Adaptive AFS and ESC coordinated control for intelligent vehicles based on robust NFTSMC considering tire nonlinearity

The escalating demands for software-defined vehicles have prompted advancements in automated driving, facilitating a shift toward a novel chassis domain electronics architecture equipped with control-by-wire actuators. How to bolster driving dynamics and stability performance via chassis domain control represents a significant and challenging endeavor. This article presents a novel dual-layer adaptive active front steering and electronic stability control (AFS-ESC) coordinated control architecture based on the robust nonsingular fast terminal sliding mode control (NFTSMC) method, aimed at stabilizing the vehicle and enhancing the maneuverability. Initially, the robust NFTSMC theory is rigorously derived and analyzed for uncertain nonlinear multiple input multiple output systems. It is then applied to develop yaw rate-based maneuverability and side-slip angle-based stability decision-making using vehicle and tire models with unknown nonlinearities, uncertainties, and disturbances. Additionally, an adaptive gain based on a stability index is introduced to coordinate the decision-making outcomes. Subsequently, the requisite total yaw-moment is allocated to the front wheel steering angle and wheel cylinder pressures through AFS and ESC, respectively, based on an adaptive semiempirical tire nonlinearity index. The efficacy of the proposed architecture is validated via 0.7 Hz sine with dwell tests with high, medium, and low tire-road adhesion on the hardware-in-the-loop platform, demonstrating its superior performance in stabilizing the vehicle and enhancing maneuverability compared to the robust control-based and NFTSMC-based AFS-ESC coordination, ESC, AFS, and uncontrolled cases.