Yuval Tassa
4278c7b0cd
Every mechanical attribute read in MJCF now derives from mjcf.schema. generate_read_table.py emits typed mjXAttr rows (mjcf_read_table.inc, doc_test-gated) binding each attribute to its spec struct field; field offsets are offsetof() expressions, so binding mistakes are compile errors, and the field's C type -- parsed from the headers -- selects the row kind, so mjtNum-versus-double is decided by the struct, not the schema. mjXReader::ReadAttrTable is the generic loop; its static core also serves the section parsers and records XML-authored fields via mjs_setAuthored for attach conflict resolution. Row kinds cover strings, string lists, numeric scalars and vectors (exact and ranged), enums (int- and byte-width), bitwise flag sets, bools, unbounded typed vectors, fixed char arrays, and identity constants declared by 'set'. The rows are inline variables, and carry the writing=custom flag, because the writer will share them. The keyword maps the rows reference are generated too: the ~48 hand-written mjMap tables become mjcf_map.h, one map and size constant per enum as C++17 inline variables, retiring the hand-maintained extern block in xml_base.h. Map names follow the schema enum names (fluid->fluidshape, TFAuto->FalseTrueAuto, FAuto->FalseAuto, joint->jointtype, geom->geomtype, jac->jacobian); all maps are key-order- and value-identical to the hand tables they replace, and bool_map is hand-emitted (the bool type is built in, not a schema enum). The OneX() parsers reduce to genuine irregulars, schema-marked as reading=custom: orientation alternatives, file attributes (VFS and asset-dir context), the actuator shorthand remappings and per-type input maps, springlength's one-value copy, mesh builtin construction, hfield elevation, texture cube files, flexcomp seeding, the memory suffix parse, and the flag bit families. All 41 sensors that are pure identity-plus-references -- including the frame family and insidesite -- dispatch through a generated tag table; frame-sensor objtype/reftype vocabulary tightens from the full mju_str2Type namespace to the documented body/xbody/geom/site/camera subset, so an invalid keyword now fails at parse time instead of compile time. The equality family and both tendon types read shared group rows; the twelve actuator shorthands share the general rows, with per-tag legality enforced by the schema check. Sections bind non-mjs structs, the visual sub-sections reaching their anonymous sub-structs through member paths declared by an element-level field= facet. Latent irregularities surfaced by the migration and preserved via schema declarations or remnants: key's name is set even when absent, eulerseq and gridlayout are fixed char arrays (chars[n], arity in characters), gridlayout's length-must-match-gridsize stays a value-conditional remnant, and constructor-style elements (tendon wraps, asset model, replicate, attach) are annotated as such -- their attributes are arguments, not field writes. Two coherence tests guard the schema against the C sources: every schema enum constant must be a member of the C enum it claims, and every C member must be a keyword, a count sentinel, or a documented exemption; and generate_default_table.py emits one row per defaulted attribute (mjcf_default_table.inc), compared by SchemaDefaultsTest against a freshly-constructed spec -- the schema cannot disagree with the C default-constructors without failing the suite. Verified: doc_test regenerates and diffs every artifact; the full suite; and an A/B harness compiling the model corpus against the pre-migration reader -- saved XML and binary models are byte-identical. PiperOrigin-RevId: 958075724 Change-Id: I9715fe4deeb438eec988fd5084d74ba8b466b10b
MuJoCo stands for Multi-Joint dynamics with Contact. It is a general purpose physics engine that aims to facilitate research and development in robotics, biomechanics, graphics and animation, machine learning, and other areas which demand fast and accurate simulation of articulated structures interacting with their environment.
This repository is maintained by Google DeepMind.
MuJoCo has a C API and is intended for researchers and developers. The runtime simulation module is tuned to maximize performance and operates on low-level data structures that are preallocated by the built-in XML compiler. The library includes interactive visualization with a native GUI, rendered in OpenGL. MuJoCo further exposes a large number of utility functions for computing physics-related quantities.
We also provide Python bindings and a plug-in for the Unity game engine.
Documentation
MuJoCo's documentation can be found at mujoco.readthedocs.io. Upcoming features due for the next release can be found in the changelog in the "latest" branch.
Getting Started
There are two easy ways to get started with MuJoCo:
-
Run
simulateon your machine. This video shows a screen capture ofsimulate, MuJoCo's native interactive viewer. Follow the steps described in the Getting Started section of the documentation to getsimulaterunning on your machine. -
Explore our online IPython notebooks. If you are a Python user, you might want to start with our tutorial notebooks running on Google Colab:
- The introductory tutorial teaches MuJoCo basics:
- The Model Editing tutorial shows how to create and edit models procedurally:
- The rollout tutorial shows how to use the multithreaded
rolloutmodule: - The LQR tutorial synthesizes a linear-quadratic controller, balancing a
humanoid on one leg:
- The least-squares tutorial explains how to use the Python-based nonlinear
least-squares solver:
- The MJX tutorial provides usage examples of
MuJoCo XLA, a branch of MuJoCo written in JAX:
- The differentiable physics tutorial trains locomotion policies with
analytical gradients automatically derived from MuJoCo's physics step:
Installation
Prebuilt binaries
Versioned releases are available as precompiled binaries from the GitHub releases page, built for Linux (x86-64 and AArch64), Windows (x86-64 only), and macOS (universal). This is the recommended way to use the software.
Building from source
Users who wish to build MuJoCo from source should consult the build from
source section of the documentation. However, note that the commit at
the tip of the main branch may be unstable.
Python (>= 3.10)
The native Python bindings, which come pre-packaged with a copy of MuJoCo, can be installed from PyPI via:
pip install mujoco
Note that Pre-built Linux wheels target manylinux2014, see
here for compatible distributions. For more
information such as building the bindings from source, see the Python bindings
section of the documentation.
Versioning
We aim to release MuJoCo in the first week of each month. Our versioning standards changed to modified Semantic Versioning in 3.5.0, see versioning for details.
Contributing
We welcome community engagement: questions, requests for help, bug reports and feature requests. To read more about bug reports, feature requests and more ambitious contributions, please see our contributors guide and style guide.
Asking Questions
Questions and requests for help are welcome as a GitHub "Asking for Help" Discussion and should focus on a specific problem or question.
Bug reports and feature requests
GitHub Issues are reserved for bug reports, feature requests and other development-related subjects.
Related software
MuJoCo is the backbone for numerous environment packages. Below we list several bindings and converters.
Bindings
These packages give users of various languages access to MuJoCo functionality:
First-party bindings:
- Python bindings
- dm_control, Google DeepMind's related environment stack, includes PyMJCF, a module for procedural manipulation of MuJoCo models.
- JavaScript bindings and WebAssembly support (inspired stillonearth and zalo's community projects; mjswan extends these with real-time policy control, interactive force application, and more).
- C# bindings and Unity plug-in
Third-party bindings:
- MATLAB Simulink: Simulink Blockset for MuJoCo Simulator by Manoj Velmurugan.
- Swift: swift-mujoco
- Java: mujoco-java
- Julia: MuJoCo.jl
- Rust: MuJoCo-rs
Converters
- OpenSim: MyoConverter converts OpenSim models to MJCF.
- SDFormat: gz-mujoco is a two-way SDFormat <-> MJCF conversion tool.
- OBJ: obj2mjcf a script for converting composite OBJ files into a loadable MJCF model.
- onshape: Onshape to Robot Converts onshape CAD assemblies to MJCF.
Citation
If you use MuJoCo for published research, please cite:
@inproceedings{todorov2012mujoco,
title={MuJoCo: A physics engine for model-based control},
author={Todorov, Emanuel and Erez, Tom and Tassa, Yuval},
booktitle={2012 IEEE/RSJ International Conference on Intelligent Robots and Systems},
pages={5026--5033},
year={2012},
organization={IEEE},
doi={10.1109/IROS.2012.6386109}
}
License and Disclaimer
Copyright 2021 DeepMind Technologies Limited.
Box collision code (engine_collision_box.c)
is Copyright 2016 Svetoslav Kolev.
ReStructuredText documents, images, and videos in the doc directory are made
available under the terms of the Creative Commons Attribution 4.0 (CC BY 4.0)
license. You may obtain a copy of the License at
https://creativecommons.org/licenses/by/4.0/legalcode.
Source code is licensed under the Apache License, Version 2.0. You may obtain a copy of the License at https://www.apache.org/licenses/LICENSE-2.0.
This is not an officially supported Google product.