Active Disturbance Rejection Control of Path Following Control for Autonomous Ground Vehicles

Structured uncertainties (e.g. uncertainty of tire cornering stiffness and time-varying longitudinal velocity) and unstructured uncertainties (e.g. nonlinearity of tire model, cross wind disturbance and noises from sensors) exist in the vehicle systems extensively. These uncertainties deteriorate the path following performances greatly, even lead to instabilities in some extreme situations. This paper presents an active disturbance rejection control (ADRC) scheme to deal with both structured uncertainties and unstructured uncertainties of path following control for autonomous ground vehicles (AGVs). Firstly, tracking control of both lateral displacement and yaw angle in path following control is simplified to yaw angle tracking control by constructing a new desired yaw angle. Secondly, considering both structured uncertainties and unstructured uncertainties as a generalized disturbance, an extended state observer (ESO) is employed to estimate the generalized disturbance. The estimation result is considered as a compensated control input. Thirdly, nominal control input is determined by a feedback linearization (FL) controller. Then, Combing both nominal control input and compensated control input results in the final control input. Finally, co-simulations are conducted using Matlab/Simulink and CarSim. Simulation results demonstrate that the proposed control scheme is superior to the existing two typical approaches in terms of path following performances and robustness.