FHWA Saxton Lab Project: CACC (Copperative Adaptive Cruise Control) Implementation and Field Testing

Field Test of 5 Cadillac Vehicles CACC (Cooperative Adaptive Cruise Control)

California PATH Cooperative Adaptive Cruise Control (CACC) for passenger cars: although ACC (Adaptive Cruise Control) is commercially available for many vehicle makes, it cannot be safely operated for varying traffic speed in real-world if more than two consecutive vehicles are on ACC. The following is the reason why we need CACC instead of ACC which is applicable to all vehicle types: For ACC/CACC, higher speeds will lead to longer following distances, somewhat similar to the behavior of common drivers. The ACC may be conservative or aggressive depending on the time gap setting. It is not exactly the same as a driver, however because (autonomous rather than cooperative) ACC only depends on remote sensor measurements relative to its immediate predecessor vehicle and cannot look/predict the behavior of the vehicles further forward, while an experienced driver usually looks/predicts the behaviors of several vehicles ahead. The limitation of autonomous ACC performance is the cumulative delays from the leader to the upstream of the vehicle-following string. This is the main destroyer of the string stability in vehicle following, which is the reason why higher ACC market penetration will makes traffic stability worse. CACC, on the other hand, provides prediction capability through Vehicle-to-Vehicle (V2V) communication: vehicle onboard sensor data including CAN (Control Area Network) Bus data are passed to all the vehicles behind, which is more accurate and with less time delay than driver perception. This is the reason why CACC vehicles can provide more stable car following than experienced drivers. In addition, significant differences among the drivers are eliminated.

This project will develop, field test and demonstrate passenger car CACC to be operated on public highways in mixed traffic. The CACC vehicle should be able to follow CACC vehicles, ACC vehicles and other manually driven vehicles. It will also need to handle the cut-in and cut out of other vehicles.

Presentations

FHWA Saxton Lab 5 Cadillac CACC (Cooperative Adaptive Cruise Control) Test in navy Station, Philadelphia (Video)