Fault tolerancy in Cooperative Adaptive Cruise Control

Future mobility requires sound solutions in the field of fault tolerance in real-time applications amongst which Cooperative Adaptive Cruise Control (CACC). This control system cannot rely on the driver as a backup and is constantly active and therefore more prominent to the occurrences of faults (such as packet loss in the wireless communication). This paper presents an algorithm which uses the availability of sensor-data in each moment in time to calculate in real-time a safe distance for the CACC system. This safe distance consists of a velocity dependent part and a constant part, both important settings in the spacing policy for the CACC. A critical scenario for which CACC should still be functional is chosen, mathematical models of the system response are derived and errors are modeled. The model enables the calculation of differences in braking distances, which leads to a required safe distance. This approach makes the dynamic algorithm useful for sensor faults. The algorithm is implemented in a test vehicle and test results are presented.