Hierarchical steering control for a front wheel drive automated car

In this study the lateral control of an automated vehicle is analysed with the help of a single-track model while subject to a hierarchical control algorithm. At the higher-level we command the steering angle based on the vehicle's relative position and orientation to the desired path, while the lower-level controller tries to achieve this angle by adjusting the steering torque. The stability of the straight-line motion is investigated by incorporating time delays at both control levels. We demonstrate that the two control algorithms can be designed independently from each other. Moreover, we show that the stability of the lower-level controller is highly sensitive to the delay, that is, to ensure stability very high sampling frequency is required.