An important aspect of an automated highway system design is the synthesis
of an automatic vehicle following system, Associated with automatic vehicle
following systems is the problem of the stability of a string of vehicles,
i,e,, the problem of spacing error propagation, and in some cases, amplifi
cation upstream from one vehicle to another, due to some disturbance at the
head of the string. Realistic vehicle following designs must also address
parametric uncertainties such as mass of the vehicle, aerodynamic drag, and
tire drag, The mass of the vehicle varies with the number of passengers. A
t small intervehicular separations, aerodynamic drag force changes signific
antly with the distance to be maintained, In this paper, we address the pro
blem of stability of a vehicle string in the presence of parametric uncerta
inty and present a Lyapunov-based decentralized adaptive control algorithm
to compensate for such parametric variations, We examine this direct adapti
ve control algorithm for platoon performance and parameter convergence. We
present the simulation results to demonstrate the effectiveness of the adap
tive controller.