Abstract-A method is presented for the longitudinal control of autonomous vehicles forming a multi-brand, ad hoc platoon. A leader and predecessor following (LPF) control architecture is known to allow string stable platooning with shorter safety gaps between vehicles as compared with predecessor following schemes. General LPF strategies, however, require the exact knowledge of spacing policies of predecessor vehicles for correctly specifying a spacing with respect to the leader. It follows that arbitrary spacing policies in ad hoc platoons prevent the applicability of classical LPF control structures. It is shown in this paper that it is possible to exploit the advantages of LPF architectures in multi-brand platoons without a priory knowledge of spacing policies of predecessors. The unknown spacing policies are replaced by a virtual one, which serves as an input to a two degree of freedom LPF controller. The resulting control structure enables the organization of ad hoc platoons consisting of vehicles with different spacing policies. Computer simulations are presented to illustrate the statements.Index Terms-Multi-brand platoons, ad hoc platoons, heterogenous platoons, string stability, adaptive spacing policy.

Our topography system is an enhancement of a standard TMS-1 corneal topograph instrument (Computed Anatomy Inc., New York, NY, USA). Topographic images are captured at a rate of 4 s(-1), allowing the recording of a series of 120 images in 30 s after a complete blink. In this prospective preliminary study 15 healthy volunteers were examined. The main outcome measures were the time profile of changes in surface regularity index (SRI), surface asymmetry index (SAI) and simulated keratometry values (K1, K2). After a blink there was a tendency for improvement in ocular surface regularity. Later trends were less clear. Our topography system makes possible the detailed evaluation of tear-film dynamics in the post-blink period. The new technique may play an important role in the diagnosis of various tear-film abnormalities; the results may also have significant implications in the planning of refractive surgeries.

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