86 lines
3.5 KiB
Markdown
86 lines
3.5 KiB
Markdown
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# Leap Hand Description (MJCF)
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> [!IMPORTANT]
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> Requires MuJoCo 3.1.3 or later.
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## Overview
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This package contains a simplified robot description (MJCF) of the (left and right) [LEAP Hand](https://leaphand.com/) developed by Carnegie Mellon University. It is derived from the [publicly available URDF description](https://github.com/dexsuite/dex-urdf/tree/main/robots/hands/leap_hand).
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<p float="left">
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<img src="right_hand.png" width="400">
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</p>
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## URDF → MJCF derivation steps
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### Right Hand
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1. Start with the right-handed LEAP hand URDF from [dexsuite (hash: 2ee2f70cfd549857f56ffe13c61fa939f4cb50ba)](https://github.com/dexsuite/dex-urdf/tree/main/robots/hands/leap_hand)
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2. Run it through drake's fix_inertia tool (v. 1.30.0)
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3. Add the following mujoco block to the urdf under `<robot>`:
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```
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<mujoco>
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<compiler balanceinertia="true" discardvisual="false" fusestatic="false"/>
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</mujoco>
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```
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4. Open the file in the mujoco viewer using
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```
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python -m mujoco.viewer --mjcf=<name_of_inertia_fixed_urdf>.urdf
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```
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5. Save the xml out of the viewer by clicking the "Save xml" button. From now on, modifications are referring to the saved xml.
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6. Delete the auxiliary body "base" created by not fusing static bodies.
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7. Rename bodies and joints according to the following:
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- palm_lower -> palm
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- mcp_joint -> base
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- pip -> proximal
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- dip -> medial
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- fingertip -> distal
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- white_tip -> tip
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8. Give names to all geoms according to visual or collision status.
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9. Create default classes for joints and assign all joints to their appropriate class.
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10. Delete the actuatorfrcrange field for all joints.
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11. Add actuators for all the joints.
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12. Add collision filters.
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13. Create the visual default group + add the material black.
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14. Adjust actuator defaults and solref to increase realism of joints.
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15. Use the implicitfast integrator, elliptic friction cone, and high impratio.
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16. Create a geom class default for fingertips with high friction.
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17. Delete unnecessary "tip_head" bodies.
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18. Simplify the fingertip meshes using open3d:
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```
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import open3d as o3d
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mesh = o3d.io.read_triangle_mesh("tip.obj")
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mesh_smp = mesh.simplify_quadric_decimation(target_number_of_triangles=100)
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o3d.io.write_triangle_mesh("tip_smp.obj", mesh_smp)
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mesh = o3d.io.read_triangle_mesh("thumb_tip.obj")
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mesh_smp = mesh.simplify_quadric_decimation(target_number_of_triangles=100)
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o3d.io.write_triangle_mesh("thumb_tip_smp.obj", mesh_smp)
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```
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Replace the old obj files with the simplified ones.
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19. Add sensors for each of the fingers.
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20. Change the "pos" field of "thumb_mp_collision" to "-0.0075 -0.0002 -0.011" in
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order to fix incorrect orientation of thumb collision geometry.
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### Left Hand
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The steps for creating the left hand are mostly the same, except for the following:
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- we use the `dexsuite` hash `6eeda17435d46dde5915a16fd37b248bd8bb468e`, because there are edits for making the left handed LEAP URDF more consistent with the right
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- there was no correction of the "thumb_mp_collision" field, but the associated visual mesh is different (thumb_mp_left.obj)
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## License
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This model is released under an [MIT License](LICENSE).
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## Publications
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The LEAP Hand is described in the following publication:
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```bibtex
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@article{shaw2023leaphand,
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title = {LEAP Hand: Low-Cost, Efficient, and Anthropomorphic Hand for Robot Learning},
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author = {Shaw, Kenneth and Agarwal, Ananye and Pathak, Deepak},
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journal = {Robotics: Science and Systems (RSS)},
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year = {2023}
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}
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```
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