Building a legged robot in 80 days
107-systems.org
107-systems.org
It's a very cool way to get hands on experience across a wide number of technical disciplines.
I found the write-up was good, I especially loved the focus on what went wrong and the last minute fixes (They're unavoidable at competitions like this - nothing like rebuilding critical parts at midnight, or scrambling to fix a bug in the 20 minutes you have between runs).
That said - I'd really have liked a cost breakdown of this bot. Just eye-balling some of the components here, I'm guessing we're around 10k, but it can vary a ton, and I'm about a decade out on pricing.
Some of the teams at the competitions I participated in went in with budgets in the low hundreds of thousands (University of Central Florida pretty consistently spent ~75k a year on their hardware, not counting travel or other expenses) and some went in with complete shoe-string budgets in the 5k range.
I'd love to get an idea of what budget was planned for this, what ended up being more expensive, and what ended up being less.
A not insubstantial amount (for me) and entirely financed out of my own pocket - 107-systems is a private team staffed with volunteers financed by donations.
I'd preferred to stay below 10k but at the end it was do or die ¯\_(ツ)_/¯ . Since you write of having participated at such events I suppose you understand ;)
The most expensive parts were the miniature hydraulics as well as the custom CNC milled parts, which were created using a service for the manufacturing of custom front panels (a plate is a plate). But also all the small parts start to add up: cables, connectors, batteries, power distributors, ...
Had you considered using laser cut parts from a place like SendCutSend? Conservatively guessing approximately $300 in cut parts if using 6061 aluminum.
Doesn't seem to make a lot of sense to mill these, they should really water jet or laser. Does SendCutSend have a water jet? Do they ship overseas? What would the air freight cost on that large package?
Those machined shafts would have been expensive. Nice to get them for free.
No they don't. Just the US and Canada. I checked out Xometry for a similar service in Europe yesterday.
From their homepage:
Laser Cutting, CNC Routing, Waterjet Cutting, Anodizing, CNC Bending, Countersinking, Hardware, Powder Coating, Plating, Tapping, Deburring
> Do they ship overseas?
Also literally answered on their homepage.
> What would the air freight cost on that large package?
What large package?
This sure is the truth... I am painfully familiar with realizing I've spent another grand at McMaster-Carr by the end of the month with a series of small purchases, each under 50 bucks individually.
The big ticket items tend to be expensive, but expensive once. It's all the nickel and dime purchases in between that can really hurt.
At day 0, they could likely have found an SBC with native CAN and RS-485 (or just used a UART to 485 converter), and enough USB ports for the sensors, which would have simplified the design a lot. A different battery controller or a few capacitors likely could have managed the "power surges" as well.
Just curious if it can be learned online or you rather need to join a company to get the basics.
PS: I'm asking because for example in Software that was a really amazing exprience, to learn in a team. Although I had a good background. Don't think the knowledge can be learned from books or from some tutorials.
I'm sure most software people will be horrified how much "safety critical software" in modern cars and aircrafs is autogenerated based on something drawn up in Simulink/Stateflow.
These languages bring a lot of key guarantees that you can't (easily) get from more classical languages like bounded memory usage, hard real time guarantees, numerical properties, ability to prove theoretical properties about the model etc...
It's also not like having your code written as a text file would save you from using closed source proprietary compilers or languages (Ada, Ferrocene, various C distributions) for safety-critical software.
https://en.wikipedia.org/wiki/AUTOSAR
From my understanding it's very prevalent in automotive to generate microcontroller code.
Of course, if you've seen hardware products designed by mostly software teams, same sorta issues, but on the hardware side.
It's hard to fault them for reaching for a powerful core when they have the kitchen sink worth of high-bandwidth sensors on the thing, including 4 cameras and a LIDAR.
But the nice thing of 6-legged robots and such, is that to make them at the "hobby" level you don't even need to be an expert in those fields; knowing one well and then the basics of the other two is enough to follow tutorials and build it! And it's also a lot of fun and I'd recommend anyone with a small interest to try it. I created one of those with a couple of friends, in a much rougher way (but it worked!) in a couple of days.
One jack-of-all trades engineer could for sure do both, but in larger projects with high budget (BD, NASA rovers, etc), you'd have even more different specializations just in mechanical engineering: thermals, structural analysts, motorization experts, etc.
I really miss it. Reading this made me jealous of these guys, they look like they are having a lot of fun. I wonder: is it possible to do a competition like this for fun, somewhere in the US? Is anyone working on something like this purely on a recreational basis? Is there some kind of club I can join? I know about student competitions e.g. AUVSI but I'm not allowed to do those without academic status.
Like, flexible plastic solids with tension wires ('tendons') embedded in tubes. Let an AI figure out how to pull them to create locomotion.
That took only a few seconds to think of. I'd love to see that tried.