Merge pull request google-deepmind#124 from alberthli:new-leap-hand

PiperOrigin-RevId: 703538497
Change-Id: I84f1db2ca4bb503f514e5c3cfddc63c531b3d699

Author: copybara-github

leap_hand/README.md

@@ -5,30 +5,67 @@
 
 ## Overview
 
-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/leap-hand/LEAP_Hand_Sim/blob/master/assets/leap_hand/robot.urdf).
+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).
 
 <p float="left">
-  <img src="leap_hand_left.png" width="400">
-  <img src="leap_hand_right.png" width="400">
+  <img src="right_hand.png" width="400">
 </p>
 
 ## URDF → MJCF derivation steps
 
-1. Added `<mujoco> <compiler discardvisual="false" strippath="false" fusestatic="false" balanceinertia="true"/> </mujoco>` to the URDF's
-   `<robot>` clause in order to preserve visual geometries.
-2. Removed `package://` shortcuts in the URDF.
-3. Loaded the URDF into MuJoCo and saved a corresponding MJCF.
-4. Manually edited the MJCF to extract common properties into the `<default>` section.
-5. Added `exclude` clause to prevent collisions between the palm and the base of each finger as well as the mcp and dip joint of each finger.
-6. Added position controlled actuators.
-7. Added `impratio=10` and `cone=elliptic` for better noslip.
-8. Added `scene.xml` which includes the robot, with a textured groundplane, skybox, and haze.
-
-Extra steps taken for the left hand:
-
-- Renamed `palm_lower_left` to `palm_lower`.
-- Replaced `thumb_left_temp_base` mesh with `pip` to match the right hand.
-- Reordered the joints of the thumb to match that of the right hand.
+### Right Hand
+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)
+2. Run it through drake's fix_inertia tool (v. 1.30.0)
+3. Add the following mujoco block to the urdf under `<robot>`:
+    ```
+    <mujoco>
+      <compiler balanceinertia="true" discardvisual="false" fusestatic="false"/>
+    </mujoco>
+    ```
+4. Open the file in the mujoco viewer using
+    ```
+    python -m mujoco.viewer --mjcf=<name_of_inertia_fixed_urdf>.urdf
+    ```
+5. Save the xml out of the viewer by clicking the "Save xml" button. From now on, modifications are referring to the saved xml.
+6. Delete the auxiliary body "base" created by not fusing static bodies.
+7. Rename bodies and joints according to the following:
+    - palm_lower -> palm
+    - mcp_joint -> base
+    - pip -> proximal
+    - dip -> medial
+    - fingertip -> distal
+    - white_tip -> tip
+8. Give names to all geoms according to visual or collision status.
+9. Create default classes for joints and assign all joints to their appropriate class.
+10. Delete the actuatorfrcrange field for all joints.
+11. Add actuators for all the joints.
+12. Add collision filters.
+13. Create the visual default group + add the material black.
+14. Adjust actuator defaults and solref to increase realism of joints.
+15. Use the implicitfast integrator, elliptic friction cone, and high impratio.
+16. Create a geom class default for fingertips with high friction.
+17. Delete unnecessary "tip_head" bodies.
+18. Simplify the fingertip meshes using open3d:
+    ```
+    import open3d as o3d
+
+    mesh = o3d.io.read_triangle_mesh("tip.obj")
+    mesh_smp = mesh.simplify_quadric_decimation(target_number_of_triangles=100)
+    o3d.io.write_triangle_mesh("tip_smp.obj", mesh_smp)
+
+    mesh = o3d.io.read_triangle_mesh("thumb_tip.obj")
+    mesh_smp = mesh.simplify_quadric_decimation(target_number_of_triangles=100)
+    o3d.io.write_triangle_mesh("thumb_tip_smp.obj", mesh_smp)
+    ```
+    Replace the old obj files with the simplified ones.
+19. Add sensors for each of the fingers.
+20. Change the "pos" field of "thumb_mp_collision" to "-0.0075 -0.0002 -0.011" in
+    order to fix incorrect orientation of thumb collision geometry.
+
+### Left Hand
+The steps for creating the left hand are mostly the same, except for the following:
+- we use the `dexsuite` hash `6eeda17435d46dde5915a16fd37b248bd8bb468e`, because there are edits for making the left handed LEAP URDF more consistent with the right
+- there was no correction of the "thumb_mp_collision" field, but the associated visual mesh is different (thumb_mp_left.obj)
 
 ## License