Design of a fractional-order sliding mode controller for lane- keeping in autonomous driving

An improved fractional-order integral sliding mode control (FOISMC) method is proposed in this study to address the performance degradation of lane-keeping control for intelligent vehicles under complex conditions. In this approach, a fractional-order integral sliding surface is constructed by introducing a composite tracking error e, and is combined with an improved fractional-order variable power reaching law to design a lane-keeping controller based on FOISMC. Subsequently, the Lyapunov stability theory is employed to analyze the system's stability, and a proof is provided to demonstrate that the system states can reach the fractional-order integral sliding surface in finite time. Finally, a co-simulation model was established using MATLAB/Simulink and CarSim to evaluate the proposed control strategy. The results demonstrate that, even under high-speed conditions with crosswind disturbances, the FOISMC outperforms both TISMC and FOPID. Specifically, the maximum lateral position error is reduced by 10.1% and 68.7%, respectively, while the root mean square error is decreased by 8% and 60.9%. These results confirm that the proposed approach not only achieves a significant improvement in control accuracy but also exhibits strong robustness.