Internal and String Stability Analysis for Vehicle Platooning under the MPF Topology under Communication Limitations

This thesis focuses on the analysis of internal stability and string stability of vehicle platoons under the multiple-predecessor following (MPF) topology, a configuration intended to lower the minimum employable time headway and increase road throughput. Within the scope of this thesis, stability is investigated for three important scenarios: in the presence of homogeneous delays, heterogeneous delays, and an observer-based controller. In the first scenario, it is assumed that vehicle-to-vehicle (V2V) communications cause the platoon to experience a constant homogenous time delay. The internal stability and string stability are then analyzed for two cases: when all data comes from the delayed network, and when onboard sensors are also employed, providing delay-free but limited information. A lower bound for the time headway is also proposed for both aforementioned cases. The second scenario focuses on the investigation of string stability for a very general case of heterogeneous vehicle platoons with the MPF topology. More specifically, we look at the following forms of heterogeneity: different parasitic lags, different time headways, different controller parameters, and most importantly, different communication time delays. Finding a lower bound for the time headway is also studied for this scenario. Finally, we propose a distributed observer-based controller as an alternative to the conventional proportional integral derivative (PID) controllers. This new controller can guarantee the internal and string stability of the platoon system and achieve a high platooning control performance. Furthermore, an algorithm is presented to find the minimum available value of the time headway.