Each mjEQ_FLEXSTRAIN equality now represents a single cell within a flex. This allows for more efficient sparse Jacobian computation by only considering the degrees of freedom of the nodes within each specific cell. This change gives a speedup of about 10x on a 3x3x3 model.
PiperOrigin-RevId: 902164069
Change-Id: I78eedf1d5cf39b8989fe9863c22d164922fc0efb
The flex interpolation stiffness matrix within the implicit/implicitfast solvers is now built and factorized in a banded format instead of a dense one. This involves:
- Calculating the bandwidth based on the sparsity of the mass/damping matrix and the connectivity within flex cells.
- Allocating and populating a banded matrix `H`.
- Using `mju_cholFactorBand` and `mju_cholSolveBand` for factorization and solving.
This change improves performance for flexes with many DOFs but local coupling.
PiperOrigin-RevId: 901297952
Change-Id: I3efe06353d1903ea65ab30dc49685cede228bb68
This change introduces a `flex_cellcount` field to `mjModel` to specify the number of cells in each dimension for interpolated flexes. The stiffness computation, passive force calculation, and Jacobian derivatives are updated to operate on a per-cell basis, significantly improving performance by localizing computations to the nodes within each cell.
PiperOrigin-RevId: 901216393
Change-Id: Ic23132e609de11e71bb7fef8d1f139daad2ec264
This change introduces `nflexstiffness` and `flex_stiffnessadr` to allow flex stiffness matrices to have sizes other than the fixed 21 per element. Higher-order flexes can now store larger stiffness matrices based on their number of nodes. The `flex_stiffnessadr` array provides the starting index for each flex's stiffness data within the `flex_stiffness` array.
PiperOrigin-RevId: 899632263
Change-Id: Ie49182c46c3777acf0c6b492345edfcf62fb5e44
This default forces users to use the `spec.assets` dictionary or to do other filepath gymnastics when loading URDF. Instead we encourage users to just modify file paths directly if necessary.
PiperOrigin-RevId: 899009853
Change-Id: I4bb84606a95b65be79ccc77ccbe78062d6de8773
This removes the need to load these decoders via mj_loadAllPluginLibraries when using MuJoCo built with CMake. Other plugins are unchanged.
PiperOrigin-RevId: 897114719
Change-Id: Iee914cc5e05798186f384a67901f1cf86bc2f887
- Remove `lugre:viscous`, should now be added directly to actuator `damping`. Trying to do this for the user was incompatible with default inheritance (compounding instead of overriding).
- Move voltage limiting from the `saturation` to the `controller` attribute.
- Fix indexing issues in default inheritance.
PiperOrigin-RevId: 897087642
Change-Id: I5388c2633e15c7e223992e7eb5d6a28db75a6438
Previously on MSVC we used DllMain to register plugins, you cannot have multiple definitions of DllMain in a single unit so you would get errors if you tried to register two plugins. This modifies the implementation to insert a function pointer into the C runtime initialization instead.
PiperOrigin-RevId: 896612678
Change-Id: I07732147b955d741c836acff6da986db0e9b9eff
Add a new mjpEncoder plugin type mirroring the existing mjpDecoder pattern.
Encoders serialize an mjSpec + mjModel to an mjResource for a given format.
New API functions:
- mjp_registerEncoder: globally register an encoder
- mjp_defaultEncoder: zero-initialize an encoder struct
- mjp_findEncoder: look up an encoder by filename extension or content type
The mjfEncode callback takes (mjSpec*, mjModel*, mjVFS*, mjResource*) and
returns 0 on success. Writing to mjResource keeps symmetry with the decoder
reading from mjResource and leaves the door open for writable resource providers.
PiperOrigin-RevId: 889187898
Change-Id: I180771b2255b91dea188ac5e2cdc3a8f0fb85364
The `vertcollide` attribute in flex and flexcomp contact specifications has been removed since the next mjWarp release will support flex collisions. This attribute was previously used to enable vertex-based collisions by adding sphere geoms at flex vertices. The functionality associated with this attribute has been deprecated and removed from the XML parser, documentation, and internal data structures. Affected example XML files have also been updated.
PiperOrigin-RevId: 885595503
Change-Id: I6a78975f1bc540c09ea8b5306ff3be0962b7ab24
*** Reason for rollback ***
Rolling back obj/stl decoder inclusion as sources due to broken windows build.
*** Original change description ***
Include obj and stl decoder plugins as sources in CMake builds.
This removes the need to load these decoders via mj_loadAllPluginLibraries when using MuJoCo built with CMake. Other plugins are unchanged.
***
PiperOrigin-RevId: 885576586
Change-Id: I31e6fa4d10697862f7d800d0d771ca752747e36d
This removes the need to load these decoders via mj_loadAllPluginLibraries when using MuJoCo built with CMake. Other plugins are unchanged.
PiperOrigin-RevId: 885555524
Change-Id: I20aa5b6c55b678398345d49cb1c47667ae2bebcf
This change improves trilinear flex elements by using reduced integration for volumetric quantities (strain trace and volume ratio) at the element center, while adding full integration for shear components at 8 Gauss points and removing the second strain invariant from the constraints, which is negligible for small strains. This reduced integration "B-bar" technique is standard in finite element analysis and prevents artificial stiffness that can occur when low-order elements are nearly incompressible. The constraint count per trilinear element changes from 24 to 26 compared to using invariants. For quadratic elements, the full 27 quadrature point are used resulting in 162 constraints.
PiperOrigin-RevId: 884570752
Change-Id: Ib74ece8f4712c2c81fbfd784524fcac52a2c80e5
The next release will include breaking changes, so this bumps the major
version to reflect that.
PiperOrigin-RevId: 881351265
Change-Id: I970c68a0211651c07fcb8109ebd0b138196cf50a
Yuval Tassa