Recursively Feasible Probabilistic Safe Online Learning with Control Barrier Functions

Fuente: arXiv
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Main Authors: Castañeda, Fernando, Choi, Jason J., Jung, Wonsuhk, Zhang, Bike, Tomlin, Claire J., Sreenath, Koushil
Format: Preprint
Published: 2022
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author Castañeda, Fernando
Choi, Jason J.
Jung, Wonsuhk
Zhang, Bike
Tomlin, Claire J.
Sreenath, Koushil
author_facet Castañeda, Fernando
Choi, Jason J.
Jung, Wonsuhk
Zhang, Bike
Tomlin, Claire J.
Sreenath, Koushil
contents Learning-based control has recently shown great efficacy in performing complex tasks for various applications. However, to deploy it in real systems, it is of vital importance to guarantee the system will stay safe. Control Barrier Functions (CBFs) offer mathematical tools for designing safety-preserving controllers for systems with known dynamics. In this article, we first introduce a model-uncertainty-aware reformulation of CBF-based safety-critical controllers using Gaussian Process (GP) regression to close the gap between an approximate mathematical model and the real system, which results in a second-order cone program (SOCP)-based control design. We then present the pointwise feasibility conditions of the resulting safety controller, highlighting the level of richness that the available system information must meet to ensure safety. We use these conditions to devise an event-triggered online data collection strategy that ensures the recursive feasibility of the learned safety controller. Our method works by constantly reasoning about whether the current information is sufficient to ensure safety or if new measurements under active safe exploration are required to reduce the uncertainty. As a result, our proposed framework can guarantee the forward invariance of the safe set defined by the CBF with high probability, even if it contains a priori unexplored regions. We validate the proposed framework in two numerical simulation experiments.
format Preprint
id arxiv_https___arxiv_org_abs_2208_10733
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Recursively Feasible Probabilistic Safe Online Learning with Control Barrier Functions
Castañeda, Fernando
Choi, Jason J.
Jung, Wonsuhk
Zhang, Bike
Tomlin, Claire J.
Sreenath, Koushil
Systems and Control
Machine Learning
Optimization and Control
Learning-based control has recently shown great efficacy in performing complex tasks for various applications. However, to deploy it in real systems, it is of vital importance to guarantee the system will stay safe. Control Barrier Functions (CBFs) offer mathematical tools for designing safety-preserving controllers for systems with known dynamics. In this article, we first introduce a model-uncertainty-aware reformulation of CBF-based safety-critical controllers using Gaussian Process (GP) regression to close the gap between an approximate mathematical model and the real system, which results in a second-order cone program (SOCP)-based control design. We then present the pointwise feasibility conditions of the resulting safety controller, highlighting the level of richness that the available system information must meet to ensure safety. We use these conditions to devise an event-triggered online data collection strategy that ensures the recursive feasibility of the learned safety controller. Our method works by constantly reasoning about whether the current information is sufficient to ensure safety or if new measurements under active safe exploration are required to reduce the uncertainty. As a result, our proposed framework can guarantee the forward invariance of the safe set defined by the CBF with high probability, even if it contains a priori unexplored regions. We validate the proposed framework in two numerical simulation experiments.
title Recursively Feasible Probabilistic Safe Online Learning with Control Barrier Functions
topic Systems and Control
Machine Learning
Optimization and Control
url https://arxiv.org/abs/2208.10733