Control

Hybrid Force-Position Control

Hybrid force-position control is a control scheme, formalized by Raibert and Craig in 1981, that partitions the task space into orthogonal directions, controlling position along unconstrained axes and force along axes constrained by contact. Selection matrices assign each Cartesian direction to one mode, so a robot can, for example, regulate normal force against a surface while tracking a trajectory tangential to it.

Why it matters for physical AI

Tasks like polishing, wiping, and insertion inherently mix motion and force objectives; hybrid control provides the classical template that learned contact-rich policies and compliant controllers still build upon.