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Stanford Pupper: low-cost quadruped robot

stanfordstudentrobotics.org

41–50 of 79 posts

Re: Stanford Pupper: low-cost quadruped robot

#42

Should I build this or spot micro? https://www.thingiverse.com/thing:3445283

The SpotMicroAI project has a great community on its Slack, but the project is a bit more in its infancy than Pupper. For instance, spot micro doesn't have the software right now to make it walk quickly or trot. Pupper is at a v1.0 stage with software and build instructions already complete, but it's potentially more expensive to build than spot micro.

Any idea how much the spot micro would cost?

I’d enjoy working on the software to make it walk.

Re: Stanford Pupper: low-cost quadruped robot

#43
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Re: Stanford Pupper: low-cost quadruped robot

#44
post #20

Earlier quoted context omitted.

https://github.com/XRobots/miniDogV2 The code's a bit of a mess -- James is clearly not a software engineer first. This is totally understandable, given that he does so many other things! When I first saw the code, I thought about doing a refactoring pass and making a pull request. It would be painful to test correctness without the hardware, and I don't want to make things worse, so I haven't.

Oh wow, you're not joking. I'm getting flashbacks to when I supported a team of EEs.

Hell, I'm getting flashbacks to my own code in EE lab. Except this stuff looks way less messy, not nearly enough random assembly declarations to bludgeon a register or pin into submission.

Re: Stanford Pupper: low-cost quadruped robot

#45
post #8

> You can buy most of the parts directly from a reseller like Amazon or McMaster-Carr, but for some you’ll need to get them custom manufactured for you. The custom parts include the carbon fiber routed parts, the 3D printed parts, the power distribution printed circuit board, and the motors. Very cool and I would like to build this, but the "Nano Dog" is probably a cheaper and more approachable option for the garage…

the parts list for the puppet is a joke everything is overkill for no reason you could easily do it for 200 same size and function

Re: Stanford Pupper: low-cost quadruped robot

#46

Should I build this or spot micro? https://www.thingiverse.com/thing:3445283

I don’t want to talk bad about anyone’s project. This is the first time I’m seeing both of these projects and the Stanford Pupper looks a lot more promising.

My heuristic is the following: Legged robotics is hard. Four legged robots are even harder than six legged ones. Using hobby servos makes the task even harder. You can find a lot of succesfull hexapod projects with hobby servos but up until fairly recently no four legged ones.

These robots operate in a very thight spot of the design space. The motors have to be fast enough to be responsive, but torquey enough to bear the dynamic loads. The mechanism has to be compliant enough to not overstress the gears but not too springy lets the robot collapse into a mess. The structure has to be rigid enough to support the forces, but also light enough so the legs can carry it. All in all designing a four legged walking robot with hobby servos is a hard problem. It is very easy to put together something which looks like a dog robot and even easier to feel that once the hardware is there from then on it is only a software problem to make it walk. For many possible designs that is false. Not even the best software could make them work.

This is what i know about the problem space. And then I look at the spot micro. It looks awesome. Clearly they made it to mime the spot mini robot. The problem is that all that is superflous. It is a design fetish. Maybe they put in all the effort to design the right leg lengths and the appropriate springyness and carefully considered the torque and thermal limits of those servos and come to the conclusion that they can afford the extra grams. But it is more likely that they did none of that and just made the 3d drawings look cool.

If you build the Stanford Pupper you will eventually probably end up with a walking robot. The video where they show it perform on the stage is a pinacle of a lot of tweaking and design work. I just don’t see the same about the spot micro.

Re: Stanford Pupper: low-cost quadruped robot

#49
post #8

> You can buy most of the parts directly from a reseller like Amazon or McMaster-Carr, but for some you’ll need to get them custom manufactured for you. The custom parts include the carbon fiber routed parts, the 3D printed parts, the power distribution printed circuit board, and the motors. Very cool and I would like to build this, but the "Nano Dog" is probably a cheaper and more approachable option for the garage…

the parts list for the puppet is a joke everything is overkill for no reason you could easily do it for 200 same size and function

I've built several servo powered walking robots. Torque is a major concern, and obviously weight plays a part in how much torque is required. The recommended servos look to be $30 each, x12 means $360. If you spent $200 just on servos you'd have to settle for $16 servos. Probably less torque. That would mean that at full leg extension the robot might not be able to support itself. That would be an annoyance when trying to focus on walking algorithm development, which is usually the fun part for these small walkers.

You can definitely do something for cheaper, but I wouldn't call this a joke. When I was 15 (20 years ago lol) I designed an 18 servo hexapod. I saved up $350 from cleaning horse stalls and my dad agreed to pay the other half, and I spent $700 on servos. It was great to learn about inverse kinematics before ever setting foot on a college campus!

Re: Stanford Pupper: low-cost quadruped robot

#50
post #23

For about the same price, you can build a "spot micro" [1] if you have a 3D printer. I haven't build one myself (yet) but it's been fun following them. I came across them when someone in HN posted how to train it using OpenGym (will find the link when I'm not on mobile). [1] https://gitlab.com/custom_robots/spotmicroai

Do you happen to have a video of the spot micro actually walking? I can’t seem to find any. It is easy to make a spot shaped object. Making it walk is the hard part.

You got me curious. A direct search on youtube nets this:

https://www.youtube.com/watch?v=pRCBEaGtxuU and this: https://www.youtube.com/watch?v=tW3fp6nHbqk

But it would be nice to see some more advance walking.

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