Model-Based Reinforcement Learning via Stochastic Hybrid Models

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openAccess

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Volume Title

A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2023

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Mcode

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Language

en

Pages

16
155-170

Series

IEEE Open Journal of Control Systems, Volume 2

Abstract

Optimal control of general nonlinear systems is a central challenge in automation. Enabled by powerful function approximators, data-driven approaches to control have recently successfully tackled challenging applications. However, such methods often obscure the structure of dynamics and control behind black-box over-parameterized representations, thus limiting our ability to understand closed-loop behavior. This paper adopts a hybrid-system view of nonlinear modeling and control that lends an explicit hierarchical structure to the problem and breaks down complex dynamics into simpler localized units. We consider a sequence modeling paradigm that captures the temporal structure of the data and derive an expectation-maximization (EM) algorithm that automatically decomposes nonlinear dynamics into stochastic piecewise affine models with nonlinear transition boundaries. Furthermore, we show that these time-series models naturally admit a closed-loop extension that we use to extract local polynomial feedback controllers from nonlinear experts via behavioral cloning. Finally, we introduce a novel hybrid relative entropy policy search (Hb-REPS) technique that incorporates the hierarchical nature of hybrid models and optimizes a set of time-invariant piecewise feedback controllers derived from a piecewise polynomial approximation of a global state-value function.

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Keywords

Hidden Markov models, Switches, Behavioral sciences, Bayes methods, Stochastic processes, Nonlinear dynamical systems, Reinforcement learning

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Citation

Abdulsamad, H & Peters, J 2023, ' Model-Based Reinforcement Learning via Stochastic Hybrid Models ', IEEE Open Journal of Control Systems, vol. 2, 10128705, pp. 155-170 . https://doi.org/10.1109/OJCSYS.2023.3277308