An Execution-time-certified Riccati-based IPM Algorithm for RTI-based Input-constrained NMPC

Fuente: arXiv
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Main Authors: Wu, Liang, Ganko, Krystian, Wang, Shimin, Braatz, Richard D.
Format: Preprint
Published: 2024
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author Wu, Liang
Ganko, Krystian
Wang, Shimin
Braatz, Richard D.
author_facet Wu, Liang
Ganko, Krystian
Wang, Shimin
Braatz, Richard D.
contents Establishing an execution time certificate in deploying model predictive control (MPC) is a pressing and challenging requirement. As nonlinear MPC (NMPC) results in nonlinear programs, differing from quadratic programs encountered in linear MPC, deriving an execution time certificate for NMPC seems an impossible task. Our prior work \cite{wu2023direct} introduced an input-constrained MPC algorithm with the exact and only \textit{dimension-dependent} (\textit{data-independent}) number of floating-point operations ([flops]). This paper extends it to input-constrained NMPC problems via the real-time iteration (RTI) scheme, which results in \textit{data-varying} (but \textit{dimension-invariant}) input-constrained MPC problems. Therefore, applying our previous algorithm can certify the execution time based on the assumption that processors perform fixed [flops] in constant time. As the RTI-based scheme generally results in MPC with a long prediction horizon, this paper employs the efficient factorized Riccati recursion, whose computational cost scales linearly with the prediction horizon, to solve the Newton system at each iteration. The execution-time certified capability of the algorithm is theoretically and numerically validated through a case study involving nonlinear control of the chaotic Lorenz system.
format Preprint
id arxiv_https___arxiv_org_abs_2402_16186
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle An Execution-time-certified Riccati-based IPM Algorithm for RTI-based Input-constrained NMPC
Wu, Liang
Ganko, Krystian
Wang, Shimin
Braatz, Richard D.
Systems and Control
Establishing an execution time certificate in deploying model predictive control (MPC) is a pressing and challenging requirement. As nonlinear MPC (NMPC) results in nonlinear programs, differing from quadratic programs encountered in linear MPC, deriving an execution time certificate for NMPC seems an impossible task. Our prior work \cite{wu2023direct} introduced an input-constrained MPC algorithm with the exact and only \textit{dimension-dependent} (\textit{data-independent}) number of floating-point operations ([flops]). This paper extends it to input-constrained NMPC problems via the real-time iteration (RTI) scheme, which results in \textit{data-varying} (but \textit{dimension-invariant}) input-constrained MPC problems. Therefore, applying our previous algorithm can certify the execution time based on the assumption that processors perform fixed [flops] in constant time. As the RTI-based scheme generally results in MPC with a long prediction horizon, this paper employs the efficient factorized Riccati recursion, whose computational cost scales linearly with the prediction horizon, to solve the Newton system at each iteration. The execution-time certified capability of the algorithm is theoretically and numerically validated through a case study involving nonlinear control of the chaotic Lorenz system.
title An Execution-time-certified Riccati-based IPM Algorithm for RTI-based Input-constrained NMPC
topic Systems and Control
url https://arxiv.org/abs/2402.16186