Robust Nonlinear Control Using Barrier Lyapunov Function under Lateral Offset Error Constraint for Lateral Control of Autonomous Vehicles

In this study, we propose a robust nonlinear control method using the barrier Lyapunov function (BLF) under the lateral offset error constraint for lateral control of autonomous vehicles. Furthermore, for the application of the BLF-based control method to lateral control, we propose a second-order lateral dynamics scheme based on the look-ahead distance of the vehicle. In the second-order lateral dynamics, the system functions with unknown parameters, and the external disturbances can be lumped into a disturbance term. The proposed method consists of an extended state observer (ESO) and a nonlinear controller. The ESO is designed to estimate the full state variable and disturbance, including the system modeling and external disturbance. The nonlinear controller is developed using the BLF to compensate for the disturbances and to guarantee the constraint for the lateral offset error. Consequently, the proposed method satisfies the output constraint in the presence of disturbances and modeling uncertainties as well as improves the lateral control performance using only the lateral offset error at the look-ahead distance. The lateral control performance of the proposed method is validated using CarSim and MATLAB/Simulink.