The number of vehicles keeps boosting in recent decades, but the number of available roads does not stickily follow the boost of vehicles. Without adequate road, road capacity is almost full which may cause traffic issues such as traffic jam. To enhance road efficiency, researchers focus on maximizing the capacity of roads by reducing gap between vehicles. Adaptive Cruise Control (ACC) is one of popular ways for automatic platooning that all vehicles equip with on-board sensor. Inter-vehicle gap is thus shortened due to elimination of human response time.

To evaluate the effectiveness of platooning, the term string stability, which diminish inter-vehicle spacing error along strings, is mandatory to avoid performance degrade as size of platooning grows up. This ensures the inte...[ Read more ]

The number of vehicles keeps boosting in recent decades, but the number of available roads does not stickily follow the boost of vehicles. Without adequate road, road capacity is almost full which may cause traffic issues such as traffic jam. To enhance road efficiency, researchers focus on maximizing the capacity of roads by reducing gap between vehicles. Adaptive Cruise Control (ACC) is one of popular ways for automatic platooning that all vehicles equip with on-board sensor. Inter-vehicle gap is thus shortened due to elimination of human response time.

To evaluate the effectiveness of platooning, the term string stability, which diminish inter-vehicle spacing error along strings, is mandatory to avoid performance degrade as size of platooning grows up. This ensures the inter-vehicle spacing error is bounded if the first vehicle has bounded error, such that the platooning is scalable. Unfortunately, string stabibility is not reachable in ACC if constant inter-vehicle spacing need to be guaranteed, since preceding vehicle may not directly reflect any changing from leader, especially when the engine suffer from large actuator lag.

Cooperative Adaptive Cruise Control (CACC) is a successor of ACC with inter-vehicle communication such that all agents can observe leader status. String stability is thus reachable by following the leader status closely. Usually CACC require leader to broadcast its status in real-time to achieve the goal. This requirement is too expensive in practice. It may not even be feasible when communication channel consist latency and packet error.

The main contribution of this thesis is to relax the requirement from real-time to discrete-time communication without breaking the string stability. Therefore, bandwidth can be saved and communication flaws like delay and delivery failure can be tolerant. Overall, the robustness of whole platooning can be enhanced.