  In this paper, we study how to secure the platooning of autonomous vehicles
when an unknown vehicle is under attack and bounded system uncertainties exist.
For the attacked vehicle, its position and speed measurements from GPS can be
manipulated arbitrarily by a malicious attacker. First, to find out which
vehicle is under attack, two detectors are proposed by using the relative
measurements (by camera or radar) and the local innovation obtained through
measurements from neighboring vehicles. Then, based on the results of the
detectors, we design a local state observer for each vehicle by applying a
saturation method to the measurement innovation. Moreover, based on the
neighbor state estimates provided by the observer, a distributed controller is
proposed to achieve the consensus in vehicle speed and keep fixed desired
distance between two neighboring vehicles. The estimation error by the observer
and the platooning error by the controller are shown to be asymptotically upper
bounded under certain conditions. The effectiveness of the proposed methods is
also evaluated in numerical simulations.
