Title: Fundamental Trade-offs in Robust Control with Heterogeneous
Uncertainty

Speaker: Tamer Basar (University of Illinois at Urbana-Champaign)

Abstract: The paradigm of networked control systems, where the feedback
loop is closed over heterogeneous networks, has opened up a vast number
of opportunities for applications in different fields while creating
also a number of challenges with regard to reliability, robustness, and
security of control operations. This talk will address these
challenges, where networks providing sensor measurements to
controller(s) and those carrying control signals to the plant as well
as the plant itself are vulnerable to stochastic as well as adversarial
disturbances and sporadic failure of channel connectivity. The question
of interest is the extent to which the plant, measured in terms of a
performance metric, can tolerate such disturbances and failures, which
themselves are also quantified in terms of some appropriate metrics.

Following a general overview of networked control problems, the talk
will focus on linear-quadratic systems, with norm-bounded deterministic
(adversarial) disturbance inputs and hybrid stochastic uncertainty,
both of which impact network channels, where the latter is
characterized by additive Gaussian noise and Bernoulli type failures.
Explicit results for both the estimation problem and the control
problem will be discussed under the TCP (Transmission Control Protocol)
type information structure (which leads to certainty-equivalance, but
not to separation of estimation and control), and the trade-offs
between control performance, disturbance energy, and channel failure
rates (that is, channel reliability) will be quantified. Under the UDP
(User Datagram Protocol) type packet loss acknowledgment process, on
the other hand, there is no certainty- equivalance, but still some
trade-off results can be obtained. The talk will conclude with a
discussion of future directions of research in this topical area and
the challenges that lie ahead.