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Building a custom octocopter from scratch with no prior hardware experience

karolina.mgdubiel.com

41–50 of 98 posts

Re: Building a custom octocopter from scratch with no prior hardware experience

#41

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.

> 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?

Re: Building a custom octocopter from scratch with no prior hardware experience

#43
post #28

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…

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.

Oh no doubt. I'm no drone expert!

Re: Building a custom octocopter from scratch with no prior hardware experience

#44
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?

Re: Building a custom octocopter from scratch with no prior hardware experience

#45
post #3

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".

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

Re: Building a custom octocopter from scratch with no prior hardware experience

#47
post #9

If I were to get a dirt cheap Chinese drone, would that be more likely to use RL or MCP? What’s the “standard”?

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.)

Re: Building a custom octocopter from scratch with no prior hardware experience

#48

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…

Stiffness. Important for how the frame behaves under load and buffetting etc.

Re: Building a custom octocopter from scratch with no prior hardware experience

#49
post #28

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…

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.

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