Drake Documentation

The ConstraintSolver is a prototype solver for mixed linear complementarity problems (MLCPs) designed for rigid multi-body systems. It handles bilateral and unilateral constraints, as well as polyhedral approximations of friction cone constraints.

Warning: This solver is currently located within an example and is not a supported main Drake feature. It is known to perform poorly for real robotic applications due to numerical ill-conditioning and lack of scalability with the number of constraints. It is intended for research or illustrative purposes rather than production robotics.

Drake provides several benchmarking programs to measure the performance of multibody operations and specific algorithms:

• acrobot: Benchmarks plant operations under autodiff to detect performance regressions.
• cassie: A medium-sized robot benchmark used to measure mass matrix, inverse dynamics, forward dynamics, and their AutoDiff derivatives. It is intended for local performance measurement and code tweaking rather than regression testing.
• iiwa_relaxed_pos_ik: A benchmark specifically for InverseKinematics.
• position_constraint: A benchmark for PositionConstraint.

Drake v0.14.0 introduces several improvements to multibody dynamics:

• ABA Integration: MultibodyPlant::DoCalcTimeDerivatives() now uses the Articulated Body Algorithm (ABA).
• Contact Properties: Added support for parsing Drake contact material properties via SDFormat/URDF.
• Collision Filtering: URDF parsing now supports collision filter groups.
• Frame Registration: All MultibodyPlant bodies now have a registered geometry frame.
• Force Construction: You can now construct MultibodyForces before constructing a MultibodyPlant.
• Visualization: Added support for ellipsoid rendering, textures for primitive objects (in RenderEngine*), and Graphviz visualization of MultibodyPlant topology.

Drake uses a rolling release model rather than SemVer. New stable versions (numbered 1.x.y) are released approximately once per month.

Key stability concepts:

• Rolling Deprecation Window: When a feature is deprecated, it is typically finalized and removed 3+ minor versions later. This provides a roughly 3-month notice window.
• Deprecation Announcements: Announcements are made in the release notes.
• Language Warnings: C++ uses [[deprecated]] and Python uses warnings.warn to highlight changes, though these may not catch every instance.
• Upgrade Recommendation: It is recommended to upgrade your pinned version of Drake at least every 3 months to stay ahead of deprecations.

The Drake website is built using Jekyll. The following directory structure is relevant for managing or extending the website content:

• doc/assets/: Static assets (CSS, JS).
• doc/doxygen_cxx/: C++ API reference.
• doc/images/: Images.
• doc/_includes/: Jekyll include components (via Liquid). These can render Markdown.
• doc/_layouts/: Jekyll HTML layouts. These cannot render Markdown.
• doc/_pages/: Jekyll collection for additional root-level pages. These can render Markdown.
• doc/pydrake/: Python API reference.
• doc/_release-notes/: Jekyll collection containing the index of versioned releases.
• doc/styleguide/: External Drake Style Guide.
• doc/third_party/: Third party assets.
• doc/index.md: The home page.

v1.55.0 introduces several updates to Multibody Dynamics:

• Inactive proximity geometry: Support for 'inactive' proximity geometry in collision filters.
• Meshcat deformables: The Meshcat visualizer now supports deformables.
• CENIC joint locking: CENIC now supports joint locking.
• Bug Fixes: Fixed scalar converting MultibodyPlant vis-a-vis DeformableModel, CENIC constraint handling for small time steps, and eliding identity frames in joint parsing.

Dynamical Systems

• Added systems::sensors::OptitrackReceiver.
• systems::framework::BasicVector and systems::DiscreteValues now include value methods that return VectorX.
• DiagramBuilder now fails-fast if used after the Build() method is called.

Mathematical Program

• Added IrisInConfigurationSpace with Ibex geometry optimization.
• Added GetGraphvizString to GraphOfConvexSets.

Multibody Dynamics and Geometry

• Added several Meshcat visualizers: MeshcatPointCloudVisualizer, MeshcatContactVisualizer, and recording methods for MeshcatVisualizerCpp.
• Added Meshcat primitives: SetLine, SetLineSegments, SetTriangleMesh, and SetObject(TriangleSurfaceMesh).

Miscellaneous

• Added improved support for reading and writing YAML-serialized files.
• All package URIs within Drake's publicly accessible data now use the package://drake/... prefix.

Dynamical Systems

• DiagramBuilder::Disconnect: New method added to disconnect components.
• SimulatorConfig::start_time: Added start_time to the simulator configuration.

Mathematical Program

• OSQP: The OSQP solver now always reports primal and dual values regardless of the solver status.

Multibody Dynamics and Geometry

• Added point-to-specific-geometries distance query.

Planning

• Added JointLimits active DoF selecting constructors.

pydrake (Python bindings)

• Added binding for CollisionFilterScope.
• Added binding for DofMask operator [].

Drake's directory structure is designed to prevent circular dependencies. The logical dependency order is:

1. Core Libraries: The foundation of the repository.
2. drake/examples: Logically follows all core libraries.
3. test directories: Located throughout the code, these are logically last and are allowed to depend on any other directory (including examples), provided the dependency is explicitly declared in the build system rules.