Incorporating Moving Horizon Estimation into Koopman Model Predictive Control for Autonomous Vehicle Path Tracking
摘要
As a data-driven modeling approach, the Koopman operator theory captures nonlinear characteristics of electromechanical systems (e.g., vehicles) more accurately than physics-based methods. In this paper, we employ the Extended Dynamic Mode Decomposition (EDMD) algorithm to extract basis functions for the Koopman operator, mapping the nonlinear vehicle system dynamics into a linear representation in a lifted space. The selection of basis functions for state lifting is crucial in Koopman-based model identification. Therefore, we conduct a comparative study of several typical basis functions and investigate the impact of basis function dimensionality on model accuracy. Additionally, a Moving Horizon Estimation (MHE) model is introduced to accurately predict lateral vehicle velocity when direct measurement is challenging. The proposed model is then applied to predict vehicle states over a prediction horizon, forming a constrained finite-time optimal control problem under the Model Predictive Control (MPC) framework, termed MHE-KMPC. Simulation results under three lane-change scenarios using a CarSim/Simulink co-simulation platform demonstrate that the proposed MHE-KMPC achieves higher tracking accuracy and enhanced real-time performance compared to both linear and nonlinear MPC benchmarks.