chenlin/Mujoco_WASM
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

New SDF objective function.

Browse Source 
This solves the jittery behavior observed with the gear example in the case of small applied torques (~0.5).

The new quadratic option has the form max(A, 0)^2/2 + max(B, 0)^2/2 - min(A, 0)*min(B, 0). This function has a minimum in the intersections of two SDFs A and B, while avoiding the flat areas which would be generated if only the clearance field A+B were employed. See for example [the function resulting from two colliding circles](https://www.wolframalpha.com/input?i=minimize+max%28sqrt%28x%5E2%2By%5E2%29-1%2C0%29%5E2+%2B+max%28sqrt%28%28x-1%29%5E2%2B%28y-1%29%5E2%29-1%2C0%29%5E2+-+2*min%28sqrt%28x%5E2%2By%5E2%29-1%2C0%29*min%28sqrt%28%28x-1%29%5E2%2B%28y-1%29%5E2%29-1%2C0%29)

PiperOrigin-RevId: 583992855
Change-Id: I135a1b5931cd136d7d33cc275f8d361a8b7e290c
This commit is contained in:
Alessio Quaglino
2023-11-20 05:05:42 -08:00
committed by Copybara-Service
parent 98082ae7f9
commit dbf44fe2b4
4 changed files with 44 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files
doc/programming/extension.rst
+1 -1
View File
@@ -269,7 +269,7 @@ Currently, there are three directories of first-party plugins:
<https://github.com/google-deepmind/mujoco/blob/main/plugin/sdf/README.md>`__. The rest of this section will give more
detail concerning the collision algorithm and the plugin engine interface.
Collision points are found by minimizing the maximum of the two colliding SDFs via gradient descent.
Collision points are found by minimizing a quadratic form of the two colliding SDFs via gradient descent.
Because SDFs are non-convex, multiple starting points are required in order to converge to multiple local minima.
The number of starting points is set using :ref:`sdf_initpoints<option-sdf_initpoints>`, and are
initialized using the Halton sequence inside the intersection of the axis-aligned bounding boxes.