closed-loop

Definition

A setup in which the system's own actions change the state it observes next, so every outcome feeds back into the following decision. The contrast is open-loop evaluation: replaying a fixed log and scoring predictions against it. Closed-loop is the harsher test, because small errors push the agent into states the logged data never covered and mistakes compound instead of averaging out. Same idea as feedback control in engineering.

Explainers using this term

• Paper walkthrough: Zetta ζ — a robot harness that repairs itself mid-execution, with the policy frozenZetta $ζ$: An Efficient Closed-Loop Embodied Harness for Self-Evolving Physical Intelligence