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Improvement Details

Here we document how we improve the robot models in each of the following aspect compared with the original URDF file provided by manufacturer.

Better collision mesh​

All collision mesh are represented as stl or URDF primitives with simplified triangle meshes, i.e. fewer vertices and simpler edge connection. No self collision after loading into simulator.

Better visual mesh​

  1. Consistent mesh format. All visual mesh are converted as .obj but not dae due to the inconsistencies of dae loader. For each robot model, we also provides a glb version with visual meshes stored in glTF-2.0 format, which better support the Physically Based Rendering (PBR) material. Many simulators, such as IsaacGym and SAPIEN, can utilize the glb version to achieve superior visual results.
  2. Paint color for mesh. We paint the color of the visual mesh based on the real robot, as well as other material parameters like specular and metalic. Although these parameters are estimated by human eyes, they looks reasonable and better than no color.
  3. No material tag to specify color. The color of each visual mesh are stored in the mesh file rather without any <material> tag in the URDF. When both obj(sometimes the associated mtl) and <material> tag contains color information for a mesh, it is tricky to define which one can override the other. To avoid some conflicts, we remove all material tag in the URDF.

since different DAE loader may treat DAE differently, resulting inconsistent behavior across different URDF parser. For enhanced support of physically based rendering, every URDF file in this repository is accompanied by a GLTF version of urdf, which contains meshes in glb format, in addition to a standard urdf with obj mesh.

Better inertia and joint parameters​

Uniform URDF parsing across diverse parsers​

Standardized frame convention​

For all dexterous hands, the orientation are kept consistent across all dexterous hands. For right hand, the x-axis is forward, the y-axis the direction from litter finger to thumb, the z-axis is the direction from wrist to fingertip of middle finger.