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Robust Sensor Selection Strong Detectability

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posted on 2019-01-16, 15:59 authored by Nathaniel T. WoodfordNathaniel T. Woodford
An unknown input observer provides perfect asymptotic tracking of the state of a system affected by unknown inputs. Such an observer exists (possibly requiring a delay in estimation) if and only if the system satisfies a property known as strong detectability. In this thesis, we consider the problem of selecting (at design-time) a minimum cost subset of sensors from a given set to make a given system strongly detectable. We show this problem is NP-hard even when the system is stable. Furthermore, we show it is not possible to approximate the minimum cost within a factor of log(n) in polynomial-time (unless P=NP). However, we prove if a given system (with a selected set of sensors) is already strongly detectable, finding the smallest set of additional sensors to install to obtain a zero-delay observer can be done in polynomial time. Next we consider the problem of attacking a set of deployed sensors to remove the property of strong detectability. We show finding the smallest number of sensors to remove is NP-hard. Lastly through simulations, we analyze two greedy approaches for approximating the strong detectability sensor selection problem.


Degree Type

Master of Science in Electrical and Computer Engineering


Electrical and Computer Engineering

Campus location

West Lafayette

Advisor/Supervisor/Committee Chair

Shreyas Sundaram

Additional Committee Member 2

Stanislaw Zak

Additional Committee Member 3

Shaoshuai Mou