String stability of vehicle platoons

In recent years, highway capacity has become a limiting factor, regularly causing traffic jams. Obviously, the road capacity can be increased by decreasing the inter-vehicle following distance di . As a consequence, however, vehicle automation in longitudinal direction is required in order to still guarantee safety. To this end, Adaptive Cruise Control could be used, which is based on measurement of the inter-vehicle distance and the relative velocity by means of radar. It has however been shown [1] that this will amplify disturbances in upstream direction at short time gaps, causing so-called ghost traffic jams. Application of data exchange by means of wireless communication in addition, is shown to be able to attenuate these disturbances. This is called Cooperative Adaptive Cruise Control (CACC), illustrated in Figure 1 for a one-vehicle look-ahead communication structure.