Experimental Validation of String Stability for Connected Vehicles Subject to Information Delay

In this paper, we investigate the performance of communication-based controller design in connected vehicle networks. A testbed consisting of a group of ground robots that can mimic the dynamics of personal vehicles is built. We show that when incorporating time delays in the modeling equations, which arise due to digital implementation and intermittent vehicle-to-vehicle (V2V) communication, the experimental results have a very good correspondence with the theoretical ones. Moreover, we demonstrate that by designing a controller for each individual vehicle in the chain plant stability and string stability can be guaranteed despite the time delays in the control loop. Then, a series of experiments is conducted for a mixture of string stable and string unstable vehicles and the effects of penetration rate of string stable vehicles in maintaining smooth traffic are evaluated. The results lay a foundation for connected vehicle system design with flexible connectivity topologies.