Efficient move blocking strategy for multiple shooting-based non-linear model predictive control

Yutao Chen (Corresponding author), Nicolò Scarabottolo, Mattia Bruschetta, Alessandro Beghi

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Move blocking (MB) is a widely used strategy to reduce the degrees of freedom of the Optimal Control Problem (OCP) arising in receding horizon control. The size of the OCP is reduced by forcing the input variables to be constant over multiple discretization steps. In this paper, we focus on developing computationally efficient MB schemes for multiple shooting based nonlinear model predictive control (NMPC). The degrees of freedom of the OCP is reduced by introducing MB in the shooting step, resulting in a smaller but sparse OCP. Therefore, the discretization accuracy and level of sparsity is maintained. A condensing algorithm that exploits the sparsity structure of the OCP is proposed, that allows to reduce the computation complexity of condensing from quadratic to linear in the number of discretization nodes. As a result, active-set methods with warm-start strategy can be efficiently employed, thus allowing the use of a longer prediction horizon. A detailed comparison between the proposed scheme and the nonuniform grid NMPC is given. Effectiveness of the algorithm in reducing computational burden while maintaining optimization accuracy and constraints fulfillment is shown by means of simulations with two different problems.
Original languageEnglish
Pages (from-to)343-351
Number of pages9
JournalIET Control Theory & Applications
Volume14
Issue number2
DOIs
Publication statusPublished - Feb 2020

Fingerprint

Multiple Shooting
Nonlinear Model Predictive Control
Model predictive control
Optimal Control Problem
Discretization
Sparsity
Degree of freedom
Active Set Method
Receding Horizon Control
Non-uniform Grid
Shooting
Forcing
Horizon
Strategy
Optimization
Prediction
Vertex of a graph
Simulation

Keywords

  • DoFs
  • MB schemes
  • computation complexity
  • computational complexity
  • discretisation accuracy
  • efficient move blocking strategy
  • multiple discretisation steps
  • multiple shooting-based nonlinear model predictive control
  • nonlinear control systems
  • nonuniform grid NMPC
  • optimal control
  • optimal control problem
  • optimisation
  • prediction horizon
  • predictive control
  • receding horizon control
  • shooting step
  • warm-start strategy

Cite this

Chen, Yutao ; Scarabottolo, Nicolò ; Bruschetta, Mattia ; Beghi, Alessandro. / Efficient move blocking strategy for multiple shooting-based non-linear model predictive control. In: IET Control Theory & Applications. 2020 ; Vol. 14, No. 2. pp. 343-351.
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Efficient move blocking strategy for multiple shooting-based non-linear model predictive control. / Chen, Yutao (Corresponding author); Scarabottolo, Nicolò; Bruschetta, Mattia; Beghi, Alessandro.

In: IET Control Theory & Applications, Vol. 14, No. 2, 02.2020, p. 343-351.

Research output: Contribution to journalArticleAcademicpeer-review

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