Vehicle Platoon String Stability: Network Passivity Approach

Control of large interconnected systems with different interconnection topologies has primarily been tackled using decentralized control. An implementation of decentralized control is in string stability of interconnected systems with applications to vehicle following. In this paper, the use of passivity formalism as a means to analyse string stability in vehicle platoons is proposed. In order to employ passivity, network theory is used to model the interconnection topology of the vehicle platoon system. A bidirectional vehicle platoon, modelled by linear dynamics under constant distance spacing, employing linear controllers is used as a case study. With this in mind, we show that any arbitrary length bidirectional platoon can be modelled as a combination of a cascade of two-port networks coupled to a one-port network. Consequently, the stability of the coupled system can be analysed using passivity theory. The work is supported by theoretical and numerical analysis.