mitchellspryn/UrdfSim

Workflow with unreal assets

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AndreasGronlund commented

Hi

The examples don't (as far as I can see) cover how an existing vehicle in the form of assets and blueprints can be incorporated in UrdfSim. Initially I was looking at AirSim but since I have a vehicle that 1) currently have more than 4 wheels 2) will have have a robot arm, AirSim does not fully work. For one if i reparent the blueprint of my vehicle to CarPawn in AirSim only four wheels remain and the rest fall off. The robot arm can be ignored for now, but all wheels needs to be functional.

A first step would be to only being able to set up the sensors on the main body of the vehicle. However, I don't see how I can create the UrdfSim xml-file with my own vehicle, which the is in the form of assets and blueprints (skeleton, mesh, blueprint and physics). It has a main body, joints and wheels etc... just as described in the xml-file but there are no STL-files.
So basically what I need to know is:

  1. Do I have to "rebuild" everything (materials, meshes and joints) in the XML-file or can I directly point to the blueprint of my vehicle in the PawnPath (as is done in AirSim) if I only want to set up the sensors and attach them to the correct "AttachLink" in my unreal mesh.

  2. Assume that directly linking to the blueprint in the PawnPath is not possible. What goes in to the UrdfFile, the xml-file which is pointed to in the pawn-path in the settings.json? I assume maybe the assets, but how? I do note that the enum ProceduralMeshFileType gives UNREAL_MESH. Can I just set this to be <mesh type="unreal_mesh" location="PATH_TO_THE_MESH_OF_MY_VEHICLE.asset" reverse_normals="true" scale_factor="100"/>.

  3. The joints to the wheels are already in the mesh of my vehicle but I note that the urdf xml-file contains joints to the wheels (and other parts). Do I have to put the <joint name> ... in the xml-file to the same names as the joints in my mesh file or can I skip? Assume two cases 1) just putting sensors to the main body of the mesh or 2) also want to control the vehicle.

  4. . Do I have to reparent my vehicle to UrdfBotPawn or any other class from UrdfSim? My current machine has WheeledVehicle as Parent Class.

Thanks in advance!