The Bias of Subspace-based Data-Driven Predictive Control

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Hauptverfasser: Moffat, Keith, Dörfler, Florian, Chiuso, Alessandro
Format: Preprint
Veröffentlicht: 2025
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author Moffat, Keith
Dörfler, Florian
Chiuso, Alessandro
author_facet Moffat, Keith
Dörfler, Florian
Chiuso, Alessandro
contents This paper quantifies and addresses the bias of subspace-based Data-Driven Predictive Control (DDPC) for linear, time-invariant (LTI) systems. The primary focus is the bias that arises when the training data is gathered with a feedback controller in closed-loop with the system. First, the closed-loop bias of Subspace Predictive Control is quantified using the training data innovations. Next, the bias of direct, subspace-based DDPC methods DeePC and $γ$-DDPC is shown to consist of two parts--the Subspace Bias, which arises from closed-loop data, and an Optimism Bias, which arises from DeePC/$γ$-DDPC's "optimistic" adjustment of the output trajectory. We show that, unlike subspace-based DDPC methods, Transient Predictive Control does not suffer from Subspace Bias or Optimism Bias. Double integrator experiments demonstrate that Subspace and Optimism Bias are responsible for poor reference tracking by the subspace-based DDPC methods.
format Preprint
id arxiv_https___arxiv_org_abs_2507_02468
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Bias of Subspace-based Data-Driven Predictive Control
Moffat, Keith
Dörfler, Florian
Chiuso, Alessandro
Systems and Control
This paper quantifies and addresses the bias of subspace-based Data-Driven Predictive Control (DDPC) for linear, time-invariant (LTI) systems. The primary focus is the bias that arises when the training data is gathered with a feedback controller in closed-loop with the system. First, the closed-loop bias of Subspace Predictive Control is quantified using the training data innovations. Next, the bias of direct, subspace-based DDPC methods DeePC and $γ$-DDPC is shown to consist of two parts--the Subspace Bias, which arises from closed-loop data, and an Optimism Bias, which arises from DeePC/$γ$-DDPC's "optimistic" adjustment of the output trajectory. We show that, unlike subspace-based DDPC methods, Transient Predictive Control does not suffer from Subspace Bias or Optimism Bias. Double integrator experiments demonstrate that Subspace and Optimism Bias are responsible for poor reference tracking by the subspace-based DDPC methods.
title The Bias of Subspace-based Data-Driven Predictive Control
topic Systems and Control
url https://arxiv.org/abs/2507.02468