[HN Gopher] Open-sourcing the MuJoCo physics simulator for robotics
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Open-sourcing the MuJoCo physics simulator for robotics
Author : stokaasto
Score : 278 points
Date : 2021-10-18 15:20 UTC (7 hours ago)
(HTM) web link (deepmind.com)
(TXT) w3m dump (deepmind.com)
| whinvik wrote:
| A little off topic but is there a good library for physics
| simulations that involve cloth modeling.
| alhirzel wrote:
| Does anyone know how this compares to e.g. Chrono?
|
| https://github.com/projectchrono/chrono
| rg111 wrote:
| MuJoCo is _the_ standard in much of robotics, and recently in the
| Deep RL space.
|
| When I was learning Deep RL, I edged on what could be done
| through OpenAI gym, or self-made environments, I decided to begin
| working with MuJoCo.
|
| But for an undergrad student from a developing country, the fees
| were extremely high.
|
| So, I just didn't go forward with Deep RL much. I dabbled for a
| while and tried using PyBullet. Did not go that well.
|
| Also thought about creating custom environments in Unity and then
| apply Deep RL in there. But it took too much effort.
|
| Creating a complex enough environment and getting used to it
| were, in themselves- full projects that took long term
| commitment.
|
| As a result, I did not learn much Deep RL to be able to apply it
| to complex, real-world-like scenarios.
|
| I think that it is going to change.
|
| I am excited about books, blogs, and videos that are going to be
| created as MuJoCo is open-sourced and available for free.
|
| I, personally, will get back into Deep RL the next opportunity I
| get.
| TaylorAlexander wrote:
| I similarly did not get in to using MuJoCo because I want all
| my work to be reproducible with open source. So I spent time
| trying to get RL working in Godot video game engine, but ran in
| to some road blocks. I know MuJoCo already has all the
| necessary pipelines so this is exciting indeed!
| 5faulker wrote:
| It would still be a while that we achieve emergence (if that's
| even possible) anyway, so time is kind of on our side.
| EvgeniyZh wrote:
| Pretty sure it had free educational license tho
| rg111 wrote:
| My uni was not rich enough to have an email server for
| students.
|
| So, I did not have a uni mail address.
|
| That was required.
| okay475008 wrote:
| go to literally any college you can probably walk to one
| near you if you live in a city, sign up for a basic
| program, and get a free email address. sounds dumb, but if
| you sign up to talk an extra language you'll have your
| email address you so desperatly need in your life
| CryingSofa wrote:
| Somewhat. The free educational license was only acceptable
| for 'personal' projects, so not suitable for class work.
| Jeff_Brown wrote:
| Surely that kind of use would have been fine. What they're
| trying to do with that questionnaire must be to determine
| if you're making money from the venture. You can share your
| diary with others and still call it personal, after all.
| (Once you get a publisher involved, not so much.)
| amelius wrote:
| > MuJoCo is a second-order continuous-time simulator,
| implementing the full Equations of Motion
|
| Are there any books describing how to implement this kind of
| physics engine?
| siekmanj wrote:
| This is an amazing outcome. The license cost was a huge barrier
| to entry and the progress of deep RL generally.
| KaoruAoiShiho wrote:
| Is this a competitor to physX?
| 6gvONxR4sf7o wrote:
| Nope. PhysX is all about realtime and gaming is the end use it
| was designed around. TFA has a section about why that's bad.
| The different end uses mean there are miles of differences
| between them even though they're both physics simulators.
| Voloskaya wrote:
| A lot of RL problems can be adequately simulated in either
| Mujoco or PhysX. So even though as you pointed out they have
| key differences, there is a pretty big overlap in use cases.
| So in that sense, I believe it still does qualify as
| competition.
| 6gvONxR4sf7o wrote:
| I have personally spent tons of time dealing with models
| exploiting physics issues. It's a major issue. It's true
| that either can adequately simulate the setups, but is it
| true that either can be equally exploited? I genuinely
| don't know. I kinda assumed physx is more exploitable.
| Voloskaya wrote:
| I agree with you that PhysX is definitely easier to
| exploit, and you will lose time because of that.
|
| But on the other hand, for many problems, the gain in
| training time using PhysX is just so massive (2 or 3
| orders of magnitude), that you can then train with a much
| more aggressive sim2real policy to mitigate that to some
| extent, or even spend time debugging manually and still
| ending up more productive.
| tiborsaas wrote:
| What kind of exploits are you talking about? Cheating in
| games for example?
| [deleted]
| hacoo wrote:
| I think this is referring to inaccuracies of simulation
| which the RL model can learn to exploit. Sort of a local
| minimum that doesn't exist in the real world.
| atty wrote:
| I tend to be more than a little skeptical of organizations like
| DeepMind and (especially) OpenAI lately, when it comes to their
| pledges to democratize their advances in AI/ML/robotics. This,
| however, is 100% a great move by DeepMind in the support of the
| community as a whole. Kudos to the team, and a big thanks as
| well.
| querez wrote:
| Pretty sure this was just a reaction to losing so much
| mindshare to Brax since that came out.
| nmca wrote:
| Brax is dope, but it's a long long way from feature parity
| with MuJoCo, which is world class.
| Permit wrote:
| My understanding is that DeepMind did not previously own
| MuJoCo, but today they have acquired it and released it for
| free.
|
| On the other hand, Brax is developed by Google and is written
| using Jax (which DeepMind loves and uses extensively).
|
| Why would DeepMind have been concerned that people were
| switching to Brax?
| querez wrote:
| Good point, I was not aware that Deepmind aquired MuJoCo
| recently.
| cepher wrote:
| I wonder what this means for the future of Brax [1].
|
| 1. https://github.com/google/brax
| cyber_kinetist wrote:
| Google Research already maintains the Bullet Engine as well
| (although it mostly seems to be Erwin Coumans maintaing it)
|
| Each have their own strengths, there is no "definitive" physics
| engine. Bullet is probably the most generalist engine, but it
| suffers a bit because of this approach (it's split between the
| old 2.0 C++ API vs. the new PyBullet API with vastly different
| functionalities)
| amelius wrote:
| Can it do fluid simulations for aquatic robots?
| modeless wrote:
| Great news! It was a real issue that so much RL research relied
| on non-free software. It was a problem that a big pile of money
| could solve, so I'm glad someone with a big pile of money did :)
| notesonbots wrote:
| sfdsdf
| AlexCoventry wrote:
| You should favorite it, if you want to leave a placeholder on
| it. It's a link near the top of the thread.
| [deleted]
| a-dub wrote:
| interesting. will they be including any biomechanical models as
| part of the open sourced stuff?
| [deleted]
| jefft255 wrote:
| This is really good news. It was a really contentious issue in RL
| and robotics research to be so reliant on proprietary (and very
| expensive) software.
| asah wrote:
| +1 - plus, it's an immediate barrier for attracting new people
| to the field.
| klowrey wrote:
| There was a free license for individual users, with the non-
| free license applicable to those who were receiving financial
| support (i.e. academic / industry researchers, etc.). The
| individual license was very popular and heavily utilized.
| minimaxir wrote:
| For more context on "very expensive," a MuJoCo license was
| _several hundreds of dollars_.
| GistNoesis wrote:
| For reference here is the price before as seen on november
| 2020 (previous internet archive screenshot), https://web.arch
| ive.org/web/20201111235930/https://www.robot...
|
| TLDR: personal non commercial 500$/year for usage on up to 3
| computers personal commercial 2000$/year
| cyber_kinetist wrote:
| For undergrad students trying to dabble in reinforcement
| learning, several hundreds of dollars can be quite a lot.
| dekhn wrote:
| as an undergrad in the 90s I invested thousands of dollars
| of my own money to work on machine learning. Worth every
| penny, even if I had to miss out on some cool parties.
| regularfry wrote:
| Wonderful that you had thousands of dollars as an
| undergrad to be able to do so.
| dekhn wrote:
| Worked a job to pay for ram. It atypical.
| NikolaeVarius wrote:
| Working in undergrad isn't a common thing?
| cdcarter wrote:
| Well, if you're working to pay your rent, bills, and food
| expenses, and you're only working part time (because
| you're a full time undergraduate student), you may not
| have a lot left over to pay for software licenses.
| dekhn wrote:
| which is precisely the reason I went with linux: so I
| could maximize my hardware resources while eliminating
| license costs. By not buying whatever MS compiler in
| those days, I was able to max out my workstation with
| 32MB RAM.
| regularfry wrote:
| Working in undergrad and having thousands left over after
| paying for food and a place to sleep certainly can't be
| assumed to be. That's where my pay went.
| xwolfi wrote:
| But they can accept that the world is not geared towards
| amateur dabblers, and that a few hundreds of $ for a
| license (a license, meaning to legalize production usage,
| you can always copy from somewhere to "dabble") is nothing.
| [deleted]
| Syntonicles wrote:
| Well now they don't have to, because it really is
| nothing.
| ResearchCode wrote:
| The CS world has certainly been geared towards the
| hobbyist budget for some time now. Would be good to keep
| it that way, even if it meant sacrificing a supposed 1%
| extra accuracy in the latest "top conference" (sure if
| their sponsors are the companies publishing huge models
| it won't happen even if it should).
| gautamcgoel wrote:
| I wish someone would do this for MATLAB.
| zokier wrote:
| It seems great, but the simulation geometry options feel bit
| limited? What would be really great would be the ability to
| simulate scenes with objects imported from STEP/IGES files, so
| you can do more of the modeling in actual CAD tools. Instead,
| MuJoCo seems more oriented towards using its own primitives, not
| sure how that works out with more complex situations.
| bionhoward wrote:
| This is huge for the open source ML community because so many
| academic and commercial projects rely on MuJoCo which is out of
| reach for folks working on hobby projects or at tiny startups.
| This makes a lot more AI environments work for everyone. Major
| props to DeepMind
| [deleted]
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