Maneuvering with safety guarantees using control barrier functions

Abstract

Control barrier functions (CBFs) ensure safety of controlled dynamical systems, by restricting the control inputs to render desired sets forward invariant. In this paper we propose a dynamic guidance scheme for autonomous vehicles, using CBFs to reactively generate an obstacle-free trajectory. By implementing the safety constraints on a kinematic guidance level, rather than on a lower-level control layer, we do not need to account for uncertainty in the ship dynamics explicitly. Moreover, for ships with well-proven and resilient control systems, this is an appropriate interface level, since it does not require modification of lower-level feedback control. The guidance scheme is applied to maneuvering of underactuated ships, using a virtual vessel with unicycle dynamics to trace out a feasible trajectory.