Approximate non-linear model predictive control with safety-augmented neural networks

Fuente: arXiv
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Autori principali: Hose, Henrik, Köhler, Johannes, Zeilinger, Melanie N., Trimpe, Sebastian
Natura: Preprint
Pubblicazione: 2023
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author Hose, Henrik
Köhler, Johannes
Zeilinger, Melanie N.
Trimpe, Sebastian
author_facet Hose, Henrik
Köhler, Johannes
Zeilinger, Melanie N.
Trimpe, Sebastian
contents Model predictive control (MPC) achieves stability and constraint satisfaction for general nonlinear systems, but requires computationally expensive online optimization. This paper studies approximations of such MPC controllers via neural networks (NNs) to achieve fast online evaluation. We propose safety augmentation that yields deterministic guarantees for convergence and constraint satisfaction despite approximation inaccuracies. We approximate the entire input sequence of the MPC with NNs, which allows us to verify online if it is a feasible solution to the MPC problem. We replace the NN solution by a safe candidate based on standard MPC techniques whenever it is infeasible or has worse cost. Our method requires a single evaluation of the NN and forward integration of the input sequence online, which is fast to compute on resource-constrained systems. The proposed control framework is illustrated using two numerical non-linear MPC benchmarks of different complexity, demonstrating computational speedups that are orders of magnitude higher than online optimization. In the examples, we achieve deterministic safety through the safety-augmented NNs, where a naive NN implementation fails.
format Preprint
id arxiv_https___arxiv_org_abs_2304_09575
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Approximate non-linear model predictive control with safety-augmented neural networks
Hose, Henrik
Köhler, Johannes
Zeilinger, Melanie N.
Trimpe, Sebastian
Systems and Control
Machine Learning
Optimization and Control
Model predictive control (MPC) achieves stability and constraint satisfaction for general nonlinear systems, but requires computationally expensive online optimization. This paper studies approximations of such MPC controllers via neural networks (NNs) to achieve fast online evaluation. We propose safety augmentation that yields deterministic guarantees for convergence and constraint satisfaction despite approximation inaccuracies. We approximate the entire input sequence of the MPC with NNs, which allows us to verify online if it is a feasible solution to the MPC problem. We replace the NN solution by a safe candidate based on standard MPC techniques whenever it is infeasible or has worse cost. Our method requires a single evaluation of the NN and forward integration of the input sequence online, which is fast to compute on resource-constrained systems. The proposed control framework is illustrated using two numerical non-linear MPC benchmarks of different complexity, demonstrating computational speedups that are orders of magnitude higher than online optimization. In the examples, we achieve deterministic safety through the safety-augmented NNs, where a naive NN implementation fails.
title Approximate non-linear model predictive control with safety-augmented neural networks
topic Systems and Control
Machine Learning
Optimization and Control
url https://arxiv.org/abs/2304.09575