This technical rigging course focuses on building advanced biped subsystems within Unreal Engine’s Control Rig, detailing the math and node logic required to execute a spline-driven spine, an automated spherical pose reader, a robust reverse foot lock setup, and essential backwards-solve pipelines for animation baking.
https://dev.epicgames.com/community/learning/courses/eNm/unreal-engine-control-rig-biped-spine-and-reverse-foot