SimReady Conform FET-004 Simulate Multi-Body Physics

Purpose

Use this workflow skill after FET000_CORE, FET001_BASE_NEUTRAL, and the selected FET003 rigid-body variant are already in a reasonable state and the next validation gate is FET004_BASE_NEUTRAL, FET004_BASE_PHYSX, or FET004_ROBOT_PHYSX. It repairs multibody structure: multiple existing rigid bodies, joints between them, articulation-root placement, and variant-specific PhysX requirements.

This is an authoring and repair skill, not the final validator. Work on a staged copy under the requested output directory, rerun the same FET004 validation gate after each repair stage, and stop at the first remaining FET004 validation failure that needs asset-design intent, source conversion, collider redesign, or geometry that is not already present.

Hard Constraint

Do not create new geometry to satisfy FET004.

• Do not add cubes, meshes, collider proxies, visual parts, or duplicate/split geometry solely to produce a second rigid body or a joint target.
• Do not invent a second body for RB.MB.001 when the asset contains only one real physical part.
• Do not generate collision geometry for PhysX FET004 failures. Reuse existing collider or visual geometry only, or hand back to FET003/source conversion when required geometry is missing.
• It is acceptable to author non-geometry USD physics structure, such as UsdPhysicsJoint prims, relationships, rigid-body schemas, articulation schemas, or physics attributes, but only when those opinions target existing prims that already represent real asset parts.

If an asset is a single-rigid-body prop and the selected profile documents FET004 as optional or conditional, treat FET004 as not applicable. Report that the asset satisfies prop physics through FET003 and should not be forced through FET004 unless the user supplies multibody intent or a source asset with separate body geometry.