Safety Certified Cooperative Adaptive Cruise Control under Unreliable Inter-vehicle Communications
For developers of CACC systems, this work provides a formal safety guarantee under realistic communication imperfections, addressing a gap in prior formal methods that assumed ideal communication.
This paper addresses the safety verification of cooperative adaptive cruise control (CACC) systems under unreliable inter-vehicle communications with non-deterministic time delay and packet dropout. It formally verifies passive safety for a class of hybrid CACC systems, defining a safe control envelope that guarantees collision avoidance.
Cooperative adaptive cruise control(CACC) system provides a great promise to significantly reduce traffic congestion while maintaining a high level of safety. Recent years have seen an increase of using formal methods in the analysis and design of cooperative adaptive cruise control systems. However, most existing results using formal methods usually assumed an ideal inter-vehicle communication, which is far from the real world situation. Hence, we are motivated to close the gap by explicitly considering non-deterministic time delay and packet dropout due to unreliable inter-vehicle communications. In particular, we consider a passive safety property, which requests a vehicle to avoid any collisions that can be considered as its fault. Under the assumption that the communication delay is bounded and we know the upper bound, we then formally verify the passivity safety of a class of hybrid CACC systems. This result allows us to define a safe control envelope that will guide the synthesis of control signals. Vehicles under the CACC within the safe control envelope are guaranteed to avoid active collisions.