Learning Changes the World and Then What Was Learned has Changed: Training and Deploying Neural Networks in the Control Loop

Abstract:Neural networks offer critical adaptability for controlling complex systems where nominal modeling proves intractable. However, when offline-trained neural networks are deployed within closed-loop control systems, their actions fundamentally alter the state distribution upon which they were trained. This paper introduces a unified taxonomy to categorize these sequential failure modes: the initial Closed-Loop Identification Error, the deployment-induced Action Error, and the continuous Tracking Error. Through discrete-time sensitivity analysis, this work formalizes how offline-learned parameters locally guarantee a trajectory divergence upon deployment, degrading performance due to local loss geometry. To mitigate this distribution shift, we propose actionable design policies centered on time-scale separated online adaptation. These mechanisms are validated through ablation studies on a nonlinear Duffing oscillator, demonstrating that bounded continuous learning successfully mitigates trajectory divergence whereas static deployments fail, offering concrete guidelines for practitioners deploying machine learning components in safety-critical feedback systems.

Machine Learning (stat.ML); Machine Learning (cs.LG)

arXiv:2610.22084 [stat.ML]

(or arXiv:2610.22084v1 [stat.ML] for this version)

https://doi.org/10.48550/arXiv.2610.22084 arXiv-issued DOI via DataCite (pending registration)

(Lippi, 2026) In Proc. of the 23rd Int. Conf. on Informatics in Control, Automation and Robotics - Vol. 1, ISBN 978-989-758-870-9, ISSN 2184-2809, pp 15-26