Alessio Quaglino
f9f1db1e0a
with a preconditioned Conjugate Gradient (CG) solver that operates on the full system matrix. The previous approach extracted flex DOFs into a reduced banded system, factored it separately, and overwrote the global solve. This required precomputed bandwidth (makeFlexBandwidth), parent-joint detection, coupling corrections, and a FlexInterpContext struct — and only worked for standalone flex trees without parent joints. The new CG solver uses the already-factored global system (M - h*qDeriv) as a preconditioner and adds the flex stiffness contribution via matrix-free products (mjd_flexInterp_mulKD/mulK). This handles any kinematic configuration — including flexes attached to articulated chains or with parent joints — without sparsity pattern restrictions. Before (`bunny_multicell`): ``` Simulation time : 50.80 s Steps per second : 197 Realtime factor : 0.20 x Time per step : 5080.3 µs CG iters / step : 3.16 Contacts / step : 31.04 Constraints / step : 124.15 Degrees of freedom : 178 Dynamic memory usage : 0.4% of 100M ``` After: ``` Simulation time : 9.52 s Steps per second : 1051 Realtime factor : 1.05 x Time per step : 951.7 µs CG iters / step : 3.21 Contacts / step : 30.90 Constraints / step : 123.61 Degrees of freedom : 178 Dynamic memory usage : 0.3% of 100M ``` PiperOrigin-RevId: 913758038 Change-Id: If5aa617b2d535c86aec9bd71c9e0003a2b38bdd7
43 lines
1.4 KiB
XML
43 lines
1.4 KiB
XML
<!-- Copyright 2024 DeepMind Technologies Limited
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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<mujoco model="Trilinear">
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<include file="scene.xml"/>
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<option solver="CG" tolerance="1e-6" integrator="implicitfast"/>
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<size memory="10M"/>
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<visual>
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<map stiffness="100"/>
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</visual>
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<worldbody>
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<body>
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<joint name="press" type="slide" axis="0 0 1" damping="500"/>
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<geom type="box" size=".02 .2 .2" pos="0 0 .5"/>
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</body>
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<flexcomp type="mesh" file="bunny.obj" pos="0 0 0" dim="2" euler="90 0 0" cellcount="3 3 3"
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radius=".001" rgba="0 .7 .7 1" mass=".05" name="softbody" dof="trilinear">
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<elasticity young="1e3" poisson="0.1" damping="0.01" elastic2d="none"/>
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<contact selfcollide="none" internal="false"/>
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</flexcomp>
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</worldbody>
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<actuator>
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<position name="press" joint="press" gear="-1 0 0 0 0 0" ctrlrange="-1 1" kp="1000"/>
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</actuator>
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</mujoco>
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