Stanford Pupper: low-cost quadruped robot

> the "Nano Dog" is probably a cheaper and more approachable option for the garage engineer.

Hard to find out much about that or OpenDog in general. I've found videos and 3d printer files but nothing that I can read to understand what it can do and why I might want to build it.

Or do I really have to watch a bunch of YouTube videos? I hate video.

Have I missed the actual project page somehow?

For carbon fiber parts (used for the chassis and legs), I wonder if it is possible to carve them out out from the same power distribution PCB board. Some PCB manufacture seems to support custom shapes.

But the PCB material must be heavier than carbon fiber, not sure if it will affect the robot dynamics.

I wasn't able to find any examples of this quadruped walking.

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

But is a different project for a bigger and more expensive design.

Here is a GitHub link to the actual Pupper project: https://github.com/stanfordroboticsclub/StanfordQuadruped and not to Stanford Doggo.

Awesome project! I'd love to build one, except for sourcing the parts - esp. the carbon fibre (out-of-stock) bits! If your team sold it as a kit I'd be your first customer! Of course, you'd have to ship to Canada too.

Q. Was there a price point you had to aim for in the development (i.e. under $1K)? And, if you were to double the price, what improvements would you make (e.g. even better servos)?

Awesome project Nathan, kudos to the team. I'd love to use the Stanford Pupper at some point for K-12 outreach efforts myself.

I reviewed your power distribution board. I think it needs more safety features before it can safely be entrusted to the hands of K-12 kids. Couple of comments:

- The battery input is unfused. I would HIGHLY recommend adding one.

- I know you guys wrote in Github about how people should not plug in voltages above 8.4V, and not overdischarge batteries, but I would not trust K-12 kids to follow those instructions :)

It would be best to add a overvoltage, overcurrent and reverse polarity protection circuits. Those are pretty simple and should not take much space on the board. Jerri Ellisworth has a great video where she explains these circuits in detail, and how to make them low-cost: https://www.youtube.com/watch?v=QZ0WXQWND-I

- I would add a schmitt trigger circuit to sense the battery voltage and feed that as a digital input to the Raspberry Pi. If the batteries are too low, the Pi then can throw an audible alarm and disable the servos. This would prevent kids from overdischarging their batteries.

As a future addition, I think it would be sweet to add a Teensy somewhere. Then students would be able to easily add extra sensors and have their robot respond to changes in the environment etc. So much potential for fun.

Congrats again!

Great project, thanks!

Is Pupper in any way related to this quadraped robot here [1] — or do they just have a similar looking physical architecture?

[1] https://www.youtube.com/watch?v=bnEtJSkUFDk

We've found you can actually do a lot with dumb servos and orientation feedback and get visually similar results to Spot. For instance, we get hopping, trotting, strafing, turning + strafing, walking. What it can't do is prancing or a flying trot. But we think it's totally worth it since a good-enough servo is around $20, while similarly sized torque-controllable servo (excluding dynamixels, which don't actually have torque control), runs about $400 each. DJI did actually come out recently with their M3508 and M2006 which we're starting to play with, and we think we can build a torque-controllable pupper for about $1.5k.

The main limitation I think for servo robots with kinematic (position-control) controllers is speed. We're moving around 0.8m/s max, while the new Unitree A1 is something like 3.5m/s.

Is it really a vacation if you have to pencil in fun time?

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.

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.

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.

Sure, but you don’t personally need the CNC. All you need is to know somebody who is in that 1%. Or have access to a makerspace with that CNC.

You can buy the carbon fiber parts here! https://great3d.com/stanford-pupper-robot-carbon-fiber-parts...

But can it be trained to bounce or balance on a rubber ball?

https://youtu.be/FI0T0Oj7WFE

There seem to be two versions of the Bandai Smartpet Robot Dog on Amazon, one in black for $157 (that's out of stock at the moment) and one in white for $60. I don't know why there's such a high price difference, especially since there doesn't seem to be any functional difference between the two.

People always imagine that mobile robotics needs nanosecond response times or some other silliness when the reality is that your sensors and servos only operate on the order of 100Hz.

There's blackbird, but not sure of its current status. https://hackaday.io/project/160882-blackbird-bipedal-robot

the simple gaits are usually PIDs that integrate requested control directions and gyro data, bounded by maximum servo speed.

here's an informative youtube video that's all about quadrupedal dog-style robots.[0]

fancier gaits integrate elements that measure leg length and foot pressures.

[0]: https://www.youtube.com/watch?v=4MGZvcd0xxc

About $30 each on aliexpress. Seems like an ok deal to me.

I summed the BOM table it was just over $330 but it looks like that's just body no electronics at all... the servo arms look special/priciest but it's multiplied. I imagine the main thing for this aside from body is the brain but that looks to be shared as well

You can buy the CLS6336HV servos from JX-Servo directly for about $25 each. Usually a much better deal than on Aliexpress, Banggood etc and it's pretty easy to do. The $600 price point though assumes you have a number of things already like a RPi, lipo charger, or PS4 controller.