Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

CARA 2.0 – “I Built a Better Robot Dog”

aaedmusa.com

Post reply on HN
Print view View original

1–10 of 72 posts

Re: CARA 2.0 – “I Built a Better Robot Dog”

#3

Post by Animats »

3 DOF per leg, so it needs 12 motors and controllers. Getting that under $1000 is nice.

Here's the US$18 motor: [1] Those things are getting really cheap. He did have to rewind it, though, for more turns with thinner wire. The manufacturer mentions that you can order with "custom Kv", which means you might be able to get a different winding from the factory if you order a reasonable quantity. Especially if you tell them that makes them "robot motors".

Motor overheating might be a problem. The dog, just standing, has its motors stalled under load, converting power to heat. Drones don't do that. Temperature feedback would help if this thing has to operate for extended periods. Remember yesterday's article on humanoid robots and their cooling problems.

The motor controller is nice too, and cheap at $49. Needed fixes to the firmware, but that's not surprising at the price. High performance motor controllers used to cost about $1000.

Repurposed drone technology has done wonders for legged robots. We're not quite at the point where limb drive hardware is off the shelf, but it's way better than it used to be.

[1] https://www.xntyi.com/tyi-5008-kv335/kv400-high-speed-brushl...

Re: CARA 2.0 – “I Built a Better Robot Dog”

#4

Post by Springtime »

I like the wide layout of the site but just on a readability front on a widescreen monitor after the opening more narrow paragraphs it changes to full width text layout and those could benefit from a `columns: 2` in CSS to split them since reading long width paragraphs is a bit difficult.

Re: CARA 2.0 – “I Built a Better Robot Dog”

#5

Post by rmast »

Animats wrote: post #3

3 DOF per leg, so it needs 12 motors and controllers. Getting that under $1000 is nice. Here's the US$18 motor: [1] Those things are getting really cheap. He did have to rewind it, though, for more turns with thinner wire. The manufacturer mentions that you can order with "custom Kv", which means you might be able to get a different winding from the factory if you order a reasonable quantity. Especially if you tell t…

If you read the epilogue, they weren't able to achieve the under $1000 price goal. Total cost ended up being around $1,450. Pretty good price reduction compared to CARA 1.0 though.

Hypothetically if I were to want a quadrupedal robot to experiment with it's not an impulse buy/build, but getting closer to that point... whereas $3000+ is a hard pass (e.g. Apple Vision Pro territory).

Re: CARA 2.0 – “I Built a Better Robot Dog”

#6

Post by barrenko »

Animats wrote: post #3

3 DOF per leg, so it needs 12 motors and controllers. Getting that under $1000 is nice. Here's the US$18 motor: [1] Those things are getting really cheap. He did have to rewind it, though, for more turns with thinner wire. The manufacturer mentions that you can order with "custom Kv", which means you might be able to get a different winding from the factory if you order a reasonable quantity. Especially if you tell t…

Could I pursuade you to expand on "Repurposed drone technology has done wonders for legged robots." ? Thanks!

Re: CARA 2.0 – “I Built a Better Robot Dog”

#9

Post by pbmonster »

The jumps are pretty impressive, this thing has some power. I'd be very curious how fast you could get this dog with some reinforcement learning for a proper transverse gallop gait - and if it converges towards a gallop naturally, or if it discovers some other fast gait patterns during learning.

Depending on the max speed of the motors/legs, giving it longer foot pads might be necessary for a good gallop. Intuitively, it looks a bit... "low gear" in the videos.

Post reply on HN