4,088 research outputs found
String Stability towards Leader thanks to Asymmetric Bidirectional Controller
This paper deals with the problem of string stability of interconnected
systems with double-integrator open loop dynamics (e.g.~acceleration-controlled
vehicles). We analyze an asymmetric bidirectional linear controller, where each
vehicle is coupled solely to its immediate predecessor and to its immediate
follower with different gains in these two directions. We show that in this
setting, unlike with unidirectional or symmetric bidirectional controllers,
string stability can be recovered when disturbances act only on a small
(-independent) set of leading vehicles. This improves existing results from
the literature with this assumption. We also indicate that string stability
with respect to arbitrarily distributed disturbances cannot be achieved with
this controller.Comment: Version 2 corrects a typo in the proof, and adds the proof of
stability before string stability. Slightly longer than published versio
Sensitivity Function Trade-offs for Networks with a String Topology
We present two sensitivity function trade-offs that apply to a class of
networks with a string topology. In particular we show that a lower bound on
the H-infinity norm and a Bode sensitivity relation hold for an entire family
of sensitivity functions associated with growing the network. The trade-offs we
identify are a direct consequence of growing the network, and can be used to
explain why poorly regulated low frequency behaviours emerge in long vehicle
platoons even when using dynamic feedback
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