community about this?
cyclopeanutopia - 1 day ago
Hence a nit.
KPGv2 - 1 day ago
Nit pick: "nit pick" means to remove tiny bugs from hair, which this is not.

Oh, language changes and now "nit pick" means "to make trivial criticisms" even though neither "nit" nor "pick" etymologically has anything to do with criticisms? How very self-serving of you ;)

ShinyLeftPad - 22 hours ago
It's a metaphor:)
cyclopeanutopia - 1 day ago
Unrelated.
ChrisKnott - 22 hours ago
McDonald’s getting a strongly worded letter from the Mayor of Hamburg over their use of “cheeseburger”.
Closi - 1 day ago
Blame language evolving over time rather than OP, octocopter is a widely-used term for '8 propellor drones'.

A nit pick with your post - you use the word 'ambiguous' but really this is from the latin root 'ambiguus' so we don't need the supurflous 'o' in between the two u's.

afandian - 1 day ago
Well I was confused by it! I was expecting an article on amateur semiconductor fabrication. Granted, that was due to my misreading it as 'optocoupler'.
HPsquared - 1 day ago
"Copter" is a known word, short for helicopter.

https://dictionary.cambridge.org/dictionary/english/copter

mapt - 23 hours ago
On a related note, pronunciation variance in "Helicopter" -> "Helacopter" -> "Helocopter" leads to a confusing abbreviation - "Helee" vs "Heelo"
KPGv2 - 1 day ago
Counterpoint: -copter is a perfectly cromulent suffix. https://en.wiktionary.org/wiki/-copter

gyrocopter, helicopter, quadcopter, hexacopter, octocopter, parcelcopter, and—most famously—

roflcopter, https://en.wiktionary.org/wiki/roflcopter#/media/File:Roflco...

They all have their own dictionary entries.

Octocopter makes perfect sense. Everyone understands immediately what it means, and that's the only purpose of language: to convey ideas. It should be clear, which this is, and concise, which this is.

Fidelity to ancient Greek is not, and should not, be a goal for English.

_kb - 23 hours ago
Great examples. The English lexicon is continuously embiggened by the adoption and expansion of terms.
protocolture - 7 hours ago
9/10, missed opportunity for "cromulent terms" at the end there.
mwue - 20 hours ago
In this fundamental paper, the authors argue for multirotor instead of -copter. In academia, this term seems to have stuck.

https://ieeexplore.ieee.org/document/6289431

GordonS - 23 hours ago
I guess it's a play on the popular word "quadcopter", rather than "helicopter".