Verify the source of implicit excitation in closed-loop control

Verify whether future control actions selected by the improved cross-entropy method provide implicit excitation through their execution and incorporation into the rolling inference context, thereby explaining the strong closed-loop performance observed from initially unexcited contexts.

Background

The paper reports that predictors can perform well in closed-loop control even when the initial context contains no deliberate excitation. The authors hypothesize that the control actions chosen by the improved cross-entropy method subsequently enter the rolling context and thereby create informative variation for the predictive model. This mechanism is contrasted with the deterministic model-predictive-control trajectories used in the open-loop experiments, which do not involve learning or inference dynamics. Directly verifying whether this rolling-context mechanism produces the observed performance remains unresolved.

References

Surprisingly, even when the initial context at the start of an episode is unexcited, the performance is good. We hypothesize that this arises because future control actions selected by \ac{iCEM} are subsequently executed and enter the rolling context, thereby providing implicit excitation. In contrast, the data used as \ac{MPC} context in the open-loop experiments is generated by a deterministic \ac{MPC}, with no learning or inference dynamics. Verifying this mechanism directly is left for future work.

— Time-series Foundation Models for Predictive Control: The Role of Excitation  (2610.06447 - Amria et al., 5 Oct 2026) in Section 4.3, “Preliminary Closed-Loop Evaluation”

More broadly, our results suggest that context is a central design variable for \ac{TSFM}-based control: how to retain control-informative observations and how much excitation is required for reliable input-output identification remain open questions.

— Time-series Foundation Models for Predictive Control: The Role of Excitation  (2610.06447 - Amria et al., 5 Oct 2026) in Section 5, “Conclusion”