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Main Authors: Shigematsu, Katsuya, Hoshino, Hikaru, Furutani, Eiko
Format: Preprint
Published: 2024
Subjects:
Online Access:https://arxiv.org/abs/2402.11648
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author Shigematsu, Katsuya
Hoshino, Hikaru
Furutani, Eiko
author_facet Shigematsu, Katsuya
Hoshino, Hikaru
Furutani, Eiko
contents This paper discusses discretization methods for implementing nonlinear model predictive controllers using Iterative Linear Quadratic Regulator (ILQR). Finite-difference approximations are mostly used to derive a discrete-time state equation from the original continuous-time model. However, the timestep of the discretization is sometimes restricted to be small to suppress the approximation error. In this paper, we propose to use the variational equation for deriving linearizations of the discretized system required in ILQR algorithms, which allows accurate computation regardless of the timestep. Numerical simulations of the swing-up control of an inverted pendulum demonstrate the effectiveness of this method. By the relaxing stringent requirement for the size of the timestep, the use of the variational equation can improve control performance by increasing the number of ILQR iterations possible at each timestep in the realtime computation.
format Preprint
id arxiv_https___arxiv_org_abs_2402_11648
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Iterative Linear Quadratic Regulator With Variational Equation-Based Discretization
Shigematsu, Katsuya
Hoshino, Hikaru
Furutani, Eiko
Systems and Control
This paper discusses discretization methods for implementing nonlinear model predictive controllers using Iterative Linear Quadratic Regulator (ILQR). Finite-difference approximations are mostly used to derive a discrete-time state equation from the original continuous-time model. However, the timestep of the discretization is sometimes restricted to be small to suppress the approximation error. In this paper, we propose to use the variational equation for deriving linearizations of the discretized system required in ILQR algorithms, which allows accurate computation regardless of the timestep. Numerical simulations of the swing-up control of an inverted pendulum demonstrate the effectiveness of this method. By the relaxing stringent requirement for the size of the timestep, the use of the variational equation can improve control performance by increasing the number of ILQR iterations possible at each timestep in the realtime computation.
title Iterative Linear Quadratic Regulator With Variational Equation-Based Discretization
topic Systems and Control
url https://arxiv.org/abs/2402.11648