Cooperative Adaptive Cruise Control Algorithm with Priority Weights Assigned to Downstream Vehicles for Increased Safety

Cooperative Adaptive Cruise Control (CACC) is a connected automation vehicle subsystem that enables vehicles to platoon together in order to provide more efficient traffic flow. Due to the small gaps between vehicles in a platoon, extra care must be taken to ensure safe operations. Based on recent advances in communication and signal processing technologies, it is possible for vehicles to remain safe while communicating with multiple other vehicles. This paper proposes a dynamic “all predecessor following” (APF) feedforward controller that listens to every vehicle downstream of itself in order to maintain a safe platoon. In the proposed control strategy, each vehicle continually receives the position of every downstream vehicle, as well as the command speed of the preceding vehicle. Position errors allow it to recognize if a disturbance has taken place and how to respond to it in a proactive manner by changing the priority weight associated with the PD controller of each downstream vehicle. This APF controller ensures that the platoon stays collision free even if any vehicle in the platoon performs an unpredicted disturbance, such as a major braking action. In this work the authors demonstrate that the controller enables the vehicles behind the disturbance to remain safe and to smoothly adjust to it. This is done in simulations using a vehicle dynamics model developed from the performance of a 2013 SRX Cadillac.