Controller design for cooperative driving with guaranteed safe behavior

A shortcoming of many Cooperative Adaptive Cruise Control (CACC) schemes is the lack of a guarantee of safe vehicle behavior in a platoon, i.e., making sure that a vehicle does not collide with its preceding vehicle in case the latter performs a deceleration outside the operational range of the CACC system. To overcome that problem, this paper presents a controller design which has a Collision Avoidance (CA) functionality to guarantee safe vehicle behavior. When the vehicle is in a safe operational region, the nominal controller is applied, which can be designed independent of the CA function. However, when the nominal controller cannot guarantee a safe behavior, a predefined gradual braking strategy is imposed. Enforcing a gradual braking strategy instead of prompt full braking has the benefit that if a safety-critical situation resolves itself quickly, full braking is not applied. The controller scheme is illustrated in a simulation study, which shows that, as a result, the vehicles behave safely, even when the preceding vehicle instantly applies full braking.