Decentralized real-time iterations for distributed NMPC

Journal
IEEE transactions on automatic control  
Citation
IEEE Transactions on Automatic Control (in Press): (2025)
Publisher DOI
10.1109/TAC.2025.3622000
Scopus ID
2-s2.0-105019785330
Publisher
Institute of Electrical and Electronics Engineers Inc.
This article presents a Real-Time Iteration (RTI) scheme for distributed Nonlinear Model Predictive Control (NMPC). The scheme transfers the well-known RTI approach, a key enabler for many industrial real-time NMPC implementations, to the setting of cooperative distributed control. At each sampling instant, one outer iteration of a bi-level decentralized Sequential Quadratic Programming (dSQP) method is applied to a centralized optimal control problem. This ensures that real-time requirements are met and it facilitates cooperation between subsystems. Combining novel dSQP convergence results with RTI stability guarantees, we prove local exponential stability under standard assumptions on the MPC design with and without terminal constraints. The proposed scheme only requires neighbor-to-neighbor communication and avoids a central coordinator. A numerical example with coupled inverted pendulums demonstrates the efficacy of the approach.
Subjects
alternating direction method of multipliers
decentralized optimization
distributed control
Nonlinear model predictive control
real-time iterations
DDC Class
600: Technology