Safe Lane-Keeping With Control Barrier Functions: From Theory to Practical Implementation

This article presents the design and analysis of a safe lane-keeping controller based on a kinematic single-track vehicle model. A control barrier function (CBF) is derived for the lane-keeping problem using geometrical considerations. This is used to design a safety filter that can be applied on top of a nominal lane-keeping controller and guarantees that the vehicle remains within the lane boundaries. The effects of applying the safety filter to the controlled vehicle are thoroughly analyzed using a series of numerical simulations and phase portraits, including changes in the global dynamics, passenger comfort, and input signals. The results are validated with experiments on a test vehicle that verify that the safety filter is able to keep the vehicle inside the lane boundaries. The results highlight the benefits of safety filters in lateral vehicle control, and can be used as a basis for the design of more complex controllers involving higher fidelity vehicle models to enhance the safety of both human-driven and automated vehicles (AVs).